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PROGRAMMABLE LOGIC
CONTROLLER
DNT 353/3
BY:
Salsabila Ahmad
CHAPTER 1
ELECTRICAL CONTROLLER
EQUIPMENT
BY:
Salsabila Ahmad
ELECTRICAL CIRCUIT BASIC
4 ELECTRICAL BASICS
• POWER SUPPLY
• INPUT DEVICE
– Input Controller Equipment
• CONDUCTOR
• OUTPUT DEVICE
– Output Controller
Equipment
POWER SUPPLY
Definition:
A device which supplies
energy needed to create an
electrical current
EXAMPLES OF POWER
SUPPLY
• Battery
• DC Power Supply
• AC Power Supply
INPUT
DEVICE
• DEFINITION
• 2 TYPES OF INPUT DEVICE
– Mechanical input device
– Solid state proximity device
• ELECTRICAL SWITCHING
– Basic Principle of Electrical
Switching
– Types of Contacts
– How do These Contacts Work?
DEFINITION:
• A device which allows/ controls
the flow of current in a circuit
• These devices are known as
“ELECTRICAL CONTROLLER
EQUIPMENTS”
• Provides Electrical Switching
MECHANICAL INPUT
DEVICES
Definition:
• An input device with a mechanical
contact
EXAMPLE OF MECHANICAL
INPUT DEVICES
•
•
•
•
•
•
•
•
•
Contact Relay
Push button
Limit Switch
Selector Switch
Toggle Switch
Temperature Switch
Pressure Switch
Solenoid Switch
Induction Motor Controller
CONTACT
RELAY
• Relay Coil
– output device
But
• Relay Contact
– input device
RELAY
2 TYPES OF RELAY:
• EMR
• SSR
CHARACTERISTICS OF EMR & SSR
RELAY SYMBOLS
ELECTROMAGNETIC
RELAY (EMR)
Definition:
• An EMR is an electromagnetic
device composed of a frame/core,
electromagnet coil and contacts
(move and fixed)
• Based on simple electromagnetic
principle
SOLID STATE RELAY
(SSR)
HOW IT OPERATES?
• Operates similarly to EMR, but with no
mechanical contact.
• Employ semiconductor switching
elements
– thryristors
– triacs
– diodes
– transistors.
• Employ optical semiconductors
called photo couplers to isolate
input and output signals.
• Photo couplers change electrical
to optical signals and relay the
signal through space.
CHARACTERISTICS OF
EMR AND SSR
EMR
•slow speed
•wears out easily
•noisy
•cheap
SSR
•high speed, high
frequency for switching
operations
•no failure due to wear
out, since no
mechanical contacts
•little noise
•expensive
RELAY SYMBOLS
• Commonly used in
electrical machine
diagram
Normally
open
(NO)
Normally
close
(NC)
Coil
BASIC PRINCIPLE OF
ELECTRICAL SWITCHING
• A situation of breaking and open an
electrical circuit
• Or to direct current from one
conductor to another.
• The PLC is the solution to today’s
electrical switching requirements
– where it is able to solve complex
switching requirements.
2 TYPES OF CONTACT
NO
NC
HOW DO THESE CONTACTS
WORK?
• Once coil is energized, the contact will
change state
– NO  NC
– NC  NO
PUSH BUTTON
•
•
•
•
Definition
Concepts of Operation
Application of Push Button
Schematic Symbols
DEFINITION
• pushbutton-type operator
• Have one set or more contact/spring
• Mostly have a set of normally open (NO)
and normally closed (NC) contact
CONCEPTS OF OPERATION
• Pushing the operator causes the contacts to change
state
• Spring causes switch operator to automatically return to
it’s natural state when it is released.
NO
NC
natural state


NC
NO
change state


NO
NC
automatic return
• a switch with this return spring action, is called a
momentary switch.
APPLICATIONS
• Frequently used in
industrial
applications to
control functions
such as
– starting
– and stopping
the machine’s
operation
• With a safety
nature. Why?
SCHEMATIC SYMBOLS FOR
PUSH BUTTON
Normally Open Contact
Normally Closed Contact
LIMIT SWITCH
SELECTOR SWITCH
• Definition
• Application
• Schematic Symbols
DEFINITION
• Similarly to pushbutton, but instead
of pushing, you rotate a knob
• may be designed to stay in a
selected position or may have a
momentary action
• selector switch that stays in a
certain position is called a
maintained switch.
APPLICATION
• Widely used in industrial applications
– for switching mode of operation
• For example from automatic to manual
modes
– to turn the main power on and off
– to select between AC or DC output.
• Some requires key (authorized person) to turn
on for safety reason.
SCHEMATIC SYMBOLS FOR
SELECTOR SWITCH
Normally
open contact
Normally
close contact
Selector switch with two contacts
TOGGLE SWITCH
Toggle switch is a maintained switch
What is a maintained switch?
TEMPERATURE SWITCH
PRESSURE SWITCH
SOLENOID SWITCH
• Use concept of magnetic flux for
armature/plunger to move
• Produces linear mechanical motion
INDUCTION MOTOR
CONTROLLER
• Commonly used micro-controllers
PROXIMITY
SENSORS
SOLID STATE PROXIMITY
DEVICES
Definition:
• An electronic input device which
needs power to be able to operate
Proximity Sensors Category
PROXIMITY
SENSORS
CATEGORY
Proximity sensors
inductive
capacitive
dielectric type
conductive type
ultrasonic
optical
diffuse reflective type
retro reflective type
thru beam
fiber optic sensor
color mark sensor
encoder sensor
INDUCTIVE PROXIMITY
SENSOR
• Sense only metallic objects
– e.g. steel, iron, aluminum, tin, copper
etc
• Has limited sensing range
– range affected by the type of metal
sense
An oscillator and a detection coil generate a magnetic field that produces Eddy
currents in a nearby metallic object (the detectable object). These Eddy
currents generate a magnetic field that influences the field produced by the
sensor’s detection coil.
CAPACITIVE
PROXIMITY SENSOR
• sense all material with mass.
• operation for both dielectric
and conductive type are the
same
CAPACITIVE PROXIMITY
SENSOR
• The dielectric type works best for high
density material
– Low density material (e.g. paper,
foam etc) do not cause a detectable
change in dielectric.
• The conductive type works best on
electrically conductive material
– e.g. metal or water-based material)
ULTRASONIC SENSOR
• Use ultrasonic technology
• How does it works?
CONCEPTS OF ULTRASONIC
SENSOR
• Use an ultrasonic “ping” sent from
sensor to target
– Sensing area is a funnel shape area
– Therefore, target must be located directly
in front of sensor
• When echo is returned, sensor detects
target by measuring time delay
between transmitted ping and returned
echo
– sensor calculate distance between
sensor and target
CONCEPTS OF ULTRASONIC
SENSOR (cont’)
• Do not work well on cloth, foam
rubber
– since good absorber of sound waves
• Works best on high density
material
– where sound waves reflects best
DIFFUSE REFLECTIVE
• Emitter and receiver
located in same
housing
DIFFUSE REFLECTIVE
Emitter
and receiver
• Light emitted is received when the
object is present
• Works well on glossy target but not
transparent
RETRO-REFLECTIVE
• Emitter and receiver located in
same housing.
RETRO-REFLECTIVE
Emitter
and receiver
reflector
•
•
Light emitted is received when the
object is absent.
Does not work well with glossy
target. Why?
–
Because glossy target acts like a
reflector
EXERCISE:
If you have a shinny
object as a target, which
type of sensor do you
choose; retro or diffuse?
THRU-BEAM
• Emitter and receiver is located in
different housing
THRU-BEAM
emitter
receiver
• Sense the object’s present when
it passes through between
emitter and receiver
–
where it stops the light from hitting
receiver
FIBER OPTIC
• Available in
both thru beam
and reflective
FIBER OPTIC
Thru-beam
object
Reflector
• Use plastic and glass fibers to
carry lights
COLOR MARK
• A special type of diffuse reflective
optical sensor that can
– differentiate between colors
• some can detect contrast between
colors.
• Typically used to check labels and
sort packages by color mark.
ENCODER
• Used for position feedback and
some for velocity feedback
• Two main types
– Incremental
– absolute
CONDUCTOR
CONDUCTOR
Definition:
• A medium that connects all the
components and allows current to
flow.
Examples:
• copper wire
• bread board
• What else???
OUTPUT
DEVICE
• Definition
• Example
DEFINITION
• A component that will produce a
desired output. E.g.
– Sound
– Light
– Movement etc
• It is also referred to as a load.
EXAMPLE
•
•
•
•
•
•
•
Coil
Buzzer/Alarm
Lamp
Motor
Solenoid
Timer
Counter
COIL
Can represents various forms of
output including
• Motor
• Light
• Pump
• Counter
• Timer
• Relay
BUZZER
LAMP
MOTOR
• Types of Motor
• In PLC, motor can only be
controlled for
– power (ON/OFF)
– direction (CCW/CW)
– preset speed
TYPES OF MOTOR
DC motor type
wound field
permanent magnet
electronics commutation
dc motors
AC motor type
induction motors
synchronous motor
SOLENOID VALVE
TIMER
Function:
• Used to delay actions
Common symbols
Timer Characteristics
How they are
differentiate?
How they are
programmed?
DEFINITION
• Used to provide time delay.
COMMON SYMBOLS OF
TMR
TIMER
INPUT
TIMER0
• most common symbol for
displaying timer function is in
block diagram
T0
K40
– uses a box shape to display the timer
function
– Sometimes, timer is displayed in coil
format symbol
CHARACTERISTICS OF
TIMER
• Timers typically have one or two input
• Timer with one input has functions as a
timer enable input. When input ‘high’,
the timer begins timing
• A timer with 2 inputs has additional
functions which is used to reset the
timer accumulated time to zero when
the second input is ‘high’
• Every timer has a time base
– Typically; 1 sec, 0.1 sec and 0.01sec.
HOW TIMERS ARE
IDENTIFIED?
• Each timer will have number to
identify it
• There are two parameters for
timer
– timer number
• Used to identify timer e.g. Timer 0,
Timer 2.
– Preset value
• Is the delay time set for the timer
TIMER’S PROGRAM
• There are still many similarities in the
way the timers are programmed
– even when PLC are different brand
• Let say the time base of a timer is 0.1
second
– Therefore, if a programmer entered 50 for
the number of delay increments
– What is the timer’s delay?
• the timer would have a 5-second delay.
• 50 x 0.1 sec = 5 sec
COUNTER
• What is it?
• What is its characteristics?
DEFINITION
•
used to capture and store number of
occurrence
• Common applications of counters
– include keeping track of the number
of items moving past a given point
– determining the number of times a
given action occurs
CHARACTERISTICS
• set to some preset number value
– when this value of input pulses has been
received, it will operate its contacts
• Let say the counter is set for 10
pulses, then when 10 pulse impulses
have been received, the counter
contacts will close
• When there is a input transition for X0
from OFF to ON, counter starts
counting
• When the RESET is ON, the counter
resets to 0