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REFERENCE NO: E42 - ELECTRO 2
1. COURSE NAME: Electro Technology 2
2. COURSE DESCRIPTIONS: The course includes the Cables, Alternating
Current, Alternators, D.C. Generators, Maintenance of Generator
and Circuit Breakers, A.C. Motors, D.C. Motors, Maintenance of
Motors and Starters, Fault Protection and Fault Location.
3. NUMBER OF UNITS FOR LECTURE AND LABORATORY:
3 LECTURE, 1 LABORATORY = 4 UNITS
4. NUMBER OF CONTACT HOURS PER WEEK:
3 LECTURE, 1 LABORATORY = 6 HOURS.
5. PREREQUISITE: Electro Technology 1
6. COURSE OBJECTIVES: The students shall be able to process adequate
theoretical knowledge and practical skill to carry out the duties of an
engineer of a watch in safe and efficient manner.
FUNCTION: F2 - Electrical and Electronic and Control Engineering at the
operational level (Operate Alternators, Generators and Control
Systems)
7. COURSE OUTLINE:
LEARNING OBJECTIVES/OUTCOMES:
The students shall be able to . . . . . .
7.1. Cables
7.1.1 name materials commonly used for the following parts of cables:
7.1.1.1 conductors
7.1.1.2 insulation
7.1.1.3 sheathing
7.1.2 describe the reaction of electric cables to a fire
7.1.3 Fit cable through glands into a terminal box, earthing the
armouning as appropriate
7.1.4 Soldier and crimps terminal sockets to conductors
7.1.5 Explain why cables sockets need be securely attached and
locked on to the terminal
7.1.6 Measure resistance of cable
7.1.7 Explain the limitation of temporary repairs to insulation
7.1.8 Carries out temporary repairs to insulation
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7.2. Alternating Current
7.2.1 Develop the expression e = Blv to produce e = Emax sin 0,where
e is the instantaneous voltage,Emax is the maximum voltage
and 0 is the displaced angle
7.2.2 Project the vertical components of a rotating vector to draw one
complete cycle of a sine wave
7.2.3 States that the rotating vector is called a phasor
7.2.4 Using a triangle produced from the above objective, confirms
that e= sin 0
7.2.5 Superinpose degrees and radians on the sine wave drawn in
the above
7.2.5.1 Rotation
7.2.5.2 angular velocity
7.2.5.3 periodic time
7.2.5.4 frequency
7.2.5.5 peak value
7.2.5.6 amplitude
7.2.6 Deduce the expression e = Emax sin 2ft
7.2.7 Calculate instantaneous voltages, given the unknown qualities
7.2.8 Explain what is meant by phase difference between voltage
and current values
7.2.9 Sketch two sine waves of the same frequency but having
different amplitudes and a phase different, indicating the phase
difference
7.2.10 Explain why not root mean square ( r.m.s ) values are used
7.2.11 Given a series of value of instantaneous voltage or current for
a half cycle, calculates r.m.s. value
7.2.12 State that the r.m.s. value for sine wave is 0.707 of the peak
value
7.3. Alternators
7.3.1 State that the a. c. voltages normally given are root mean
square values and that all equipment is rated in these terms
7.3.2 State that peak values are 2 times larger than r.m.s. values
7.3.3 State that, for a given generator:
7.3.3.1 Frequency is dictated by the speed of rotation
7.3.3.2
E.m.f. is controlled by the size of the magnetic flux
(excitation)
7.3.4
Describe in simple terms an a. c. generator with three-phase
winding, stating the phase different
7.3.4.1 Sketch
a schematic arrangement of three-phase
alternator with star connection
7.3.4.2 In the terminal box of a stator field winding, identifies
the outlets of the three phases and the common neutral
connection
7.3.4.3 Sketch a part section of a salient pole generator,
showing the field windings and the armature conductors
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7.3.5
7.3.6
7.3.7
7.3.8
7.3.9
7.3.10
7.3.11
7.3.12
7.3.13
7.3.14
7.3.15
7.3.16
7.3.17
7.3.18
7.3.19
7.3.20
7.3.21
7.4.
Explain how excitation of the rotor is produced and supplied
Describe how generator is cooled
List the parts of a generator fitted to a generator
Explain why the function of an automatic voltage regulator
Sketch a block diagram of an automatic voltage regulator,
naming the main components and explaining the purpose of
the hand trimmer
Explain such sources of supply can be run in parallel and
those which cannot
Perform or describes the synchronizing sequence to bring a
generators into service in parallel with running generator, using
both a synchroscope and lamps
Adjust, or describes how to adjust, the load sharing of two
generator running in parallel
Either performs the procedure, or describes how, to reduce the
load on a generator and takes it out of service
State that load sharing can be automatically controlled
State that the construction and operation of an emergency
generator is similar to that of a main generator
State the usual voltage, frequency and number of phases of an
emergency generator
State that the emergency feeds its own switchboard and that
both are usually installed in the same compartment above the
waterline
describe the connections between the emergency and main
switchboards and the necessary safeguards
describe the situation where the emergency generator would
be started up automatically and the methods of starting
Describe the regular “ no load “ running and the occasional “on
load “ running of the emergency generator
Perform routine maintenance and testing of an alternator
D.C. Generators
7.4.1 Sketch, in diagrammatic form, the basic circuit for a d.c.
generator
7.4.2 On a given drawing or an actual generator, identifies the field
pokes, yoke, shoe, field winding and interpoles
7.4.3 Describe the differences in appearance of shunt coils and
series coils
7.4.4 On a given drawing or an actual generator, identify the
windings, commutator, commutator insulation, laminations,
clamping arrangement, ventilation holes, coil-retaining
arrangements, brushes, tails, brush loading arrangement and
bearings
7.4.5 Name two of types of winding used on armatures
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7.5. Maintenance of Generator and Circuit Breakers
7.5.1 State the safety and isolation precautions necessary before
commencing work
7.5.2 List the parts to be inspected, their common faults and the
necessary remedial action
7.5.3 Check and adjusts pressures on carbon brushes
7.5.4 Replace and beds in a new carbon brushes
7.5.5 Tests and records values of insulation resistance
7.5.6 Describe or carries out a maintenance routine on main circuit
breakers
7.5.7 Describe briefly the principle of the various types of closing
mechanism of circuit breakers
7.5.8 Describe the care to be taken when handling circuit breakers
7.5.9 List the ways in which a circuit breaker can be tripped
7.5.10 Explain the purpose of interlocks fitted to circuit breakers
7.5.11 Detect and corrects faults implanted in circuit breakers
7.6. A.C. Motors
7.6.1 State the normal supply for three-phase induction motors
7.6.2 name the types of motor commonly used on board ship,
giving their applications
7.6.3 Given the actual component from a three-phase induction
motor, identifies:
7.6.3.1 Rotor
7.6.3.2 Bearings
7.6.3.3 Fan
7.6.3.4 Starter
7.6.3.5 field windings
7.6.3.6 rotor cage
7.6.3.7 method of ludrication
7.6.3.8 terminals
7.6.4 Explain the differences between the following motor
enclosure, describing how cooling is achieved in each case:
7.6.4.1 drip-proof
7.6.4.2 totally enclosed
7.6.4.3 deck watertigh
7.6.4.4 flameproof
7.6.5 Sketch a graph showing the relationship between speed and
local and between current and load, from no load to full load
7.6.6 Given a motor name plate, explains the meaning of all the
information displayed
7.6.7 Explain in terms how the driving torque is produced in an
induction motor
7.6.8 Explain why slip is essential
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7.6.9
Describe the variation of current when direct starting an
induction motor and its effect on the motors windings and on
other electrical equipment
7.6.10 State which motor might have a means of reduced-voltage
starting
7.6.11 Sketch a schematic arrangement of a direct on-line starter,
naming the main parts and explaining their function
7.6.12 Explain the reason for starting up a motor with its stator
winding star-connected
7.6.13 Given a labelled circuit diagram for an automatic star-delta
starter, describes the starting sequence
7.6.14 Explain the results if a motor is allowed to continue running in
its starting (star-connected) stage
7.6.15 State the starting is sometimes accomplished by using an
autotransformer
7.6.16 Describe the principle of an autotransformer starter
7.6.17 Explain the basic reason for the provision of motor protection
7.6.18 Explain the principle of the most common over current relays
7.6.19 Explain difference between the largest possible overload
current and a fault current
7.6.20 Describe the function of the overcurrent trip, time delays and
fuses with both overload and fault currents
7.6.21 Explain the basis upon which fuses are chosen
7.6.22 Explain the principle of thermal relay, including the means of
its adjustment
7.6.23 Explains what meant by single phasing and its effect on a
motor:
7.6.23.1 when running
7.6.23.2 when starting
7.6.23.3 if continued attempts to start are made
7.6.24 describe in principle the protection against running with a
phase open-circuited
7.6.25 Explain why undervoltage trips are necessary
7.6.26 State applications where the following speeds are suitable:
7.6.26.1 single fixed speed
7.6.26.2 two or three fixed speeds
7.6.26.3 infinitely variable speed
7.6.27 describe briefly how stepped speed can be provided
7.6.28 List the means of producing variable speed
7.6.29 Describe the principle of the Ward-Leonard drive
7.6.30 Explain the principle of a variable-frequency motor
7.7. D.C. Motors
7.7.1
Explain what is meant by the back e.m.f. (Eb) of a motor
7.7.2
Relate the supply voltage to the back and to the voltage drop
in the armature (V=Eb+IaRa)
7.7.3
Explain why the starting current is high compared to the load
current
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7.7.4
7.7.5
Explain why a starter is required and the principle involved
States that rotational speed (N) is approximately proportional
to:
applied voltage or N α V
field flux
Ф
7.7.6
from the above objective, explains how the rotational speed
is affected by:
7.7.6.1 varying the voltage
7.7.6.2 varying the strength of the magnetic field
7.7.7
describe typical applications of:
7.7.7.1 shunt motors
7.7.7.2 series motors
7.7.8
In compound motors, explains what is meant by:
7.7.8.1 long shunt
7.7.8.2 short shunt
7.7.9
cumulatively connected
7.8. Maintenance of Motors and Starters
7.8.1
List the maintenance equipment for motors
7.8.2
Carries out the maintenance necessary for a cage electric
motor, paying particular attention to:
7.8.2.1 damp, condensation and air flow
7.8.2.2 dust and oil
7.8.2.3 external and internal surfaces
7.8.2.4 frequency of maintenance
7.8.2.5 deterioration of insulation
7.8.2.6 cleaning, inspection, renewal and lubrication of bearings
7.8.3
Describe the most common causes of failure of insulation
7.8.4
check the insulation resistance of at three-phase induction
motor
7.8.5
carry out the maintenance necessary, and completes reports
on, starters and controllers, with specific reference to:
7.8.5.1 casings, corrosion and bonding
7.8.5.2 contractors, magnet faces, pitting, overheating, spring
force, lubrication
7.8.5.3 connections, cables and leads
7.8.5.4 correct operation when in use
7.8.5.5 detect and rectifies faults implanted in motors, starter
and protection equipment
7.9. Fault Protection
7.9.1
explain why fault protection is essential
7.9.2
name the component parts of fault-protection equipment
7.9.3
explain why fault currents can be extremely high
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7.9.4
name the three types of over current-protection relay and
describes the principles of operation of each
7.9.5
explain the advantages and disadvantages of high-rupturingcapacity fuses
7.9.6
name the protection provided against:
7.9.6.1 short circuits
7.9.6.2 small overloads
7.9.7
describe the procedure when replacing a blown fuse
7.9.8
explain in simple terms, preferential tripping when
overloaded occurs
7.9.9
explain the purpose of under voltage protection of generators
and of motors
7.9.10 explain the purpose of reverse power protection
7.9.11 sketch the layout of a typical main switchboard, indicating
the function of the main parts
7.9.12 explain the danger associated with the spaces in the vicinity
of busbar
7.9.13 explain the use of transformers for switchboard instruments,
stating the voltages and current produced
7.9.14 describe the earthing of instruments
7.9.15 explain the potential danger of instrument voltage/current
transformer circuits and the safe procedure for working on
such circuits
7.9.16 explains how status indicator lamps are usually supplied with
power
7.9.17 describe the procedure if a fault develops with a miniature
circuit breaker describes the protection normally provided on
the doors of switchboard cubicles
7.9.18 adjusts, maintains and tests the types of fault protection
normally encountered
7.10. Fault Location
7.10.1 describe the essential requirements for the automatic
operation of marine machinery
7.10.2 use control and instrumentation terminology in its correct
context
7.10.3 compare pneumatic, hydraulic and electronic-electrical
control systems
7.10.4 describe a simple control loop\
7.10.5 name analogue and digital devices
7.10.6 locate faults in simple control systems
7.10.7 on locating fault takes actions to best prevent damage
8. EQUIPMENT, MATERIALS, CHEMICALS, TEACHING AIDS:
The equipment, materials, chemicals, teaching aids needed in
this course is listed in the attached APPENDIX 1
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9. REFERENCES:
9.1 STCW Code 1995, Table A - III/I
9.2 Reed, Thomas. “Advance Electro-Technology for
Engineers”.
9.3 Valkenburgh, Van. “Basic Electronics”.
9.4 Baria, Rogelio Jr., et.al. “Electro Technology 2”.
9.5 Kraal. “Basic Electro Technology for Engineers” 1994.
9.6 Fowler. “Fundamentals and Elements of Electricity”.
9.7 Zucker. “Electronics Measurement”.
9.8 Siskind. “Direct Current Machinery”.
E42-ELECTRO 2
Marine
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