Download INDUSTRIAL AND POWER ELECTRONICS E

NEHRU ARTS AND SCIENCE COLLEGE
DEPARTMENT OF ELECTRONICS AND COMMUNICATION
E- LEARNING MATERIAL
SUBJECT: INDUSTRIAL AND POWER ELECTRONICS
STAFF NAME: S. VENKATESAN
INDUSTRIAL AND POWER ELECTRONICS
UNIT I
Principles of single phase inverter, converter, cyclo converter and DC chopper –
UPS – HVDC –static circuit breaker – over voltage protection – battery charging
circuit – SCR current limiting circuit breaker – static AC and DC switches –
flasher circuits - time delay circuits – fan regulatorusing TRIAC – thyristor
protection circuits: over current protection – over voltage protection –
SECTION A
1) Explain INVERTER?
An inverter is an electrical device that converts direct current (DC) to
alternating current (AC); the converted AC can be at any required voltage and
frequency with the use of appropriate transformers, switching, and control circuits.
2) what are the power problem involve in UPS?
Spikes, defined as a brief high voltage excursion.
Noise, defined as a high frequency transient or oscillation, usually injected into
the line by nearby equipment.
Frequency instability: defined as temporary changes in the mains frequency.
Harmonic distortion: defined as a departure from the ideal sinusoidal
waveform expected on the line
3) DEFINE POWER ELECTRONICS?
Power electronic converters can be found wherever there is a need to modify a
form of electrical energy (i.e. change its voltage, current or frequency). The power
range of these converters is from some milliwatts (as in a mobile phone) to
hundreds of megawatts (e.g. in a HVDC transmission system). With "classical"
electronics, electrical currents and voltage are used to carry information, whereas
with power electronics, they carry power. Thus, the main metric of power
electronics becomes the efficiency.
4) Explain classifications of power conversion system?
The power conversion systems can be classified according to the type of the input
and output power



AC to DC (rectifier)
DC to AC (inverter)
DC to DC (DC to DC converter)
5) In dc choppers, per unit ripple voltage is maximum when duty cycle is
___________
 0.5
6) A cycloconverter is a ____________
 Frequency changer
7) Inverter is a circuit which ____________
 Convert dc power to ac
8) Waveform of output voltage of a single phase bridge inverter--------------- Square wave
9) A typical single phase bridge inverter uses __________ and __________
 Four thyristers and four diodes
SECTION B
1) WHAT IS CYCLOCONVERTER?
A cycloconverter or a cycloinverter converts an AC waveform, such as the mains supply,
to another AC waveform of a lower frequency, synthesizing the output waveform from segments
of the AC supply without an intermediate direct-current link
2) WHAT IS DC CHOPPER?
The DC chopper converts directly from DC to DC and is a relatively latest technology
with good efficiency. It may be visualized as a DC equivalent to an AC transformer, because, in
performing DC-to-DC conversion, its behavior is similar to that of a continuously variable turnratio transformer.
3) WHAT IS UPS?
An Uninterruptible power supply (UPS), also known as a battery backup, provides
emergency power and, depending on the topology, line regulation as well to connected
equipment by supplying power from a separate source when utility power is not available.
4) DEFINE HVDC?
A high-voltage, direct current (HVDC) electric power transmission system uses direct
current for the bulk transmission of electrical power, in contrast with the more common
alternating current systems
5) DEFINE TIME DELAY CIRCUITS?
In the design of analog circuits, there are times when you would need to delay a pulse that came
into a circuit before being used for the next process. This time delay circuit uses a 555 timer to
delay a pulse that comes in to a maximum time of 75 seconds.
SECTION C
1) EXPLAIN ABOUT CYCLOCONVERTER?
A cycloconverter or a cycloinverter converts an AC waveform, such as the mains supply,
to another AC waveform of a lower frequency, synthesizing the output waveform from segments
of the AC supply without an intermediate direct-current link (Dorf 1993, pp. 2241–2243 and
Lander 1993, p. 181). They are most commonly used in three phase applications. In most power
systems, the amplitude and the frequency of input voltage to a cycloconverter tend to be fixed
values, whereas both the amplitude and the frequency of output voltage of a cycloconverter tend
to be variable. The output frequency of a three-phase cycloconverter must be less than about onethird to one-half the input frequency (Lander 1993, p. 188). The quality of the output waveform
improves if more switching devices are used (a higher pulse number). Cycloconverter are used in
very large variable frequency drives, with ratings of several megawatts.
A typical application of a cycloconverter is for use in controlling the speed of an AC
traction motor and starting of synchronous motor. Most of these cycloconverter have a high
power output – in the order a few megawatts – and silicon-controlled rectifiers (SCRs) are used
in these circuits. By contrast, low cost, low-power cycloconverter for low-power AC motors are
also in use, and many such circuits tend to use TRIACs in place of SCRs. Unlike an SCR which
conducts in only one direction, a TRIAC is capable of conducting in either direction, but it is
also a three terminal device. It may be noted that the use of a cycloconverter is not as common as
that of an inverter and a cycloinverter is rarely used. However, it is common in very high power
applications[1] such as for ball mills in ore processing and for cement kilns.
The switching of the AC waveform creates noise, or harmonics, in the system that
depends mostly on the frequency of the input waveform. These harmonics can damage sensitive
electronic equipment. If the relative difference between the input and output waveforms are
small, then the converter can produce sub harmonics. Sub harmonic noise occurs at a frequency
below the output frequency, and cannot be filtered by load inductance. This limits the output
frequency relative to the input. These limitations make cycloconverter often inferior to a DC link
converter system for most applications.
2) EXPLAIN ABOUT DC CHOPPER?
The DC chopper converts directly from DC to DC and is a relatively latest technology
with good efficiency. It may be visualized as a DC equivalent to an AC transformer, because, in
performing DC-to-DC conversion, its behavior is similar to that of a continuously variable turnratio transformer.
The chopper can replace the resistor commonly used in series with the armature of DC
motors for speed control. Therefore, it can be used in battery operated vehicles and applications
where energy saving is a prime consideration. Choppers used in subway cars also reduce tunnel
heating. Choppers can also provide regenerative braking of the motor and return the energy back
to the supply. This results in energy saving for transportation systems with frequent stops.
Choppers therefore find wide application in transaction system all over the world. Choppers are
successfully used in BART (Bay Area Rapid Transit) system in San Francisco and in subway
cars in Toronto and Montreal. Choppers are also used in other applications such as interurban
and trolley cars, marine hoists, forklifts trucks and mine-haulers.
Choppers are most likely to be used in future electric vehicles for speed control as well as
braking. Nowadays, these also find lots of applications in continuous process plants like glass,
fertilizer and tire manufacturing industries. A few good features of the chopper drives are:
smooth control, high efficiency, fast response and regeneration.
Principles of Chopper Operation
A chopper is a solid-state On/Off switch, which connects load to and disconnects it from
the supply and produces a chopped load voltage from a constant-input supply voltage. During the
period t-On. When the s Principles of Chopper Operation
A chopper is a solid-state On/Off switch, which connects load to and disconnects it from
the supply and produces a chopped load voltage from a constant-input supply voltage. During the
period t-On. When the switch is on, the supply terminals are connected to the load terminals.
During the interval t-Off, when the switch is Off, load current flows through free-wheeling diode
Dfw and the load terminals are shorted. A chopped DC voltage is thus produced at the load
terminals. Which is on, the supply terminals are connected to the load terminals. During the
interval t-Off, when the switch is Off, load current flows through free-wheeling diode Dfw and
the load terminals are shorted. A chopped DC voltage is thus produced at the load terminals.
3) EXPLAIN UPS?
An Uninterruptible power supply (UPS), also known as a battery backup, provides emergency
power and, depending on the topology, line regulation as well to connected equipment by
supplying power from a separate source when utility power is not available. It differs from an
auxiliary or emergency power system or standby generator, which does not provide instant
protection from a momentary power interruption. A UPS, however, can be used to provide
uninterrupted power to equipment, typically for 5–15 minutes until an auxiliary power supply
can be turned on, utility power restored, or equipment safely shut down.
While not limited to safeguarding any particular type of equipment, a UPS is typically
used to protect computers, data centers, telecommunication equipment or other electrical
equipment where an unexpected power disruption could cause injuries, fatalities, serious
business disruption or data loss. UPS units range in size from units to back up single computers
without monitor (around 200 VA) to units powering entire data centers, buildings, or even
cities[1] (several megawatts).
UPS units are used to correct various common power problems:

Power failure

Voltage surge

Voltage spike

Under-voltage (brownout)

Over-voltage

Line noise

Frequency variation

Switching transient

Harmonic distortion
UPS units are divided into categories based on which of the above problems they address,
and some manufacturers categorize their products in accordance with the number of power
related problems they address.
4) EXPLAIN HVDC?
A high-voltage, direct current (HVDC) electric power transmission system uses direct current
for the bulk transmission of electrical power, in contrast with the more common alternating
current systems. For long-distance distribution, HVDC systems are less expensive and suffer
lower electrical losses. For shorter distances, the higher cost of DC conversion equipment
compared to an AC system may be warranted where other benefits of direct current links are
useful.
High voltage transmission
High voltage is used for transmission to reduce the energy lost in the resistance of the
wires. For a given quantity of power transmitted, higher voltage reduces the transmission power
loss. Power in a circuit is proportional to the current, but the power lost as heat in the wires is
proportional to the square of the current. However, power is also proportional to voltage, so for a
given power level, higher voltage can be traded off for lower current. Thus, the higher the
voltage, the lower the power loss. Power loss can also be reduced by reducing resistance,
commonly achieved by increasing the diameter of the conductor; but larger conductors are
heavier and more expensive.
High voltages cannot be easily used in lighting and motors, and so transmission-level
voltage must be reduced to values compatible with end-use equipment. The transformer, which
only works with alternating current, is an efficient way to change voltages. The competition
between the DC of Thomas Edison and the AC of Nikola Tesla and George Westinghouse was
known as the War of Currents, with AC emerging victorious. Practical manipulation of DC
voltages only became possible with the development of high power electronic devices such as
mercury arc valves and later semiconductor devices, such as thyristors, insulated-gate bipolar
transistors (IGBTs), high power capable MOSFETs (power metal–oxide–semiconductor fieldeffect transistors) and gate turn-off thyristors (GTOs).
Advantages of HVDC over AC transmission
The advantage of HVDC is the ability to transmit large amounts of power over long
distances with lower capital costs and with lower losses than AC. Depending on voltage level
and construction details, losses are quoted as about 3% per 1,000 km.[citation needed] Highvoltage direct current transmission allows efficient use of energy sources remote from load
centers.
Disadvantages
The disadvantages of HVDC are in conversion, switching, control, availability and maintenance
2) Explain over voltage protection?
Voltage spike.
When the voltage in a circuit or part of it is raised above its upper design limit, this is known as
overvoltage. The conditions may be hazardous. Depending on its duration, the overvoltage event
can be transient—a voltage spike—or permanent, leading to a power surge.
Explanation
Lack of 3-phase electric system connected by star. If zero breakes off, small-power appliances will be
destroyed by overvoltage
Electronic and electrical devices are designed to operate at a certain maximum supply voltage,
and considerable damage can be caused by voltage that is higher than that for which the devices
are rated.
For example an electric light bulb has a wire in it that at the given rated voltage will carry a
current just large enough for the wire to get very hot (giving off light and heat), but not hot
enough for it to melt. The amount of current in a circuit depends on the voltage supplied: if the
voltage is too high, then the wire may melt and the light bulb would have "burned out". Similarly
other electrical devices may stop working, or may even burst into flames if an overvoltage is
delivered to the circuit of which these devices are part.
Sources
Natural
A typical natural source of transient overvoltage events is lightning. Bursts of solar wind
following solar flares are also known to cause overvoltage in electrical circuits, especially
onboard space satellites.
Man made
Man-made sources of spikes are usually caused by electromagnetic induction when
switching on or off inductive loads (such as electric motors or electromagnets), or by switching
heavy resistive AC loads when zero-crossing circuitry is not used - anywhere a large change of
current takes place. One of the purposes of electromagnetic compatibility compliance is to
eliminate such sources.
An important potential source of dangerous overvoltage is electronic warfare. There is
intensive military research in this field, whose goal is to produce various transient
electromagnetic devices designed to generate electromagnetic pulses that will disable an enemy's
electronic equipment. A recent military development is that of the exploding capacitor designed
to radiate a high voltage electromagnetic pulse. Another intense source of an electromagnetic
pulse is a nuclear explosion.
Conduction path
The transient pulses can get into the equipment either by power or data lines, or directly
through space from a strong electromagnetic field change - an electromagnetic pulse (EMP).
Filters are used to prevent spikes entering or leaving the equipment through wires, and the
devices coupled electromagnetically to space (such as radio-frequency pick-up coils in MRI
scanners) are protected by shielding
UNIT II
WELDING AND HEATING
Welding and Heating: resistance welding – types of resistance welding – electronic control
inresistance welding: ignitron contractor – heat control – non synchronous timer –
synchronousweld timer – sequence timer – energy storage welding systems – induction heating –
applicationsof induction heating – high frequency power source for induction heating – dielectric
heating –application of dielectric heating.
SECTION A
1)Explain welding?
Welding is a fabrication or sculptural process that joins materials, usually metals or
thermoplastics, by causing coalescence. This is often done by melting the workpieces and
adding a filler material to form a pool of molten material (the weld pool) that cools to become a
strong joint, with pressure sometimes used in conjunction with heat, or by itself, to produce the
weld. This is in contrast with soldering and brazing, which involve melting a lower-melting-point
material between the workpieces to form a bond between them, without melting the
workpieces.
2)List out some energy sources of welding?
Many different energy sources can be used for welding, including a gas flame, an electric arc, a
laser, an electron beam, friction, and ultrasound.
3) ERW processes ____________
 High ac current at low voltage
4) In ERW electrodes are ____________
 Cooled by circulated water
5) Dielectric losses in a dielectric material are _________
 Vary linearly with f
6) For welding aluminum alloy the method used is __________
 Tungsten arc welding
7) In seam welding the flow current through the electrode should be
 Intermittent
SECTIONB
1) DEFINE ERW?
Electric resistance welding (ERW) refers to a group of welding processes such as spot and seam
welding that produce coalescence of faying surfaces where heat to form the weld is generated by
the resistance of the welding current through the workpieces
2)WHAT IS INDUCTION HEATING?
Induction heating is the process of heating an electrically conducting object (usually a metal) by
electromagnetic induction, where eddy currents are generated within the metal and resistance
leads to Joule heating of the metal
3)Define Dielectric heating?
Dielectric heating, also known as electronic heating, RF heating, high-frequency
heating and diathermy, is the process in which radio wave or microwave electromagnetic
radiation heats a dielectric material. This heating is caused by dipole rotation.
SECTION C
1) EXPLAIN ERW?
Electric resistance welding (ERW) refers to a group of welding processes such as spot and
seam welding that produce coalescence of faying surfaces where heat to form the weld is
generated by the resistance of the welding current through the work pieces. Some factors
influencing heat or welding temperatures are the proportions of the work pieces, the electrode
materials, electrode geometry, electrode pressing force, weld current and weld time. Small pools
of molten metal are formed at the point of most electrical resistance (the connecting surfaces) as
a high current (100–100,000 A) is passed through the metal. In general, resistance welding
methods are efficient and cause little pollution, but their applications are limited to relatively thin
materials and the equipment cost can be high.
Spot welding
Spot welding is a resistance welding method used to join two to four overlapping metal
sheets which are up to 3 mm thick each. In some applications with only two overlapping metal
sheets, the sheet thickness can be up to 6 mm. Two copper electrodes are simultaneously used to
clamp the metal sheets together and to pass current through the sheets. When the current is
passed through the electrodes to the sheets, heat is generated due to the higher electrical
resistance where the surfaces contact each other. As the heat dissipates into the work, the rising
temperature causes a rising resistance, and the heat is then generated by the current through this
resistance. The surface resistance lowers quickly, and the heat is soon generated only by the
materials' resistance. The water cooled copper electrodes remove the surface heat quickly, since
copper is an excellent conductor. The heat in the center has nowhere to go, as the metal of the
workpiece is a poor conductor of heat by comparison. The heat remains in the center, melting the
metal from the center outward. As the heat dissipates throughout the workpiece in less than a
second the molten, or at least plastic, state grows to meet the welding tips.
There are three basic types of resistance welding bonds: solid state, fusion, and reflow
braze. In a solid state bond, also called a thermo-compression bond, dissimilar materials with
dissimilar grain structure, e.g. molybdenum to tungsten, are joined using a very short heating
time, high weld energy, and high force. There is little melting and minimum grain growth, but a
definite bond and grain interface. Thus the materials actually bond while still in the “solid state”.
The bonded materials typically exhibit excellent shear and tensile strength, but poor peel
strength. In a fusion bond, either similar or dissimilar materials with similar grain structures are
heated to the melting point (liquid state) of both. The subsequent cooling and combination of the
materials forms a “nugget” alloy of the two materials with larger grain growth. Typically, high
weld energies at either short or long weld times, depending on physical characteristics, are used
to produce fusion bonds. The bonded materials usually exhibit excellent tensile, peel and shear
strengths. In a reflow braze bond, a resistance heating of a low temperature brazing material,
such as gold or solder, is used to join either dissimilar materials or widely varied thick/thin
material combinations. The brazing material must “wet” to each part and possess a lower melting
point than the two workpieces. The resultant bond has definite interfaces with minimum grain
growth. Typically the process requires a longer (2 to 100 ms) heating time at low weld energy.
The resultant bond exhibits excellent tensile strength, but poor peel and shear strength.
Seam welding
Like spot welding, seam welding relies on two electrodes to apply pressure and current to
join metal sheets. However, instead of pointed electrodes, wheel- shaped electrodes roll along
and often feed the workpiece, making it possible to make long continuous welds. In the past, this
process was used in the manufacture of beverage cans, but now its uses are more limited.
Seam welding is the act of welding two similar metals together at a seam, usually on a
piece of automated equipment. This process differs from butt welding, as that is generally a
process that is done on static (non-moving) metals.
Seam welding consists of two (or more) moving metals through forming production
equipment. A common use of seam welding is for copper and steel piping for construction.
Varying the amperage as well as speeds of the moving metals ensure a proper seam weld, and
many industries use this process for creation of finished goods.
Resistance seam welding is a resistance welding process that produces a weld at the
faying surfaces of overlapped parts along a length of a joint. The weld may be made by
overlapping weld nuggets, a continuous weld nugget or by forging the joint as it is heated to the
welding temperature by resistance to the flow of welding current. Instead of using two
cylindrical electrodes as in case of spot welding, here two circular disks are used as electrodes.
The work piece is passed through the space between the two discs, and under pressure applied by
the discs and current flowing through them, a continuous weld is formed.
With seam welding the material passes between two rotating wheels or welding rollers. The
welding rollers perform three tasks:

Weld current transmission

Welding pressure

Feed motion transmission
The high electrical A/C current (low voltage) is supplied from a transformer.
The overlap of the work piece with its comparatively high electrical resistance is intensely
heated by the current. With each positive or negative current half-wave the parts are heated to a
semi-molten condition, especially at the current peaks. The semi-molten overlap surfaces are
pressed together by the welding pressure which causes them to bond together into a uniforming
welded structure after cooling. Most seam welded technologies use water cooling through the
weld roller assemblies due to the intense heat generated.
Seam welding is mainly used on the seams of tubes and pipes for its ease and accuracy.
The resulting weld from the welding wheels is extremely durable due to the length of the contact
area.
Ultrasonic seam welders use energy at a frequency around 20 kHz to vibrate the material
being worked on. The vibration creates friction, the friction creates heat, causing the material to
melt together. Ultrasonic welding is the process used to create the plastic packages that are
extremely hard to open without destroying the package.
Other methods
Other ERW methods include flash welding, resistance projection welding, and upset welding.
2) EXPLAIN ABOUT INDUCTION HEATING?
Induction heating is the process of heating an electrically conducting object (usually a
metal) by electromagnetic induction, where eddy currents are generated within the metal and
resistance leads to Joule heating of the metal. An induction heater (for any process) consists of
an electromagnet, through which a high-frequency alternating current (AC) is passed. Heat may
also be generated by magnetic hysteresis losses in materials that have significant relative
permeability. The frequency of AC used depends on the object size, material type, coupling
(between the work coil and the object to be heated) and the penetration depth
Induction furnace
An induction furnace uses induction to heat metal to its melting point. Once molten, the
high-frequency magnetic field can also be used to stir the hot metal, which is useful in ensuring
that alloying additions are fully mixed into the melt. Most induction furnaces consist of a tube of
water-cooled copper rings surrounding a container of refractory material. Induction furnaces are
used in most modern foundries as a cleaner method of melting metals than a reverberatory
furnace or a cupola. Sizes range from a kilogram of capacity to a hundred tonnes capacity.
Induction furnaces often emit a high-pitched whine or hum when they are running, depending on
their operating frequency.
Metals melted include iron and steel, copper, aluminium, and precious metals. Because it
is a clean and non-contact process it can be used in a vacuum or inert atmosphere. Vacuum
furnaces make use of induction heating for the production of specialty steels and other alloys that
would oxidize if heated in the presence of air.
Induction welding
A similar, smaller-scale process is used for induction welding. Plastics may also be
welded by induction, if they are either doped with ferromagnetic ceramics (where magnetic
hysteresis of the particles provides the heat required) or by metallic particles.
Induction tube welding
Induction heating is used in the manufacture of seam welded tube. Currents induced in a
tube run along the open seam and heat the edges resulting in a temperature high enough for
welding. At this point the seam edges are forced together and the seam is welded. The RF current
can also be conveyed to the tube by brushes, but the result is still the same - the current flows
along the open seam, heating it.
Induction cooking
In induction cooking, an induction coil in the cook-top heats the iron base of cookware.
Copper bottomed pans, aluminium pans and most stainless steel pans are generally unsuitable.
The heat induced in the base is transferred to the food via conduction. Benefits of
induction cookers include efficiency, safety (the induction cook-top is not heated itself) and
speed. Drawbacks include the fact that non-metallic cookware such as glass and ceramic cannot
be used on an induction cook-top. Both installed and portable induction cookers are available.
Induction brazing
Induction brazing is often used in higher production runs. It produces uniform results and is
very repeatable.
Induction sealing
Induction heating is often used in induction sealing or "cap sealing".
Heating to fit
Induction heating is often used to heat an item causing it to expand prior to fitting or
assembly. Bearings are routinely heated in this way using mains frequency (50/60Hz) and a
laminated steel transformer type core passing through the centre of the bearing.
Heat treatment
Induction heating is often used in the heat treatment of metal items. The most common
applications are induction hardening of steel parts and induction soldering/brazing as a means of
joining metal components. Induction heating can produce high power densities which allow short
interaction times to reach the required temperature. This gives tight control of the heating
'pattern' with the pattern following the applied magnetic field quite closely and allows reduced
thermal distortion and damage.
This ability can be used in hardening to produce parts with varying properties. The most
common hardening process is to produce a localized surface hardening of an area that needs
wear-resistance, while retaining the toughness of the original structure as needed elsewhere. The
depth of induction hardened patterns can be controlled through choice of induction-frequency,
power-density and interaction time.
There are limits to the flexibility of the process - mainly arising from the need to produce
dedicated inductors for many applications. This is quite expensive and requires the marshalling
of high current-densities in small copper inductors, which can require specialized engineering
and 'copper-fitting'.
UNIT III
Generation of ultrasonic waves – applications of ultrasonic – production of X rays
–applications – Measurement of non electrical quantities: pressure measurements –
displacementmeasurements – level measurements – flow measurements –
measurement of thickness.
SECTION A
1) Write a short on X-RAY?
X-radiation (composed of X-rays) is a form of electromagnetic radiation. X-rays have a
wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the
range 30 petahertz to 30 exahertz (3×1016 Hz to 3×1019 Hz) and energies in the range
120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma
rays. In many languages, X-radiation is called Röntgen radiation.
2) List out some measurements of Non-electrical quantities?
Pressure, Displacement, Level, Flow, Thickness .
3) Ultrasonic waves have frequency ____________
 20 kc/s and above
4) Ultrasonic waves are _________
 Sound waves of frequency greater than 20 kc/s
5) Tuning forks may produce ultrasonic waves of frequencies __________
 Upto about 90 kc/s
SECTION B
1) EXPLAIN ABOUT ULTRASONIC WAVES?
Ultrasonic’s or ultrasound, derived from the Latin words "ultra," meaning beyond, and
"sonic," meaning sound, is a term used to describe sound waves that vibrate more rapidly than
the human ear can detect.
Sound waves travel as concentric hollow spheres. The surfaces of the spheres are
compressed air molecules, and the spaces between the spheres are expansions of the air
molecules through which the sound waves travel. Sound waves are thus a series of compressions
and expansions in the medium surrounding them. Although we are used to thinking of sound
waves as traveling through air, they may also propagate through other media.
The technical name for one expansion and one compression is a cycle. Thus, a vibration
rate of 50 cycles per second produces 50 expansions and 50 compressions each second. The
term frequency designates the number of cycles per unit of time that a sound wave vibrates. One
cycle per second is called a hertz and is abbreviated Hz. Other useful units of scale in
ultrasonic’sare kilohertz (kHz), which represents 1,000 Hz; and megahertz (MHz), representing
1,000,000 Hz or 1,000 kHz.
Most people can only detect frequencies of sound that fall between 16 and 16,000 Hz.
Ultrasonics has come to describe sound waves with frequencies greater than 16,000 Hz, or 16
kHz. Some insects can produce ultrasound with frequencies as high as 40 kHz. Small animals
TABLE 1. VELOCITY OF SOUND IN VARIOUS MEDIA
Material
Velocity (ft/sec)
TABLE 1. VELOCITY OF SOUND IN VARIOUS MEDIA
Material
Velocity (ft/sec)
All measurements at 25°C (room temperature) unless otherwise indicated.
Sea water
5023
Distilled water
4908
Chloroform
3237
Dry air at 0°C
1086
Hydrogen at 0°C
4212
Brick
11,972
Clay rock
11,414
Cork
1640
TABLE 1. VELOCITY OF SOUND IN VARIOUS MEDIA
Material
Velocity (ft/sec)
Paraffin
4264
Tallow
1279
Polystyrene
3018
Fused silica
18,893
Aluminum
16,400
Gold
6658
Silver
8790
Concrete
12,000
Stainless steel
16,400
such as cats and dogs hear frequencies of up to 30 kHz; and bats are known to detect frequencies
of up to 100 kHz.
A sound wave that causes compressions and expansions of the molecules in the medium
surrounding it as it propagates is called a longitudinal wave. The distance from one compression
to the next is known as the wavelength of the sound wave. Sound waves with long wavelengths
pass over small objects in much the same way that ocean waves pass over small objects. Sound
waves with short wavelengths, on the other hand, tend to be diffracted or scattered by objects
comparable to them in size.
The propagation velocity of a sound wave is obtained by multiplying the frequency of
the sound wave by its wavelength. Thus, if the wavelength and frequency of the sound wave in a
given medium are known, its velocity can also be calculated. The sound velocities in a variety of
materials are shown in Table 1.
As ultrasonic waves tend to have very high frequencies, it follows that they also have very short
wavelengths. As a result, ultrasonic waves can be focused in narrow, straight beams.
2) EXPLAIN THE APPLICATIONS OF ULTRASONIC?
Applications
The number of applications for ultrasound seems to be limited only by the human
imagination. There are literally dozens of ways that people have already found to make use of
ultrasound.
Coagulation
Ultrasound has been used to bind, or coagulate, solid or liquid particles that are present in
dust, mist, or smoke into larger clumps. The technique is used in a process called ultrasonic
scrubbing, by which particulate matter is coagulated in smokestacks before it pollutes the
atmosphere. Coagulation has also been used at airports to disperse fog and mist.
Humidification
In ultrasonic humidification, water is reduced to a fine spray by means of ultrasonic
vibrations. The water droplets are propelled into a chamber where they are mixed with air, and a
mist of air and water leaves the humidifier and enters the room to be humidified.
Milk homogenization and pasteurization
Ultrasonic waves can be used to break up fat globules in milk, so that the fat mixes with
the milk (homogenization). In addition, pasteurization, the removal of harmful bacteria and
microorganisms, is sometimes done ultrasonically.
Drilling
By attaching an ultrasonic impact grinder to a magnetostrictive transducer and using an
abrasive liquid, holes of practically any shape can be drilled in hard, brittle materials such as
tungsten carbide or precious stones. The actual cutting or drilling is done by feeding an abrasive
material, frequently silicon carbide or aluminum oxide, to the cutting area.
Soldering
In ultrasonic soldering, high frequency vibrations are used to produce microscopic
bubbles in molten solder. This process removes the metal oxides from the joint or surface to be
soldered, and eliminates the need for flux.
Electronic eavesdropping
Conversations can be overheard without using microphones by directing ultrasonic waves
at the window of the room being monitored. Sounds in the room cause the window to vibrate; the
speech vibrations produce characteristic changes in the ultrasonic waves that are reflected back
into the monitor. A transducer can be used to convert the reflected vibrations to electrical signals
that can be reconstructed as audible sounds.
Radio
Radio talk shows routinely use ultrasonic delay lines to monitor and cut off abusive
callers before their comments are aired during radio talk shows. The ultrasonic delay line
bounces the voice signal back and forth between two transducers until it has been monitored,
then releases it for broadcast.
6) DEFINE PRESSURE MEASSUREMENT?
Many techniques have been developed for the measurement of pressure and vacuum.
Instruments used to measure pressure are called pressure gauges or vacuum gauges.
A manometer could also be referring to a pressure measuring instrument, usually limited to
measuring pressures near to atmospheric. The term manometer is often used to refer specifically
to liquid column hydrostatic instruments.
A vacuum gauge is used to measure the pressure in a vacuum --- which is further divided
into two subcategories: high and low vacuum (and sometimes ultra-high vacuum). The
applicable pressure range of many of the techniques used to measure vacuums have an overlap.
Hence, by combining several different types of gauge, it is possible to measure system pressure
continuously from 10 mbar down to 10-11 mbar
SECTIONC
1) EXPLAIN ABOUT X-RAYS?
X rays are a form of electromagnetic radiation with wavelengths that range from about
10 −7 to about 10 −15 meter. No sharp boundary exists between X rays and ultraviolet radiation
on the longer wavelength side of this range. Similarly, on the shorter wavelength side, X rays
blend into that portion of the electromagnetic spectrum called gamma rays, which have even
shorter wavelengths.
X rays have wavelengths much shorter than visible light. (Wave lengths of visible light
range from about 3.5 × 10 −9 meter to 7.5 × 10 −9 meter.) They also behave quite differently.
They are invisible, are able to penetrate substantial thicknesses of matter, and can ionize matter
(meaning that electrons that normally occur in an atom are stripped away from that atom). Since
their discovery in 1895, X rays have become an extremely important tool in the physical and
biological sciences and the fields of medicine and engineering: Also known as target electrode;
the positively charged electrode in an X-ray tube.
Cathode: The negatively charged electrode in an X-ray tube. An X-ray technique in which a
three-dimensional image of a body part is put together by computer using a series of X-ray
pictures taken from different angles along a straight line.
Electrode: A material that will conduct an electrical current, usually a metal, used to carry
electrons into or out of an electrochemical cell.
Hard X
Destru
X rays with high penetrating power.
cA method of analysis that does not require the destruction of the material being tested.
Soft rays: X rays with low penetrating power.
Sync Electromagnetic radiation from certain kinds of particle accelerators that can range from
the visible region to the X-ray region. A tube from which air has been removed that is used for
the production of X rays.
Product the method by which X rays were produced in Roentgen's first experiments is basically
the one still used today. As shown in the accompanying X-ray tube drawing, an X-ray tube
consists of a glass tube from which air has been removed. The tube contains two electrodes, a
negatively charged electrode called the cathode and a positively charged target called the anode.
The two electrodes are attached to a source of direct (DC) current. When the current is turned on,
electrons are ejected from the cathode. They travel through the glass tube and strike a target. The
energy released when the electrons hit the target is emitted in the form of X rays.
The wavelength of the X rays produced is determined by the metal used for the target and
the energy of the electrons released from the cathode. X rays with higher frequencies and,
therefore, higher penetrating power are known as hard X rays. Those with lower frequencies and
lower penetrating power are known as soft X rays.
Applications of rays The earliest uses of X rays were based on the discoveries made
by Roentgen, namely their ability to distinguish bone and teeth from flesh in X-ray
photographs. When an X-ray beam is focused on a person's hand or jaw, for example, the
beam passes through flesh rather easily but is absorbed by bones or teeth. The picture
produced in this case consists of light areas that represent bone and teeth and dark areas
that represent flesh. Some applications of this principle in medicine are the diagnosis of
broken bones and torn ligaments, the detection of breast cancer in women, or the discovery
of cavities and impacted wisdom teeth.
X rays can be produced with energies sufficient to ionize the atoms that make up human
tissue. Thus, X rays can be used to kill cells. This is just what is done in some types of cancer
therapy. X-radiation is directed against cancer cells in the hope of destroying them while doing
minimal damage to nearby normal cells. Unfortunately, too much exposure of normal cells to X
rays can cause the development of cancer. For this reason, great care is taken by physicians and
dentists when taking X rays of any type to be sure that the exposure to the rest of the patient's
body is kept at an absolute minimum.
A relatively new technique for using X rays in the field of medicine is called
computerized axial tomography, producing what are called CAT scans. A CAT scan produces a
cross-sectional picture of a part of the body that is much sharper than a normal X ray. Normal X
rays are taken through the body, producing a picture that may show organs and body parts superimposed
Figure 1. An X-ray tube. (Reproduced by permission of
Robert L. Wolke on one another. In contrast, in making a CAT scan, a narrow beam of X rays is
sent through the region of interest from many different angles. A computer is then used to
reconstruct the cross-sectional picture of that region.
Nondestr The term nondestructive testing refers to methods that can be used to study the
structure of a material without destroying the material itself. For example, one could find out
what elements are present in a piece of metal alloy by dissolving the alloy in acid and conducting
chemical tests. But this process of testing obviously destroys the alloy being tested.
X rays can be used to study the structure of a material without actually destroying it. One
approach is based on the usual method of producing X rays. A sample of unknown material is
used as the target in an X-ray machine and bombarded with high energy electrons. The X-ray
pattern produced by the sample can be compared with the X-ray patterns for all known elements.
Based on this comparison, the elements present in the unknown sample can be identified. A
typical application of this technique is the analysis of hair or blood samples or some other
material being used as evidence in a criminal investigation.
X rays are used for nondestructive testing in business and industry in many other ways.
For example, X-ray pictures of whole engines or engine parts can be taken to look for defects
without having to take an engine apart. Similarly, sections of oil and natural gas pipelines can be
examined for cracks or defective welds. Airlines also use X-ray detectors to check the baggage
of passengers for guns or other illegal objects.
SynchroIn recent years an interesting new source of X rays has been developed called
synchrotron radiation. Synchrotron radiation is often produced by particle accelerators (atomsmashers). A particle accelerator is a machine used to accelerate charged particles, such as
electrons and protons, to very high speeds. As these particles travel in a circle around a particle
accelerator, they may give off energy in the form of X rays. These X rays are what make up
synchrotron radiation.
One of the more important commercial applications of synchrotron radiation is in the
field of X-ray lithography. X-ray lithography is a technique used in the electronics industry for
the manufacture of high density integrated circuits. (A circuit is a complete path of electric
current, including the source of electric energy.) The size of the circuit elements is limited by the
wavelength of the light used in them. The shorter the wavelength the smaller the circuit
elements. If X rays are used instead of light, the circuits can be made much smaller, thereby
permitting the manufacture of smaller electronic devices such as computers.
2) EXPLAIN ABOUT PRESSURE MESSUREMENT
Pressure measurement
The construction of a bourdon tube gauge, construction elements are made of brass
Many techniques have been developed for the measurement of pressure and vacuum. Instruments
used to measure pressure are called pressure gauges or vacuum gauges.
A manometer could also be referring to a pressure measuring instrument, usually limited
to measuring pressures near to atmospheric. The term manometer is often used to refer
specifically to liquid column hydrostatic instruments.
A vacuum gauge is used to measure the pressure in a vacuum --- which is further divided
into two subcategories: high and low vacuum (and sometimes ultra-high vacuum). The
applicable pressure range of many of the techniques used to measure vacuums have an overlap.
Hence, by combining several different types of gauge, it is possible to measure system pressure
continuously from 10 mbar down to 10-eference
Although pressure is an absolute quantity, everyday pressure measurements, such as for
tire pressure, are usually made relative to ambient air pressure.
In other cases measurements are made relative to a vacuum or to some other ad hoc reference.
When distinguishing between these zero references, the following terms are used:

Absolute pressure is zero referenced against a perfect vacuum, so it is equal to gauge
pressure plus atmospheric pressure.

Gauge pressure is zero referenced against ambient air pressure, so it is equal to absolute
pressure minus atmospheric pressure. Negative signs are usually omitted.

Differential pressure is the difference in pressure between two points.
The zero reference in use is usually implied by context, and these words are only added when
clarification is needed. Tire pressure and blood pressure are gauge pressures by convention,
while atmospheric pressures, deep vacuum pressures, and altimeter pressures must be absolute.
Differential pressures are commonly used in industrial process systems. Differential pressure
gauges have two inlet ports, each connected to one of the volumes whose pressure is to be
monitored. In effect, such a gauge performs the mathematical operation of subtraction through
mechanical means, obviating the need for an operator or control system to watch two separate
gauges and determine the difference in readings. Moderate vacuum pressures are often
ambiguous, as they may represent absolute pressure or gauge pressure without a negative sign.
Thus a vacuum of 26 inHg gauge is equivalent to an absolute pressure of 30 inHg (typical
atmospheric pressure) − 26 inHg = 4 inHg.
Atmospheric pressure is typically about 100 kPa at sea level, but is variable with altitude and
weather. If the absolute pressure of a fluid stays constant, the gauge pressure of the same fluid
will vary as atmospheric pressure changes. For example, when a car drives up a mountain, the
tire pressure goes up. Some standard values of atmospheric pressure such as 101.325 kPa or 100
kPa have been defined, and some instruments use one of these standard values as a constant zero
reference instead of the actual variable ambient air pressure. This impairs the accuracy of these
instruments, especially when used at high altitudes.
Use of the atmosphere as reference is usually signified by a (g) after the pressure unit e.g. 30
psi g, which means that the pressure measured is the total pressure minus atmospheric pressure.
There are two types of gauge reference pressure: vented gauge (vg) and sealed gauge (sg).
A vented gauge pressure transmitter for example allows the outside air pressure to be
exposed to the negative side of the pressure sensing diaphragm, via a vented cable or a hole on
the side of the device, so that it always measures the pressure referred to ambient barometric
pressure. Thus a vented gauge reference pressure sensor should always read zero pressure when
the process pressure connection is held open to the air.
A sealed gauge reference is very similar except that atmospheric pressure is sealed on the
negative side of the diaphragm. This is usually adopted on high pressure ranges such as
hydraulics where atmospheric pressure changes will have a negligible effect on the accuracy of
the reading, so venting is not necessary. This also allows some manufacturers to provide
secondary pressure containment as an extra precaution for pressure equipment safety if the burst
pressure of the primary pressure sensing diaphragm is exceeded.
There is another way of creating a sealed gauge reference and this is to seal a high vacuum
on the reverse side of the sensing diaphragm. Then the output signal is offset so the pressure
sensor reads close to zero when measuring atmospheric pressure.
A sealed gauge reference pressure transducer will never read exactly zero because
atmospheric pressure is always changing and the reference in this case is fixed at 1 bar.
An absolute pressure measurement is one that is referred to absolute vacuum. The best
example of an absolute referenced pressure is atmospheric or barometric pressure.
To produce an absolute pressure sensor the manufacturer will seal a high vacuum behind the
sensing diaphragm. If the process pressure connection of an absolute pressure transmitter is open
to the air, it will read the actual barometric pressure.Units
Pressure Units
pound-force
technical
per
pascal
bar
atmosphere
atmosphere
torr
(Pa)
(bar)
(at)
(atm)
(Torr)
1 Pa
≡ 1 N/m2
10−5
1.0197×10−5 9.8692×10−6 7.5006×10−3 145.04×10−6
1 bar
100,000
≡ 106 dyn/cm2 1.0197
1 at
98,066.5
0.980665
1 atm
101,325
1 torr
133.322
1 psi
6.894×103 68.948×10−3
square inch
(psi)
0.98692
750.06
14.5037744
≡ 1 kgf/cm2
0.96784
735.56
14.223
1.01325
1.0332
≡ 1 atm
760
14.696
1.3332×10−3
1.3595×10−3 1.3158×10−3
≡
1
Torr;
≈ 1 mmHg
70.307×10−3 68.046×10−3 51.715
19.337×10−3
≡ 1 lbf/in2
Example reading: 1 Pa = 1 N/m2 = 10−5 bar = 10.197×10−6 at = 9.8692×10−6 atm, etc.
The SI unit for pressure is the pascal (Pa), equal to one newton per square metre (N·m-2
or kg·m-1·s-2). This special name for the unit was added in 1971; before that, pressure in SI was
expressed in units such as N/m². When indicated, the zero reference is stated in parenthesis
following the unit, for example 101 kPa (abs). The pound per square inch (psi) is still in
widespread use in the US and Canada, notably for cars.
A letter is often appended to the psi unit to indicate the measurement's zero reference;
psia for absolute, psig for gauge, psid for differential, although this practice is discouraged by the
NIST [1].
Because pressure was once commonly measured by its ability to displace a column of
liquid in a manometer, pressures are often expressed as a depth of a particular fluid (e.g. inches
of water). The most common choices are mercury (Hg) and water; water is nontoxic and readily
available, while mercury's density allows for a shorter column (and so a smaller manometer) to
measure a given pressure.
Fluid density and local gravity can vary from one reading to another depending on local
factors, so the height of a fluid column does not define pressure precisely. When 'millimetres of
mercury' or 'inches of mercury' are quoted today, these units are not based on a physical column
of mercury; rather, they have been given precise definitions that can be expressed in terms of SI
units. The water-based units usually assume one of the older definitions of the kilogram as the
weight of a litre of water.
Although no longer favoured by measurement experts, these manometric units are still
encountered in many fields. Blood pressure is measured in millimetres of mercury in most of the
world, and lung pressures in centimeters of water are still common.
Natural gas pipeline pressures are measured in inches of water, expressed as '"WC'
('Water Column'). Scuba divers often use a manometric rule of thumb: the pressure exerted by
ten metres depth of water is approximately equal to one atmosphere. In vacuum systems, the
units torr, micrometre of mercury (micron), and inch of mercury (inHg) are most commonly
used. Torr and micron usually indicates an absolute pressure, while inHg usually indicates a
gauge pressure.
Atmospheric pressures are usually stated using kilopascal (kPa), or atmospheres (atm),
except in American meteorology where the hectopascal (hPa) and millibar (mbar) are preferred.
In American and Canadian engineering, stress is often measured in kip. Note that stress is not a
true pressure since it is not scalar. In the cgs system the unit of pressure was the barye (ba), equal
to 1 dyn·cm-2. In the mts system, the unit of pressure was the pieze, equal to 1 sthene per square
metre.
Many other hybrid units are used such as mmHg/cm² or grams-force/cm² (sometimes as
kg/cm² and g/mol2 without properly identifying the force units). Using the names kilogram,
gram, kilogram-force, or gram-force (or their symbols) as a unit of force is forbidden in SI; the
unit of force in SI is the newton (N).
Static and Dynamic pressure:
Static pressure is uniform in all directions, so pressure measurements are independent of
direction in an immobile (static) fluid. Flow, however, applies additional pressure on surfaces
perpendicular to the flow direction, while having little impact on surfaces parallel to the flow
direction. This directional component of pressure in a moving (dynamic) fluid is called dynamic
pressure. An instrument facing the flow direction measures the sum of the static and dynamic
pressures; this measurement is called the total pressure or stagnation pressure. Since dynamic
pressure is referenced to static pressure, it is neither gauge nor absolute; it is a differential
pressure.
While static gauge pressure is of primary importance to determining net loads on pipe
walls, dynamic pressure is used to measure flow rates and airspeed. Dynamic pressure can be
measured by taking the differential pressure between instruments parallel and perpendicular to
the flow. Pitot-static tubes, for example perform this measurement on airplanes to determine
airspeed. The presence of the measuring instrument inevitably acts to divert flow and create
turbulence, so its shape is critical to accuracy and the calibration curves are often non-linear.

Sphygmomanometer

Barometer

Altimeter

Pitot tube

MAP sensor Instruments
Many instruments have been invented to measure pressure, with different advantages and
disadvantages. Pressure range, sensitivity, dynamic response and cost all vary by several orders
of magnitude from one instrument design to the next. The oldest type is the liquid column (a
vertical tube filled with mercury) manometer invented by Evangelista Torricelli in 1643. The UTube was invented by Christian Huygens in 1661.
Hydrostatic
Hydrostatic gauges (such as the mercury column manometer) compare pressure to the
hydrostatic force per unit area at the base of a column of fluid. Hydrostatic gauge measurements
are independent of the type of gas being measured, and can be designed to have a very linear
calibration. They have poor dynamic response.
Piston
Piston-type gauges counterbalance the pressure of a fluid with a solid weight or a spring. For
example, dead-weight testers used for calibration or tire-pressure gauges.
Liquid column
The difference in fluid height in a liquid column manometer is proportional to the
pressure difference. Liquid column gauges consist of a vertical column of liquid in a tube whose
ends are exposed to different pressures. The column will rise or fall until its weight is in
equilibrium with the pressure differential between the two ends of the tube. A very simple
version is a U-shaped tube half-full of liquid, one side of which is connected to the region of
interest while the reference pressure (which might be the atmospheric pressure or a vacuum) is
applied to the other. The difference in liquid level represents the applied pressure. The pressure
exerted by a column of fluid of height h and density ρ is given by the hydrostatic pressure
equation, P = hgρ. Therefore the pressure difference between the applied pressure Pa and the
reference pressure P0 in a U-tube manometer can be found by solving Pa − P0 = hgρ. If the fluid
being measured is significantly dense, hydrostatic corrections may have to be made for the
height between the moving surface of the manometer working fluid and the location where the
pressure measurement is desired.
Although any fluid can be used, mercury is preferred for its high density (13.534 g/cm3)
and low vapour pressure. For low pressure differences well above the vapour pressure of water,
water is commonly used (and "inches of water" is a common pressure unit). Liquid-column
pressure gauges are independent of the type of gas being measured and have a highly linear
calibration. They have poor dynamic response. When measuring vacuum, the working liquid
may evaporate and contaminate the vacuum if its vapor pressure is too high. When measuring
liquid pressure, a loop filled with gas or a light fluid must isolate the liquids to prevent them
from mixing. Simple hydrostatic gauges can measure pressures ranging from a few Torr (a few
100 Pa) to a few atmospheres. (Approximately 1,000,000 Pa)
A single-limb liquid-column manometer has a larger reservoir instead of one side of the U-tube
and has a scale beside the narrower column. The column may be inclined to further amplify the
liquid movement. Based on the use and structure following type of manometers are used[2]
1. Simple Manometer
2. Micro manometer
3. Differential manometer
4. Inverted differential manometer
A McLeod gauge, drained of mercury
McLeod gauge
A McLeod gauge isolates a sample of gas and compresses it in a modified mercury manometer
until the pressure is a few mmHg. The gas must be well-behaved during its compression (it must
not condense, for example). The technique is slow and unsuited to continual monitoring, but is
capable of good accuracy.
Useful range: above 10-4 torr [3] (roughly 10-2 Pa) as high as 10−6 Torr (0.1 mPa),
0.1
mPa is the lowest direct measurement of pressure that is possible with current
technology. Other vacuum gauges can measure lower pressures, but only indirectly by
measurement of other pressure-controlled properties.
These indirect measurements must be calibrated to SI units via a direct measurement,
most commonly a McLeod gauge.[4]
Aneroid
Aneroid gauges are based on a metallic pressure sensing element which flexes elastically
under the effect of a pressure difference across the element. "Aneroid" means "without fluid,"
and the term originally distinguished these gauges from the hydrostatic gauges described above.
However, aneroid gauges can be used to measure the pressure of a liquid as well as a gas, and
they are not the only type of gauge that can operate without fluid. For this reason, they are often
called mechanical gauges in modern language. Aneroid gauges are not dependent on the type of
gas being measured, unlike thermal and ionization gauges, and are less likely to contaminate the
system than hydrostatic gauges. The pressure sensing element may be a Bourdon tube, a
diaphragm, a capsule, or a set of bellows, which will change shape in response to the pressure of
the region in question. The deflection of the pressure sensing element may be read by a linkage
connected to a needle, or it may be read by a secondary transducer. The most common secondary
transducers in modern vacuum gauges measure a change in capacitance due to the mechanical
deflection. Gauges that rely on a change in capacitances are often referred to as Baratron gauges.
Bourdon
Membrane-type manometer
A Bourdon gauge uses a coiled tube, which, as it expands due to pressure increase causes
a rotation of an arm connected to the tube. In 1849 the Bourdon tube pressure gauge was
patented in France by Eugene Bourdon.
The pressure sensing element is a closed coiled tube connected to the chamber or pipe in
which pressure is to be sensed. As the gauge pressure increases the tube will tend to uncoil,
while a reduced gauge pressure will cause the tube to coil more tightly. This motion is
transferred through a linkage to a gear train connected to an indicating needle. The needle is
presented in front of a card face inscribed with the pressure indications associated with particular
needle deflections. In a barometer, the Bourdon tube is sealed at both ends and the absolute
pressure of the ambient atmosphere is sensed. Differential Bourdon gauges use two Bourdon
tubes and a mechanical linkage that compares the readings.
In the following illustrations the transparent cover face of the pictured combination
pressure and vacuum gauge has been removed and the mechanism removed from the case. This
particular gauge is a combination vacuum and pressure gauge used for automotive diagnosis:
Indicator side with card and dial
Mechanical side with Bourdon tube

the left side of the face, used for measuring manifold vacuum, is calibrated in centimetres
of mercury on its inner scale and inches of mercury on its outer scale.

the right portion of the face is used to measure fuel pump pressure and is calibrated in
fractions of 1 kgf/cm² on its inner scale and pounds per square inch on its outer scale.
[edit] Mechanical details
Mechanical details
Stationary parts:

A: Receiver block. This joins the inlet pipe to the fixed end of the Bourdon tube (1) and
secures the chassis plate (B). The two holes receive screws that secure the case.

B: Chassis plate. The face card is attached to this. It contains bearing holes for the axles.

C: Secondary chassis plate. It supports the outer ends of the axles.

D: Posts to join and space the two chassis plates.
Moving Parts:
1. Stationary end of Bourdon tube. This communicates with the inlet pipe through the
receiver block.
2. Moving end of Bourdon tube. This end is sealed.
3. Pivot and pivot pin.
4. Link joining pivot pin to lever (5) with pins to allow joint rotation.
5. Lever. This an extension of the sector gear (7).
6. Sector gear axle pin.
7. Sector gear.
8. Indicator needle axle. This has a spur gear that engages the sector gear (7) and extends
through the face to drive the indicator needle. Due to the short distance between the
lever arm link boss and the pivot pin and the difference between the effective radius of
the sector gear and that of the spur gear, any motion of the Bourdon tube is greatly
amplified. A small motion of the tube results in a large motion of the indicator needle.
9. Hair spring to preload the gear train to eliminate gear lash and hysteresis.
Diaphragm
A pile of pressure capsules with corrugated diaphragms in an aneroid barograph.
A second type of aneroid gauge uses the deflection of a flexible membrane that separates
regions of different pressure. The amount of deflection is repeatable for known pressures so the
pressure can be determined by using calibration. The deformation of a thin diaphragm is
dependent on the difference in pressure between its two faces. The reference face can be open to
atmosphere to measure gauge pressure, open to a second port to measure differential pressure, or
can be sealed against a vacuum or other fixed reference pressure to measure absolute pressure.
The deformation can be measured using mechanical, optical or capacitive techniques. Ceramic
and metallic diaphragms are used.
Useful range: above 10-2 Torr [5] (roughly 1 Pa)
For absolute measurements, welded pressure capsules with diaphragms on either side are often
used.
Shape:

Flat

corrugated

flattened tube

capsule
Bellows
In gauges intended to sense small pressures or pressure differences, or require that an
absolute pressure be measured, the gear train and needle may be driven by an enclosed and
sealed bellows chamber, called an aneroid, which means "without liquid". (Early barometers
used a column of liquid such as water or the liquid metal mercury suspended by a vacuum.) This
bellows configuration is used in aneroid barometers (barometers with an indicating needle and
dial card), altimeters, altitude recording barographs, and the altitude telemetry instruments used
in weather balloon radiosondes. These devices use the sealed chamber as a reference pressure
and are driven by the external pressure. Other sensitive aircraft instruments such as air speed
indicators and rate of climb indicators (variometers) have connections both to the internal part of
the aneroid chamber and to an external enclosing chamber.
Electronic pressure sensors
Main article: Pressure sensor

Piezoresistive Strain Gage
Uses the piezoresistive effect of bonded or formed strain gauges to detect strain due to
applied pressure.

Capacitive
Uses a diaghragm and pressure cavity to create a variable capacitor to detect
strain due to applied pressure.

Magnetic
Measures the displacement of a diaphragm by means of changes in inductance
(reluctance), LVDT, Hall Effect, or by eddy current principal.

Piezoelectric
Uses the piezoelectric effect in certain materials such as quartz to measure the
strain upon the sensing mechanism due to pressure.

Optical
Uses the physical change of an optical fiber to detect strain due applied pressure.

Potentiometric
Uses the motion of a wiper along a resistive mechanism to detect the strain caused by
applied pressure.

Resonant
Uses the changes in resonant frequency in a sensing mechanism to measure stress, or
changes in gas density, caused by applied pressure.
Thermal conductivity
Generally, as a real gas increases in density -which may indicate an increase in pressureits ability to conduct heat increases. In this type of gauge, a wire filament is heated by running
current through it. A thermocouple or Resistance Temperature Detector (RTD) can then be used
to measure the temperature of the filament. This temperature is dependent on the rate at which
the filament loses heat to the surrounding gas, and therefore on the thermal conductivity. A
common variant is the Pirani gauge which uses a single platinum filament as both the heated
element and RTD. These gauges are accurate from 10 Torr to 10−3 Torr, but they are sensitive to
the chemical composition of the gases being measured.
Two wire
One wire coil is used as a heater, and the other is used to measure nearby temperature due to
convection.
Pirani (one wire)
A Pirani gauge consists of a metal wire open to the pressure being measured. The wire is
heated by a current flowing through it and cooled by the gas surrounding it. If the gas pressure is
reduced, the cooling effect will decrease, hence the equilibrium temperature of the wire will
increase. The resistance of the wire is a function of its temperature: by measuring the voltage
across the wire and the current flowing through it, the resistance (and so the gas pressure) can be
determined. This type of gauge was invented by Marcello Pirani
Thermocouple gauges and thermistor gauges work in a similar manner, except a thermocouple
or thermistor is used to measure the temperature of the wire.
Useful range: 10-3 - 10 Torr [6] (roughly 10-1 - 1000 Pa)
Ionization gauge
Ionization gauges are the most sensitive gauges for very low pressures (also referred to
as hard or high vacuum). They sense pressure indirectly by measuring the electrical ions
produced when the gas is bombarded with electrons. Fewer ions will be produced by lower
density gases. The calibration of an ion gauge is unstable and dependent on the nature of the
gases being measured, which is not always known. They can be calibrated against a McLeod
gauge which is much more stable and independent of gas chemistry.
Thermionic emission generate electrons, which collide with gas atoms and generate
positive ions. The ions are attracted to a suitably biased electrode known as the collector. The
current in the collector is proportional to the rate of ionization, which is a function of the
pressure in the system. Hence, measuring the collector current gives the gas pressure. There are
several sub-types of ionization gauge.
Useful range: 10-10 - 10-3 torr (roughly 10-8 - 10-1 Pa)
Most ion gauges come in two types: hot cathode and cold cathode, a third type exists
which is more sensitive and expensive known as a spinning rotor gauge, but is not discussed
here. In the hot cathode version an electrically heated filament produces an electron beam. The
electrons travel through the gauge and ionize gas molecules around them. The resulting ions are
collected at a negative electrode. The current depends on the number of ions, which depends on
the pressure in the gauge. Hot cathode gauges are accurate from 10−3 Torr to 10−10 Torr. The
principle behind cold cathode version is the same, except that electrons are produced in a
discharge created by a high voltage electrical discharge. Cold Cathode gauges are accurate from
10−2 Torr to 10−9 Torr. Ionization gauge calibration is very sensitive to construction geometry,
chemical composition of gases being measured, corrosion and surface deposits. Their calibration
can be invalidated by activation at atmospheric pressure or low vacuum. The composition of
gases at high vacuums will usually be unpredictable, so a mass spectrometer must be used in
conjunction with the ionization gauge for accurate measurement.[7]
Hot cathode
Bayard-Alpert hot cathode ionization gauge
A hot cathode ionization gauge is mainly composed of three electrodes all acting as a
triode, where the cathode is the filament. The three electrodes are a collector or plate, a filament,
and a grid. The collector current is measured in picoamps by an electrometer. The filament
voltage to ground is usually at a potential of 30 volts while the grid voltage at 180–210 volts DC,
unless there is an optional electron bombardment feature, by heating the grid which may have a
high potential of approximately 565 volts. The most common ion gauge is the hot cathode
Bayard-Alpert gauge, with a small ion collector inside the grid. A glass envelope with an
opening to the vacuum can surround the electrodes, but usually the Nude Gauge is inserted in
the vacuum chamber directly, the pins being fed through a ceramic plate in the wall of the
chamber. Hot cathode gauges can be damaged or lose their calibration if they are exposed to
atmospheric pressure or even low vacuum while hot. The measurements of a hot cathode
ionization gauge are always logarithmic.
Electrons emitted from the filament move several times in back and forth movements
around the grid before finally entering the grid. During these movements, some electrons collide
with a gaseous molecule to form a pair of an ion and an electron (Electron ionization). The
number of these ions is proportional to the gaseous molecule density multiplied by the electron
current emitted from the filament, and these ions pour into the collector to form an ion current.
Since the gaseous molecule density is proportional to the pressure, the pressure is estimated by
measuring the ion current.
The low pressure sensitivity of hot cathode gauges is limited by the photoelectric effect.
Electrons hitting the grid produce X-rays that produce photoelectric noise in the ion collector.
This limits the range of older hot cathode gauges to 10-8 Torr and the Bayard-Alpert to about 1010 Torr. Additional wires at cathode potential in the line of sight between the ion collector and
the grid prevent this effect. In the extraction type the ions are not attracted by a wire, but by an
open cone. As the ions cannot decide which part of the cone to hit, they pass through the hole
and form an ion beam. This ion beam can be passed on to a

Faraday cup

Microchannel plate detector with Faraday cup

Quadrupole mass analyzer with Faraday cup

Quadrupole mass analyzer with Microchannel plate detector Faraday cup

ion lens and acceleration voltage and directed at a target to form a sputter gun. In this
case a valve lets gas into the grid-cage.
See also: Electron ionization
Cold cathode
There are two subtypes of cold cathode ionization gauges: the Penning gauge (invented
by Frans Michel Penning), and the Inverted magnetron, also called a Redhead gauge. The
major difference between the two is the position of the anode with respect to the cathode. Neither
has a filament, and each may require a DC potential of about 4 kV for operation. Inverted
magnetrons can measure down to 1x10-12 Torr. Such gauges cannot operate if the ions
generated by the cathode recombine before reaching the anodes. If the mean-free path of the gas
within the gauge is smaller than the gauge's dimensions, then the electrode current will
essentially vanish. A practical upper-bound to the detectable pressure is, for a Penning gauge, of
the order of 10-3 Torr.Similarly, cold cathode gauges may be reluctant to start at very low
pressures, in that the near-absence of a gas makes it difficult to establish an electrode current particularly in Penning gauges which use an axially symmetric magnetic field to create path
lengths for ions which are of the order of metres. In ambient air suitable ion-pairs are
ubiquitously formed by cosmic radiation; in a Penning gauge design features are used to ease the
set-up of a discharge path. For example, the electrode of a Penning gauge is usually finely
tapered to facilitate the field emission of electrons.
Maintenance cycles of cold cathode gauges is generally measured in years, depending on
the gas type and pressure that they are operated in. Using a cold cathode gauge in gases with
substantial organic components, such as pump oil fractions, can result in the growth of delicate
carbon films and shards within the gauge which eventually either short-circuit the electrodes of
the gauge, or impede the generation of a discharge path.
Pressure gauges are either direct- or indirect-reading. Hydrostatic and elastic gauges measure
pressure are directly influenced by force exerted on the surface by incident particle flux, and are
called direct reading gauges. Thermal and ionization gauges read pressure indirectly by
measuring a gas property that changes in a predictable manner with gas density. Indirect
measurements are susceptible to more errors than direct measurements.

Dead weight tester

McLeod

mass spec + ionization
When fluid flows are not in equilibrium, local pressures may be higher or lower than the
average pressure in a medium. These disturbances propagate from their source as longitudinal
pressure variations along the path of propagation. This is also called sound. Sound pressure is the
instantaneous local pressure deviation from the average pressure caused by a sound wave. Sound
pressure can be measured using a microphone in air and a hydrophone in water. The effective
sound pressure is the root mean square of the instantaneous sound pressure over a given interval
of time. Sound pressures are normally small and are often expressed in units of microbar.

frequency response of pressure sensors

resonance
UNIT IV
Application in industrial systems: Thermistor control of quench oil temperature –
proportional mode pressure control system – strip tension controller – automatic
weighing system – control of relative humidity in a textile moistening process –
warehouse humidity controller.
SECTION A
1) List out Tension Controller Capabilities?

Quick installation and setup

Electric and pneumatic outputs

Rugged steel, custom 2-piece enclosure provides full access to all interior circuit cards
and components

Wide tension range without recalibration

Plug-in option cards

Many options available
2) List out some warehouse humidity?
Heated and unheated general warehouse, Refrigerated warehouse, Controlled humidity
warehouse.
SECTION B
1)WHAT IS THERMISTOR?
Temperature, pressure, flow, and level are the four most common process
variables. Similar to temperature, pressure is another key process variable because
pressure provides a critical condition for boiling, chemical reaction, distillation,
extrusion, vacuuming, and air conditioning.
Poor pressure control can cause major safety, quality, and productivity problems.
Overly high pressure inside a sealed vessel can cause an explosion. Therefore, it is
highly desirable to keep pressure in good control and maintained within its safety
limits.
(1)THERMISTOR APPLICATIONS?
Multiple gas lines may draw gas from a master line. When the load changes, they will interact
with each other.
Steam generators in co-generation plants have to deal with large steam load changes due to
demand changes.
Pressure in municipal gas grids or a product powder transport system have large and varying
time delays.
(2)WHAT IS THERMISTOR SPEED CONSIDERATION?
Since the pressure loop requires fast sample and control update rates, the PC-based
MFA control system using an HMI or OPC interface may not be fast enough to control
pressure loops. Embedded MFA control products or dedicated I/O cards in the PC will
provide sufficient sample rates for pressure control. CyboCon HS, CyboCon CE,
CyboCon Dragon, and all embedded MFA control products can be used for pressure
control.
(3)WHAT IS THERMISTOR NOISE CONSIDERATION?
Pressure loops are typically noisy. That means, the pressure PV may jump up and down due
to the nature of the pressure loop and the pressure sensor used. Low-pass filters can be used to
screen the high-frequency noise. Since the MFA controller is not noise-sensitive, a filter may not
be required unless the S/N ratio (signal-to-noise ratio) is so high that the control performance is
obviously affected. Some MFA control products like Cabochon can have a user-entry field to
specify when the PV is noisy.
(4)GIVE A SHORT NOTE ON PRESSURE CONTROL?
Pressure is another key process variable because pressure provides a critical condition for
boiling, chemical reaction, distillation, extrusion, vacuuming, and air conditioning. Poor pressure
control can cause major safety, quality, and productivity problems. Overly high pressure inside a
sealed vessel can cause an explosion. Therefore, it is highly desirable to keep pressure in good
control and maintained within its safety limits.
SECTION C
1)EXPLAIN THE PRESSURE CONTROL SYSTEM?
PressureControl
Introduction
Temperature, pressure, flow, and level are the four most common process
variables.
Similar to temperature, pressure is another key process variable because
pressure provides a critical condition for boiling, chemical reaction, distillation,
extrusion, vacuuming, and air conditioning. Poor pressure control can cause major
safety, quality, and productivity problems. Overly high pressure inside a sealed vessel
can cause an explosion. Therefore, it is highly desirable to keep pressure in good control
and
Why
maintained
within
Pressure
Control
its
Can
safety
Be
limits.
Difficult
The many reasons why a pressure loop is difficult to control are listed and described in
the following table:
Reason
Example
Control Headache
Nonlinear
Natural gas pipeline. Pressure of a A PID or model-based controller
fluidize-bed boiler. Gas mixing may work well in its linear range
plant.
and fail in its nonlinear range.
Multivariable
Multiple gas lines may draw gas A multivariable process cannot be
control
from a master line. When the load effectively controlled
by using
changes, they will interact with SISO controllers due to interactions
each other.
Large
among the variables.
load Steam generators in co-generation Load changes can cause major
changes
plants have to deal with large disturbances to pressure.
steam load changes due to demand
changes.
Large
varying
and Pressure in municipal gas grids or PID cannot effectively control a
time- a product powder transport system process with large and varying time
delays
have large and varying time delays. delays.
High-speed and The pressure field and Mach speed Due to the poor frequency domain
open-loop
value of an ultra-sonic wind-tunnel behavior of this process, tying to
oscillating
used in the aerospace industry is control an open-loop oscillating
open-loop oscillating.
Nonlinear
high-speed
MFA
loop can be a nightmare.
and Vacuum vessels used in thin film It is desirable to reach the vacuum
or material deposition.
Control
state but the process is nonlinear.
Solution
The following table provides a roadmap to allow you to select the appropriate MFA
controller to solve a specific pressure control problem.
Reason
Selected MFA Controller
Nonlinear
Nonlinear MFA controller or Nonlinear
Robust MFA controller.
What Can This MFA Do?
MFA
controls
extremely
nonlinear processes with no nonlinear
characterization required. Robust MFA
forces the pressure to stay inside the
desired boundary.
Multivariable MIMO MFA controller or MIMO
control
controls
multivariable
Feedback/Feedforward MFA processes. Interactions among pressure
controller.
Large
MFA
zones can be decoupled.
load Feedback/Feedforward MFA Feedforward MFA makes quick control
changes
controller or Robust MFA adjustments to compensate for the load
controller.
changes. Robust MFA forces the pressure
to stay inside the desired boundary.
Large
and Anti-delay MFA controller or Anti-delay MFA can effectively control
varying time- Time-varying
delays
controller.
MFA processes with large time delays. Timevarying MFA can control processes with
large and varying time delays.
High-speed
High-speed Flex-phase MFA After choosing a phase-angle during
and open-loop controller or Nonlinear Flex- configuration, the Flex-phase MFA can
oscillating
phase MFA controller.
effectively control processes with bad
behavior in the frequency domain.
Nonlinear and High-speed Nonlinear MFA After choosing a Nonlinearity factor
high-speed
controller.
during configuration, the Nonlinear MFA
can effectively control this process with
changing nonlinear characteristics.
Speed
Considerations
Since the pressure loop requires fast sample and control update rates, the PC-based MFA
control system using an HMI or OPC interface may not be fast enough to control
pressure loops. Embedded MFA control products or dedicated I/O cards in the PC will
provide sufficient sample rates for pressure control. CyboCon HS, CyboCon CE,
CyboCon Dragon, and all embedded MFA control products can be used for pressure
control.
NoiseConsiderations
Pressure loops are typically noisy. That means, the pressure PV may jump up and
down due to the nature of the pressure loop and the pressure sensor used. Low-pass
filters can be used to screen the high-frequency noise. Since the MFA controller is not
noise-sensitive, a filter may not be required unless the S/N ratio (signal-to-noise ratio) is
so high that the control performance is obviously affected. Some MFA control products
like CyboCon can have a user-entry field to specify when the PV is noisy.
Summary
Based on the core MFA control method, various MFA controllers have
been developed to solve specific control problems. This applies to pressure control
applications as well. The roadmap above is a guide for selecting the appropriate MFA
controller
to
keep
the
pressure
loop
under
good
control.
CaseStudies
To read more about implementations of CyboSoft’s MFA pressure control solutions,
click on the following case studies:
1)EXPLAIN THE STRIP TENSION CONTROLLER?
SteadyWeb™ Automatic Tension Controller
The most versatile, easy-to-use automatic tension
controller available. Use in unwind, intermediate, or rewind
tension zones. SteadyWeb controls clutches, brakes, and
variable speed drives. All operator adjustments are on one
board to simplify set-up. Optional functions include taper
tension, dual transducer input, DC and pulse tachometer
inputs, and more. System status lights allow the operator to
see the operating mode at a glance.
Tension Controller Capabilities

Quick installation and setup

Electric and pneumatic outputs

Rugged steel, custom 2-piece enclosure provides full access to all interior circuit cards
and components

Wide tension range without recalibration

Plug-in option cards

Many options available
Available Outputs
D - 0-10 VDC compensated output for use with adjustable speed DC and AC drives. The
output is electrically isolated for compatibility and reliability. Used in all tension zones;
unwind, rewind and intermediate.
V - 0-90 VDC output. For use in all types of electrical brakes and clutches, including eddy
current clutches. Also available with 24 and 45 VDC output. Commonly used in the unwind
or rewind zones.
P - 0-75 psi output for use with pneumatic clutches and brakes. Most commonly used in the
unwind and rewind zones. System includes internal air filter and regulator (80-120 psi input
pressure).
1) DRAW
ANEATLY
DIAGRAM
QUENCH
TEMP
OF
OIL
TEMPERATURE?
a)HEAT
TREATMENT
APPLICATIONS
UK-100 GP is a general purpose program controller for furnace, kiln, oven & bath etc.
The advantages of program controller includes improved quality, power saving &
higher throughputs because of less reruns. The multi-zone option is available to cater to
large
furnace
systems
including
the
oil
fired
SENSOR
INPUT:
Thermo-couple
of
any
type,
RTD
,
mA,
mV
TEMPERATURE
0.01
type.
/
,
Thermistor
RESOLUTION:
0.1
/
1
C
depending
on
the
range.
ss
CONTROL
PID
OUTPUT:
ACTION
with
fully
programmable
:
parameters
Time proportioning / Up-Down action for valve positioning / 4 to 20 mA current
proportioning.The control outputs drive the SSR's or SCR drives as per the requirements.
PROGRAM
STORAGE:
40
programs
(99
steps
/
program).
Every step includes Temperature , Rate ( in C per min or hour) , Soak period , Operator call &
Event Relay setting. Number of laps for the whole program is also settable. All the programs
are
stored
in
MULTI
Up
non-volatile
EEPROM.
CHANNEL
to
4
channels.
Each
channel
can
OPTION:
be
profile
or
fixed
set
STANDARD
point
type.
FACILITIES:
Auto hold, Manual hold, Programmable operator call hold, Skip step, Auto start with real
time, Online alteration, Auto/Man selection, Abort, Repeat, Power fail Auto restart.
ALARM:
Programmable
alarm
AUXILLARY
limits
during
OUTPUTS
ramp
&
&
soak.
INTERLOCKS:
Upto 4 event relays can be provided for auxiliary functions & upto 4 digital inputs can be
used for interlock purposes. The numbers can be increased if there is a requirement.
FRONT
PANEL:
Combi display with 2 sets of 4 LED displays , 16 x 2 alphanumeric backlit LCD display & 8
Nos virtual LED indicators. The keypad is 5 key high quality sealed membrane type.
REAL
TIME
CLOCK
&
CALENDAR:
Provided
with
battery
back
up.
INTERFACE:
RS-232
C
for
linking
PC/Serial
printer.
RS-485
for
networking
Modbus
multiple
controllers
to
RTU
‘ukcom’
software
is
provided
PC.
compatible.
along
with
these
options.
Choice is available with the user to either select PC/Printer in the parameter menu.
RECORDER
INTERFACE:
Analog retransmission signal ( 4 to 20 mA / 0 to 1 Vdc) is also available (as option) for
linking
the
POWER
:
ENCLOSURE:
b)
controller
Universal
power
96
X
TEXTILE
90
Vac
96
to
to
X
265
Vac
110
PROCESSING
recorder.
,
50/60
(in
Hz
mm)
APPLICATIONS:
UK-100 TEX is configured for textile processing applications like Jet dyeing, Yarn
dyeing, Beaker dyeing, Winch Dyeing, Beam Dyeing, Multi tank applications , Soft flow
&
Dye
An
House
example
is
automation.
illustrated
below:
The multi tank controller , in general , is capable of performing the following tasks:
1. Filling options for dyeing tank, stock tank & color addition/ expansion tank:
Hot / cold fill Fill up to particular level (each tank having 0,1,2,3 levels)
2. Stock tank individual functions: Stirring, Heating, Adding chemicals, Draining
3. Dyeing tank individual functions : Forward / Reverse circulation, heating/cooling to follow
the
set
profile
,
pressurize/depressurize,
and
drain
washing
4.Combined functions: Transfer from stock tank to dyeing tank & vice versa, Rinsing.
5.Dozing functions: Dozing the dyeing tank using expansion/color tank in rate controlled
manner.
6.Allied functions: Back cooler, controlled pressurization using pressure sensor, variable
input (forward, reverse, stop conditions) to the inverter controlling the pump.
The functions are in terms of codes which are entered in the program. Each code consists of
its
own
c)
logic,
CARBON
interlock
%
&
PROGRAM
outputs.
CONTROLLER:
UK-100 CP is employed in ‘carburizing & hardening ‘ applications mainly in
automobile
parts
manufacturing,
machine
tool
industry
etc.
Generally, there are 3 sensor inputs : Thermo couple for furnace temperature Carbon potential
sensor
(
Oxygen
sensor)
&
RTD
for
quenching
temperature.
The controller has built in Carbon % Vs Millivolt (of Oxygen sensor)
table at various temperatures. The software provides direct readout as well as setting in
carbon %. The Control outputs are furnace temperature control, Carbon % control &
quenching temperature control. Each of these can be either PID type or ON/OFF type
depending
on
the
actuators
&
the
system.
Restart with door closing signal & remote release (from an initial hold condition) button for
the operator are provided. Also. available are the event relays for door opening, agitator motor
& spare function. A typical program consists of several steps ( up to 50 ) with each step
having programmed temperature , carbon % , duration , operator call , event relays & quench
temperature. The entire process along with auxiliary functions can be easily programmed by
the
plant
personnel.
RS-232 C /RS-485 interface along with the requisite software is available as option.
2)EXPLAIN THE WAREHOUSE HUMIDITY CONTROLLER?
Overview
Warehouses, defined here, are facilities that provide a proper environment for the
purpose of storing goods and materials that require protection from the elements. Warehouses
must be designed to accommodate the loads of the materials to be stored, the associated handling
equipment, the receiving and shipping operations and associated trucking, and the needs of the
operating personnel. The design of the warehouse space should be planned to best accommodate
business service requirements and the products to be stored/handled. The economics of modern
commercial warehouses dictate that goods are processed in minimal turnaround time.
The different types of warehouses include:
 Heated
and unheated general warehouses—provide space for bulk, rack, and bin storage,
aisle space, receiving and shipping space, packing and crating space, and office and
toilet space;
 Refrigerated
warehouses—preserve the quality of perishable goods and general supply
materials that require refrigeration. Includes freeze and chill space, processing
facilities, and mechanical areas; and
 Controlled
humidity (CH) warehouses—similar to general warehouses except that they
are constructed with vapor barriers and contain humidity control equipment to maintain
humidity at desired levels.
Special-designed warehouses meeting strict requirements can also provide liquid storage (fuel
and nonpropellants), flammable and combustible storage, radioactive material storage, hazardous
chemical storage, and ammunition storage.
Features already now common in warehouse designs are higher bays, sophisticated
materials-handling equipment, broadband connectivity access, and more distribution networks. A
wide range of storage alternatives, picking alternatives, material handling equipment and
software exist to meet the physical and operational requirements of the warehouse. Warehouse
spaces must also be flexible to accommodate future operations and storage needs as well as
mission changes.
Building Attributes
Being utilitarian facilities, warehouse designers should focus on making the warehouse
spaces functional and efficient, while providing a safe and comfortable environment for the
workers to increase productivity and control, reduce operating costs, and improve customer
service. Even warehouses have to maintain a corporate image and provide for worker
satisfaction. Building image and aesthetics, landscaping, and worker safety and comfort, become
important issues in competitive real estate markets.
 Be designed
based on current and future needs.
o Facilitate
changes in business/agency growth, and size/population of office and
warehouse spaces within the building. Warehouse space should be easily
adapted to new functions such as office (on ground or upper levels), computer
centers, or light industrial/fabrication.
o Accommodate
need for future loading docks, truck space, and car parking spaces
if space configuration changes through effective site design.
o Address
material handling technologies and business practice, such as "just-in-
time" storage, which have fundamentally changed operation of warehouses and
distribution centers, and will continue to do so.
o Include
roof design with built-in extra structural capacity to handle addition of
future rooftop equipment.
o Be
designed with fire protection capacity to accommodate storage of materials
with a greater fire hazard, especially needed with high plastic product content
or packaging, and plastic shrink-wrapped pallets.
 Maximize
utilization of space while providing adequate circulation paths for personnel
and material handling equipment such as forklift trucks.
o Use higher
 Optimize
bays to take advantage of height allowances in the space.
layout and configuration for the warehouse operation, including efficient
circulation and material handling and storage processes.
 Relate
interior and exterior receiving and shipping operations to the process flow of
goods through the warehouse.
 Receiving
and shipping are best separated to avoid congestion at the loading dock areas
in the building, and in the truck maneuvering areas.
 Alternative material
handling methods will determine other building aspects, such as aisle
widths, lighting design, need for mezzanine space, fire protection, and egress design.
Businesses will often use different methods of storage handling simultaneously for
different products.
C. Durable/Functional
 Be
planned to accommodate loads of stored materials as well as associated handling
equipment.
o Design
of warehouses is to be based on the dead and live load requirements of the
structure as it will be built. Snow, wind, and seismic loads shall be considered
where they are applicable. Racking in seismic areas must be built stronger and
be better braced.
o Wind
uplift can cause great damage to roofs and metal roof copings at the roof
edge. Building codes recognize that wind velocity is greater across open areas,
typical for warehouse zones.
o Wind-driven
rain can easily penetrate the vast surface areas of the warehouse
walls. Design walls to permit any infiltrating water to evaporate harmlessly
without collecting in the wall cavities or damaging stored product.
o Proper
floor types are an important consideration in the design. General
warehouse space should be floored with a concrete slab to carry wheel loads
and withstand the abrasion generated by the continual use of hard rubber and
steel-wheeled forklift trucks. Consider adding hardeners and dustproofers to
protect the concrete. Consider using epoxy coating on concrete floors near
battery charging areas.
o Floor
flatness and levelness requirements are critical, especially for high ceilinged
space and safe operation of high-lifting equipment.
o Adequate
space must be provided on-site for truck maneuvering, truck storage if
the business owns a fleet, car parking for employees and future office
space/population expansion (which might be driven by higher rent for centercity office space), and landscaped areas.
 Be
designed to ensure that no structural member will interfere with the spacing of rail car
doors or truck berths at dock spaces. Dock heights on the truck side of the terminal
should be approximately 4'-4" above the pavement, with appropriate ramps at each
truck berth to bring the height of the truck bed in line with the dock height. Dock
heights on the rail side of the terminal should be approximately 3'-9" above the top of
the rail to ensure that the rail car floor is even with the dock floor. Dock widths and
areas inside exterior doors leading to dock space must be planned for maneuverability
of forklift trucks and other expected types of material handling equipment.
o Dock
heights on the truck side of the terminal should be approximately 4'-40"
above the pavement, with appropriate ramps, scissor lifts, or dock levelers at
each truck berth to safely bring the height of the truck bed in line with the dock
height.
o Tops
of doors should be high enough to accommodate full height pallet handling
from the highest trucks.
o Dock
heights on the rail side of the terminal should be approximately 3'-9" above
the top of the rail to ensure that the rail car floor is even with the dock floor.
o Dock
widths and areas inside exterior doors leading to dock space must be
planned for maneuverability of forklift trucks and other expected types of
material handling equipment. Consider using a non-slip finish on the concrete
floor near loading areas for safety.
D. Energy-Efficient
 Be
designed with passive solar concepts, solar geometry, and building load requirements
in mind.
 Possess
light colored roof to reflect a large percentage of solar radiation, reducing HVAC
loads, and energy consumption. First cost is also reduced, due to the smaller plant size
required. When a large roof area is anticipated, this effect can be significant, especially
for temperature controlled warehouses. Greater heat reflection will increase wroker
productivity in the summer.
 Be
planned with interior dock space in colder climates to reduce energy consumption and
provide more tolerable winter working conditions for dock workers.
 Use
ceiling mounted fans to reduce heat stratification and provide air movement, thus
increasing worker comfort in both summer and winter. Mount fans above highest
forklift level for worker safety.
 Consider
specifying white painted metal roof decking, thereby increasing ceiling surface
reflectivity, lighting efficiency, and worker comfort without any added energy cost.
 Use
energy-efficient fixtures, systems, and appliances, e.g., motion sensor instant-on
lighting systems, wherever feasible.
E. Safety/Security of Personnel and Material

Address the traditional life-safety and health concerns common to all buildings,
including measures to prevent occupational injuries and illnesses (work-related
musculoskeletal disorders (WMSD), trips, falls, etc.), ensure electrical safety, and
eliminate exposure to hazardous materials. The following operations have historically
contributed to significant numbers of warehouse injuries and are considered to be the
most hazardous: docks, powered industrial trucks, conveyors, materials storage,
manual lifting/handling, roof ladders and hatches, and charging stations. Other serious
operational safety problems include inadequate fire safety provisions, improper
blocking of exits and egress paths, chemical exposure, improper use of lockout
procedures, lack of ergonomics, and failure to wear personal protective equipment.

Incorporate proper signage to clearly warn of hazards or to direct personnel to take
precaution. The specific strategy for the warehouses signs must be determined early in
the facility design process.

Possess non-slip surface treatments on floors subject to wetting, such as outdoor docks,
to eliminate slips and falls to personnel.

Be designed with fire sprinkler systems engineered to cover the specific commodity
classification in the specific storage configuration for the planned warehouse. The
adequacy of the sprinkler system must be evaluated when changes occur that can
increase the hazard classification, such as introducing a new product line, using a
different packaging material, or changing from wood pallets to plastic pallets.

Include appropriate security systems incorporated into the overall warehouse design.
F. Health/Comfort
 Provide proper
 Provide
ventilation under all circumstances.
local exhaust for restrooms, kitchens, janitor's closets, copy rooms, battery-
charging areas, etc.
 Consider
installing CO2 sensors to provide real time monitoring of air quality.
 Integrate daylighting with
 Allow
the electric lighting system.
for natural lighting where possible. Provide lighting controls that turn off lights
when sufficient daylight exists. Consider dimming controls that continuously adjust
lighting levels to respond to daylight conditions.
 Consider
the different natural lighting designs for warehouses.
 Minimize HVAC
 Use
system noise in occupied space.
furnishings, chairs, and equipment that are ergonomically designed and approved for
that use.
 Design
equipment and furnishings reflective of healthy work practices in an effort to
eliminate repetitive motions as well as prevent strains and sprains.
 Strive
to create a 'sense of place' such that the warehouse has a unique character that
engenders a sense of pride, purpose, and dedication for individual workers and the
workplace community.
Examples of natural lighting designs for warehouse structures
G. Example Design and Construction Criteria
For GSA, the unit costs for this building type are based on the construction quality and
design features in the following table (PDF 187 KB, 14 pgs). This information is based on GSA's
benchmark interpretation and could be different for other owners.
Emerging Issues
Automated Storage and Retrieval Systems (AS/RS) are reshaping the ways in which
goods and services are manufactured, stored, and distributed. AS/RS have become a means to
control and immediately report the movement of material, providing a critical link in the chain of
information systems that control work-in-process, manufacturing schedules, and distribution.
AS/RS warehouses are designed for maximum storage and minimum personnel on site. They are
built for lower temperature operation with minimal heat and light needed, but require a tall
structure with super level floors.
In the private sector, competition, technology and e-commerce are forcing distributors to
look for ways to move larger quantities of their products more quickly and efficiently to the
consumer. Clustering distribution centers in a single geographic area is among the new trends.
There is also a move towards transportation specialization, such as companies that depend on
substantial parcel air transport, locating near Memphis, TN, while Columbus, OH rates higher
for companies focused on overland distribution.
Labor availability and technology advances are factors driving many companies to
consolidate their distribution systems into fewer but larger, regional facilities. However, not all
companies are consolidating their distribution centers: in many areas, the consolidation trend
itself is producing a new generation of smaller, local distribution centers. Experts say that new
logistical handling systems and greater outsourcing—in particular, the increased use of thirdparty logistics providers—seem to be driving this trend.New "flex" warehouses in well
landscaped industrial park settings for smaller businesses is a growing trend. These buildings
accommodate small businesses such as contractors, light industrial fabricators, and mechanics
that do not need exposure to heavy retail street traffic.
In older industrial areas, small warehouse buildings with low roofs, no longer suitable for
large single commercial users, are being repositioned and renovated as multi-tenant "flex"
warehouse buildings.Forces outside the parameters of the normal building project can generate
great changes in warehouse design. Examples include accelerated tax write-offs in the 1980's,
which enabled speculative construction of much larger buildings; again 1980's federal
regulations to permit much larger over-the-road trucks, which required commensurate changes to
site space given over to truck space; local real estate market prices, which often makes it
economically attractive for companies to relocate much of their corporate back office space at
their regional distribution center; increasingly tighter environmental and permitting processes,
which leaves the market to the larger developers, resulting in usually larger projects; and the
reclamation of former "brownfields" industrial sites for either new industrial or other uses.
INDUSTRIAL ROBOTIC SYSTEMS AND
MICROPROCESSOR BASED INDUSTRIAL APPLICATION
UNIT-V
Industrial Robotic Systems: Parts of robotic systems – Classifications of
roboticsystems –robotic system configurations – degrees of freedom of robotic
system – programming robotic systems – motions of robotic systems – sensor for
robotic systems – mechanical parts – controlsystems.Microprocessor based
industrial applications: Speed control of DC motor – measurement of physical
quantities – water level indicator – firing angle control of thyristor.
SECTION A
1.___________ probes are used to sense the water level
 The Copper
2. AARM stands for _____________
 Advanced Architecture Robot and Machine Motion
3. Two important sources of electric power for mobile robots are :
 solar cells and batteries
SECTION - B
1. WHAT ARE THE PARTS OF A ROBOTIC SYSTEMS?
The general categories of robot systems are:

Controller

Body

Mobility

Power

Sensors

Tools
2.DEFINE CONTROLLER OF ROBOTIC SYSTEM
The controller is the robot's brain and controls the robot's movements. It's usually a computer of
some type which is used to store information about the robot and the work environment and to
store and execute programs which operate the robot. The control system contains programs, data
algorithms, logic analysis and various other processing activities which enable the robot to
perform.
3.EXPLAIN THE WORKING OF WATER LEVEL INDICATOR:
The water level Controller is a reliable circuit, it takes over the task of indicating and Controlling
the water level in the overhead water tanks. The level of the water is displayed in the LED Bar
graph. The Copper probes are used to sense the water level. The probes are inserted into the
water
tank
which
is
to
be
monitored.
This water-level Controller-cum-alarm circuit is configured around the well-known 8 bit
Microprocessor 8085. It continuously monitors the overhead water level and display it and it also
switch Off the Motor when the tank fills and it will automatically switch On the Motor when the
water
level
is
low.
The Microprocessor will also indicate the water level over the LED display. All the input and
output functions are done through the Programmable Peripheral Interface IC 8255.
SECTION - C
1.EXPLAIN ABOUT PARTS OF ROBOTIC SYSTEM?
Robot Systems
Robots are comprised of several systems working together as a whole. The type of job the
robot does dictates what system elements it needs. The general categories of robot systems are:

Controller

Body

Mobility

Power

Sensors

Tools
Controller
The controller is the robot's brain and controls the robot's movements. It's usually a
computer of some type which is used to store information about the robot and the work
environment and to store and execute programs which operate the robot. The control system
contains programs, data algorithms, logic analysis and various other processing activities which
enable the robot to perform.
The picture above is an AARM Motion control system. AARM stands for Advanced
Architecture Robot and Machine Motion and it's a commercial product from American Robot for
industrial machine motion control. Industrial controllers are either non-servos, point-to-point
servos or continuous path servos. A non-servo robot usually moves parts from one area to
another and is called a "pick and place" robot. The non-servo robot motion is started by the
controller and stopped by a mechanical stop switch. The stop switch sends a signal back to the
controller which starts the next motion. A point-to-point servo moves to exact points so only the
stops in the path are programmed. A continous path servo is appropriate when a robot must
proceed on a specified path in a smooth, constant motion.
More sophisticated robots have more sophisticated control systems. The brain of the
Mars Sojourner rover was made of two electronics boards that were interconnected to each other
with Flex cables. One board was called the "CPU" board and the other the "Power" board and
each contained items responsible for power generation, power conditioning, power distribution
and control, analog and digital I/O control and processing, computing (i.e., the CPU), and data
storage (i.e., memory). The control boards for Sojourner are shown below. For more info, visit
Rover Control and Navigation at JPL.
Mobile robots can operate by remote control or autonomously. A remote control robot
receives instructions from a human operator. In a direct remote control situation, the robot relays
information to the operator about the remote environment and the operator then sends the robot
instructions based on the information received. This sequence can occur immediately (real-time)
or with a time delay. Autonomous robots are programmed to understand their environment and
take independent action based on the knowledge they posess. Some autonomous robots are able
to "learn" from their past encounters. This means they can identify a situation, process actions
which have produced successful/unsuccessful results and modify their behavior to optimize
success. This activity takes place in the robot controller.
Body
The body of a robot is related to the job it must perform. Industrial robots often take the
shape of a bodyless arm since it's job requires it to remain stationary relative to its task. Space
robots have many different body shapes such as a sphere, a platform with wheels or legs, or a
ballon, depending on it's job. The free-flying rover, Sprint Aercam is a sphere to minimize
damage if it were to bump into the shuttle or an astronaut. Some planetary rovers have solar
platforms driven by wheels to traverse terrestrial environments. Aerobot bodies are balloons that
will float through the atmosphere of other worlds collecting data. When evaluating what body
type is right for a robot, remember that form follows function.
Mobility
How do robots move? It all depends on the job they have to do and the environment they
operate in.
In the Water: Conventional unmanned, submersible robots are used
in science and industry throughout the oceans of the world. You
probably saw the Jason AUV at work when pictures of the Titanic discovery were broadcast.
To get around, automated underwater vehicles (AUV's) use propellers and rudders to
control their direction of travel. One area of research suggests that an underwater robot like
RoboTuna could propel itself as a fish does using it's natural undulatory motion. It's thought that
robots that move like fish would be quieter, more maneuverable and more energy efficient.
On Land: Land based rovers can move around on legs, tracks or
wheels. Dante II is a frame walking robot that is able to descend into
volcano craters by rapelling down the crater. Dante has eight legs; four
legs on each of two frames. The frames are separated by a track along
which the frames slide relative to each other. In most
cases Dante II has at least one frame (four legs) touching the ground. An
example of a track driven robot is Pioneer, a robot developed to clear rubble,
make maps and acquire samples at the Chornobyl Nuclear Reactor site.
Pioneer is track-driven like a small bulldozer which makes it suitable for
driving over and through rubble. The wide track footprint gives good
stability and platform capacity to deploy payloads.
Many robots use wheels for locomotion. One of the first US roving vehicles used for space
exploration went to the moon on Apollo 15 (July 30, 1971)
and was driven by astronauts David R. Scott and James B.
Irwin. Two other Lunar Roving Vehicles (LRV) also went to
the moon on Apollo 16 and 17. These rovers were battery
powered and had radios and antenna's just like the Mars
Pathfinder rover Sojourner. But unlike Sojourner, these
rovers were designed to seat two astronauts and be driven
like a dune buggy.
The Sojourner rover's wheels and suspension use a rocker-bogie system that is unique in
that it does not use springs. Rather, its joints rotate and conform to the contour of the ground,
which helps it traverse rocky, uneven surfaces. Six-wheeled vehicles can overcome obstacles
three times larger than those crossable by four-wheeled vehicles. For
example, one side of Sojourner could tip as much as 45 degrees as it
climbed over a rock without tipping over. The wheels are 13 centimeters
(5 inches) in diameter and made of aluminum. Stainless steel treads and
cleats on the wheels provide traction and each wheel can move up and down independently of all
the others.
In the Air/Space: Robots that operate in the air use engines and thrusters to get around. One
example is the Cassini, an orbiter on it's way to Saturn. Movement and
positioning is accomplished by either firing small thrusters or by
applying a force to speed up or slow down one or more of three
"reaction wheels." The thrusters and reaction wheels orient the
spacecraft in three axes which are maintained with great
precision. The propulsion system carries approximately 3000 kilograms
(6600 lbs) of propellant that is used by the main rocket engine to
change the spacecraft's velocity, and hence its course. A total velocity
change of over 2000 meters per second (6560 ft/s) is possible. In addition, Cassini will be
propelled on its way by two "gravity assist" flybys of Venus, one each of Earth and Jupiter, and
three dozen of Saturn's moon Titan. These planetary flybys will provide twenty times the
propulsion provided by the main engine.
Deep Space 1 is an experimental spacecraft of the future sent into
deep space to analyze comets and demonstrate new technologies
in space. One of it's new technologies is a solar electric (ion)
propulsion engine that provides about 10 times the specific
impulse of chemical propulsion. The ion engine works by giving
an electrical charge, or ionizing, a gas called xenon. The xenon is
electrically accelerated to the speed of about 30 km/second.
When the xenon ions are emitted at such a high speed as exhaust from the spacecraft, they push
the spacecraft in the opposite direction. The ion propulsion system requires a source of energy
and for DS1 the energy comes from electrical power generated by it's solar arrays.
Power
Power for industrial robots can be electric, pneumatic or hydraulic. Electric motors are
efficient, require little maintenance, and aren't very noisy. Pneumatic robots use compressed air
and come in a wide variety of sizes. A pneumatic robot requires another source
of energy such as electricity, propane or gasoline to provide the compressed
air. Hydraulic robots use oil under pressure and generally perform heavy duty
jobs. This power type is noisy, large and heavier than the other power sources.
A hydraulic robot also needs another source of energy to move the fluids
through its components. Pneumatic and hydraulic robots require maintenance
of the tubes, fittings and hoses that connect the components and distribute the
energy.
Two important sources of electric power for mobile robots are
solar cells and batteries. There are lots of types of batteries like carbonzinc, lithium-ion, lead-acid, nickel-cadmium, nickel-hydrogen, silver
zinc and alkaline to name a few. Battery power is measured in amphours which is the current (amp) multiplied by the time in hours that
current is flowing from the battery. For example, a two amp hour battery
can supply 2 amps of current for one hour. Solar cells make electrical
power from sunlight. If you hook enough solar cells together in a solar
panel you can generate enough power to run a robot. Solar cells are also
used as a power source to recharge batteries.
Deep space probes must use alternate power sources because beyond
Mars existing solar arrays would have to be so large as to be infeasible.
The lifespan of batteries is exceeded at these distances also. Power
for deep space probes is traditionally generated by radioisotope
thermoelectric generators or RTGs, which use heat from the natural decay of plutonium to
generate direct current electricity. RTGs have been used on 25 space missions including Cassini,
Galileo, and Ulysses.
Sensors
Sensors are the perceptual system of a robot and measure physical quantities like contact,
distance, light, sound, strain, rotation, magnetism, smell, temperature, inclination, pressure, or
altitude. Sensors provide the raw information or signals that must be processed through the
robot's computer brain to provide meaningful information. Robots are equipped with sensors so
they can have an understanding of their surrounding environment and make changes in their
behavior based on the information they have gathered.
Sensors can permit a robot to have an adequate field of view, a range of detection and the
ability to detect objects while operating in real or near-real time within it's power and size limits.
Additionally, a robot might have an acoustic sensor to detect sound, motion or location, infrared
sensors to detect heat sources, contact sensors, tactile sensors to give a sense of touch, or
optical/vision sensors. For most any environmental situation, a robot can be equipped with an
appropriate sensor. A robot can also monitor itself with sensors.
The Big Signal robot NOMAD uses sensing instruments like a
camera, a spectrometer and a metal-detector. The high resolution video
camera can identify dark objects (rocks, meterorites) against the white
background of the Antarctic snow. The variations in color and shade allow
the robot to tell the difference between dark grey rocks and shadows. Nomad uses a laser range
finder to measure the distance to objects and a metal detector to help determine the composition
of the objects if finds.
Very complex robots like Cassini have full sets of sensing equipment much like human
senses. It's skeleton must be light and sturdy, able to withstand extreme temperatures and
monitor those temperatures. Cassini determines it's location by using three hemisperical resonant
gyroscopes or HRG's which measures quartz crystal vibrations. The eyes of Cassini are the
Imaging Science Subsystem (ISS) which can take pictures in the visible range, the nearultraviolet and near-infrared ranges of the electromagnetic spectrum.
Tools
As working machines, robots have defined job duties and carry all the tools they need to
accomplish their tasks onboard their bodies. Many robots carry their tools at the end of a
manipulator. The manipulator contains a series of segments, jointed or sliding relative to one
another for the purpose of moving objects. The manipulator includes the arm, wrist and endeffector. An end-effector is a tool or gripping mechanism attached to the end of a robot arm to
accomplish some task. It often encompasses a motor or a driven mechanical device. An endeffector can be a sensor, a gripping device, a paint gun, a drill, an arc welding device, etc. There
are many examples of robot tools that you will discover as you examine the literature associated
with this site. To get you going, two good examples are listed below.
Tools are unique to the task the robot must perform. The goal of the robot
mission Stardust is to capture both cometary samples and interstellar dust.
The trick is to capture the high velocity comet and dust particles without
physically changing them. Scientists developed aerogel, a silicon-based
solid with a porous, sponge-like structure in which 99.8 percent of the volume is empty space.
When a particle hits the aerogel, it buries itself in the material, creating a carrot-shaped track up
to 200 times its own length. This slows it down and brings the sample to a relatively gradual
stop. Since aerogel is mostly transparent - with a distinctive smoky blue cast - scientists will use
these tracks to find the tiny particles.
Robonaut has one of the many ground breaking dexterous robot hands developed over the
past two decades. These hand devices make it possible for a robot
manipulator to grasp and manipulate objects that are not designed to be
robotically compatible. While several grippers have been designed for space
use and some even tested in space, no dexterous robotic hand has been
flown in Extra Vehicular Activity (EVA) conditions. The Robonaut Hand is one of the first
under development for space EVA use and the closest in size and capability to a suited
astronaut's hand. The Robonaut Hand has a total of fourteen degrees of freedom. It consists of a
forearm which houses the motors and drive electronics, a two degree of freedom wrist, and a five
finger, twelve degree of freedom hand. The forearm, which measures four inches in diameter at
its base and is approximately eight inches long, houses all fourteen motors, 12 separate circuit
boards, and all of the wiring for the hand.
2)CLASSIFICATION OF ROBOTIC SYSTEMS?
CLASSIFICATION: CLASSIFIED INTO SIX CATEGORIES
 ARM GEOMETRY: RECTANGULAR;CYLINDIRICAL;SPHERICAL;
JOINTED-ARM(VERTICAL);JOINED-ARM(HORIZONTAL).
 DEGREES OF FREEDOM: ROBOT ARM; ROBOT WRIST.
 POWER SOURCES: ELECTRICAL;PNEUMATIC;HYDRAULIC;ANY
COMBINATION.
 TYPE OF MOTION: SLEW MOTION; JOINT-INTERPOLATION;
STRAIGHT-LINE INTERPOLATION; CIRCULAR INTERPOLATION.
 PATH
CONTROL: LIMITED SEQUENCE; POINT-TO-POINT;
CONTINOUS PATH; CONTROLLED PATH.
 INTELLLIGENCE
LEVEL: LOW-TECHNOLOGY(NONSERVO);
HIGH-TECHONOLOGY(SERVO).
ARM GEOMETRY
ROBOT MUST BE ABLE TO REACH A POINT IN SPACE WITHIN THREE
AXES BY MOVING FORWARD AND BACKWARD, TO THE LEFT AND
RIGHT, AND UP AND DOWN.
ROBOT MANIPULATOR MAY BE CLASSIFIED ACCORDING TO THE TYPE
OF MOVEMENT NEEDED TO COMPLETE THE TASK.
RECTANGULAR-COORDINATED:
- HAS THREE LINEAR AXES OF MOTION.
- X REPRESENTSD LEFT AND RIGHT MOTION
- Y DESCRIBES FORWARD AND BACKWARD MOTION.
- Z IS USED TO DEPICT UP-AND-DOWN MOTION.
THE WORK ENVELOPE OF A RECTANGULAR ROBOT IS A CUBE OR
RECTANGLE, SO THAT ANY WORK PERFORMED BY ROBOT MUST ONLY
INVOLVE MOTIONS INSIDE THE SPACE.
RECTANGULAR CO ORDINATES:ADVANTAGES:
 THEY
CAN
OBTAIN
LARGE
WORK
ENVELOPE
BECAUSE
RAVELLING ALONG THE X-AXIS, THE VOLUME REGION CAN BE
INCREASED EASILY.
 THEIR LINEAR MOVEMENT ALLOWS FOR SIMPLER CONTROLS.
 THEY
HAVE
HIGH
DEGREE
OF
MECHANICAL
RIGIDITY,
ACCURACY, AND REPEATABILITY DUE O THEIR STRUCTURE.
 THEY CAN CARRY HEAVY LOADS BECAUSE THE WEIGHTLIFTING CAPACITY DOES NOT VARY AT DIFFERENT LOCATIONS
WITHING THE WORK ENVELOPE.
 DISADVANTAGES:-
 THEY MAKES MAINTENANCE MORE DIFFICULT FOR SOME
MODELS WITH OVERHEAD DRIVE MECHANISMS AND CONTROL
EQUIPMENT.
 ACCESS TO THE VOLUME REGION BY OVERHEAD CRANE OR
OTHER MATERIAL-HANDLING EQUIPMENT MAY BE IMPAIRED BY
THE ROBOT-SUPPORTING STRUCTURE.
 THEIR MOVEMENT IS LIMITED TO ONE DIRECTION AT A TIME
APPLICATION:
 PICK-AND-PLACE OPERATIONS.
 ADHESIVE APPLICATIONS(MOSTLY LONG AND STRAIGHT).
 ADVANCED MUNITION HANDLING.
 ASSEMBLY AND SUBASSEMBLY(MOSTLY STRAINGHT).
 AUTOMATED LOADING CNC LATHE AND MILLING OPERATIONS.
 NUCLEAR MATERIAL HANDLING.
 WELDING.
CYLINDRICAL-COORDINATED
HAS TWO LINEAR MOTIONS AND ONE ROTARY MOTION.
ROBOTS CAN ACHIEVE VARIABLE MOTION.
THE FIRST COORDINATE DESCRIBE THE ANGLE THETA OF BASE
ROTATION--- ABOUT THE UP-DOWN AXIS.
THE SECOND COORDINATE CORRESPOND TO A RADICAL OR Y--- IN
OUT MOTION AT WHATEVER ANGLE THE ROBOT IS POSITIONED.
THE FINAL COORDINATE AGAIN CORRESPONDS TO THE UP-DOWN Z
POSITION.
CYLINDRICAL-COORDINATED
ROTATIONAL ABILITY GIVES THE ADVANTAGE OF MOVING RAPIDLY
TO THE POINT IN Z PLANE OF ROTATION.
RESULTS IN A LARGER WORK ENVELOPE THAN A RECTANGULAR
ROBOT MANIPULATOR.
SUITED FOR PICK-AND-PLACE OPERATIONS.
 ADVANTAGE:
 THEIR VERTICAL STRUCTURE CONSERVES FLOOR SPACE.
 THEIR
DEEP
HORIZONTAL
REACH
IS
USEFUL
FOR
FAR-
REACHING OPERATIONS.
 THEIR CAPACITY IS CAPABLE OF CARRYING LARGE PAYLOADS.
DISADVANTAGE:
 THEIR OVERALL MECHANICAL RIGIDITY IS LOWER THAN THAT
OF THE RECTILINEAR ROBOTS BECAUSE THEIR ROTARY AXIS
MUST OVERCOME INERTIA.
 THEIR REPEATABILITY AND ACCURACY ARE ALSO LOWER IN
THE DIRECTION OF ROTARY MOTION.
THEIR CONFIGURATION REQUIRES A MORE SOPHISTICATED CONTROL
SYSTEM THAN THE RECTANGULAR ROBOTS
APPLICATION:
 ASSEMBLY
 COATING APPLICATIONS.
 CONVEYOR PALLET TRANSFER.
 DIE CASTING.
 FOUNDARY AND FORGING APPLICATIONS.
 INSPECTION MOULDING.
 INVESTMENT CASTING.
 MACHINE LOADING AND UNLOADING.
SPHERICAL COORDINATED
HAS ONE LINEAR MOTION AND TWO ROTARY MOTIONS.
THE WORK VOLUME IS LIKE A SECTION OF SPHERE.
THE FIRST MOTION CORRESPONDS TO A BASE ROTATION ABOUT A
VERTICAL AXIS.
THE SECOND MOTION CORRESPONDS TO AN ELBOW ROTATION.
THE THIRD MOTION CORRESPONDS TO A RADIAL, OR IN-OUT,
TRANSLATION.
A SPHERICAL-COORDINATED ROBOTS PROVIDES A LARGER WORK
ENVELOPE THAN THE RECTILINEAR OR CYLINDIRICAL ROBOT.
DESIGN GIVES WEIGHT LIFTING CAPABILITIES.
ADVANTAGES
AND
DISADVANTAGES
SAME
AS
CYLINDIRICAL-
COORDINATED DESIGN.
APPLICATIONS:
 DIE CASTING
 DIP COATING
 FORGING
 GLASS HANDLING
 HEAT TREATING
 INJECTION MOLDING
 MACHINE TOOL HANDLING
 MATERIAL TRANSFER
 PARTS CLEANING
 PRESS LOADING
2)Explain sensors involve in robotic system?
Sensors
Sensors are the perceptual system of a robot and measure physical quantities like
contact, distance, light, sound, strain, rotation, magnetism, smell, temperature,
inclination, pressure, or altitude. Sensors provide the raw information or signals
that must be processed through the robot's computer brain to provide meaningful
information. Robots are equipped with sensors so they can have an understanding
of their surrounding environment and make changes in their behavior based on the
information they have gathered.
Sensors can permit a robot to have an adequate field of view, a range of detection
and the ability to detect objects while operating in real or near-real time within
it's power and size limits. Additionally, a robot might have an acoustic sensor to
detect sound, motion or location, infrared sensors to detect heat sources, contact
sensors, tactile sensors to give a sense of touch, or optical/vision sensors. For
most any environmental situation, a robot can be equipped with an appropriate
sensor. A robot can also monitor itself with sensors.
The Big Signal robot NOMAD uses sensing instruments like a
camera, a spectrometer and a metal-detector. The high
resolution video camera can identify dark objects (rocks,
meterorites) against the white background of the Antarctic
snow. The variations in color and shade allow the robot to tell
the difference between dark grey rocks and shadows. Nomad uses a laser range
finder to measure the distance to objects and a metal detector to help determine
the composition of the objects if finds.
Very complex robots like Cassini have full sets of sensing equipment much like
human senses. It's skeleton must be light and sturdy, able to withstand extreme
temperatures and monitor those temperatures. Cassini determines it's location by
using three hemisperical resonant gyroscopes or HRG's which measures quartz
crystal vibrations. The eyes of Cassini are the Imaging Science Subsystem (ISS)
which can take pictures in the visible range, the near-ultraviolet and near-infrared
ranges of the electromagnetic spectrum.
3) Briefly explain microprocessor based speed control of DC motor?
Here the DC motor is controlled by the microprocessor (8085). The kit used
was dynalog 8085 kit.The DC motor is very difficult to control unlike the stepper motor,
which can be controlled by giving the appropriate CONTROL WORD.By knowing the DC
motor theory we know the different methods used to control the motor, the most primitive
and the once upon a time the most popularly method was WARDLEONARD motor speed
control, but this had many disadvantage, so the world of Electronics brought in thethyristor
control, which were very flexible and can be employed to use AC instead of DC cause they had a
inbuilt convertor. The thyristor-based system is good but when used with Microprocessor based
speed controller they are really good. We have shown the block diagram, circuit diagram used by
us to control a small tape recorder sized motor.
SPEED CONTROL:The microprocessor takes a feedback from the ‘CONTACTLESS INFRARED LED
SPEED MEASUREMENT’ designed and developed by us. It is similar to a rotary
encoder we used only one wooden rigid disc with a hole (even at center for mounting
purpose). Then using a sensor (Infrared) like those readily available in the market (we
have shown it in diagram) or a common infra LED pair mounted and aligned properly to
sense each other. When the DISC rotate the counter starts counting but it increment only
when the LED come in sight of each other which is possible when the hole portion of the
disc comes in turn we can find the speed of the rotation by proper calibration .The main
task of counting, calibrating, calculating, comparing is incorporated in the software used
the 8085 system (EPROM).So by comparing the speed reading with the wanted/predetermined
speed we can adjust the threshold controlling the DC motor power supply and hence in turn
control the DC motor.
Safety:It’s important to isolate the power supply region, the controlling section and the
digital microprocessor hardware section. To isolate the digital system we can use
IC’s like MCT2E, or to control directly MC series has another IC, which
incorporates a TRIAC directly! So easy to control higher power rating/Voltage
motor. It’s always better to useseparate PCB for each .The EPROM should be
isolated as possible from the power electronics appliances!