2. STUDENTS LEARNING OUTCOME
At the end of the lesson, students will be able
to define industrial automation system.
to explain fixed/hardwired automation.
to explain programmable automation.
to compare fixed/hardwired automation to
programmable automation from the points of
flexibility, economy, space needed and ease of
maintenance.
5. Industrial automation systems
Automation systems used in industrial such
as robotic arm, electro-pneumatic system and
others to increase product
quality, productivity, reduce production cost
and reduce intervention of human in the
process of production.
8. Fixed /hardwired automation
● In fixed/hardwired automation, the control
logic functions are determined by the way
devices are electrically interconnected.
● Hardwired logic can be implemented using
relays and relay ladder schematics
● Hardwired control logic also can be
implemented by using logic gate.
9.
10. Logic gate implementation have the
advantages over relay logic in term of space
utilisation, less wiring requirement and more
economical.
Implementation using gate
11. Programmable automation
In Programmable automation, the control function of the system is
determined by software implemented through embedded system,
computer or PLC ( programmable Logic Control )
Replace by software
12. Comparison between hardwired and
programmable automation system
Hardwired automation
• Too many wiring work in the Panel
• Difficult to modify and make changes
• Difficulty in troubleshooting
• Due to difficulty in troubleshooting and drawing update,
machine down time is longer
• High power consumption as many relays are used
13. Comparison between hardwired and
programmable automation system
Programmable automation
• Wiring of the system usually reduces by 80% compared to hardwired control
system
• Power consumption is greatly reduced.
• Self diagnostic function enable easy and fast troubleshooting of the system
• Flexible. Control sequence can be changed by reprogramming.
• Faster response time
• More robust and reliable because less moving part
• Modular design- easy to repair and expand.
• Less expensive
• Hardcopy of documentation can be easily printed out and maintained.
15. STUDENTS LEARNING OUTCOME
At the end of the lesson, students will be able
To draw symbol and structure, to explain the operation and
application of relay.
To draw symbol and structure, to explain the operation and
application of contactor.
To draw symbol and structure, to explain the operation and
application of timer.
To draw symbol and structure, to explain the operation and
application of counter.
16. Although PLC has replaced much of the relay
control logic, electromagnetic relays are still used as
auxiliary devices to switch I/O field devices
RELAY
18. • An electrical relay is a magnetic switch. It uses
electromagnetism to switch contacts.
• A relay will usually have only one coil but may have any
number of different contacts.
• The contact can be single pole single throw (SPST), single
pole double throw (SPDT) double pole single throw (DPST)
, double poles double throw (DPDT) or more than 2 poles
double throw.
19. Operation
• With no current flow through the coil (de-
energized), the armature is held away from
the core of the coil by spring tension.
• When the coil is energized, it produces an
electromagnetic field. Action of this field, in
turn, causes the physical movement of the
armature.
• Movement of the armature causes the
contact points of the relay to open or close.
• The coil and contacts are insulated from
each other: therefore, under normal
conditions. no electric circuit will exist
between them
22. • Contactor works like a relay except that it can
handle a much higher current at its contacts.
• It is usually operated by AC voltage applied across
it magnetic coil.
• Other than the power circuit contacts for connecting
the controlled device such as motor to the 3 phase
lines, it also has auxiliary contacts ( consist of NC
and NO type )for building control circuit.
23. Controlling a high current pump by PLC
through a contactor
Since PLC output only capable of
handling low current, a contactor
is needed to interface the pump to
PLC
The output of PLC is connected in
series with the coil to form a low
current switching circuit.
The contacts of the contactor are
connected in series with the pump
motor to form a high-current
switching circuit.
24. Application
3 phase motor forward reverse control
Power circuit Control circuit
Forward: A1 , B2, C3
Reverse : A2, B1, C3
26. Application
OL heater coil
OL contact
heater coils are connected in series with
the motor winding
If the motor draws excessive current from the
main, temperature on the heater raises and triggers the
OL relay
The contact of the OL relay then cuts off
the supply to the contactor coils in the
control circuit.
the contactors de-energize and
disconnects the motor from the main
supply
27. Application
When forward button is
pushed
Contactor M1 is
energized
When forward button is
release
Contactor M1 is
latched through
its’ own contact
M1.
Power contacts of M1
close, connect A,B,C to
1,2,3 respectively This contact opens to present motor
from changing to reverse mode when
reverse button is pressed. This
precaution is called interlock
Motor can be stopped by
pressing this stop button
When reverse button is pushed
and released
Contactor M2 is
latched through
its’ own contact
M2.
28. Application
Power contacts of M2
close, connect A,B,C to
2,1,3 respectively
This contact opens to present motor
from changing to forward mode when
forward button is pressed. This
precaution is called interlock
31. Introduction
• A timer can provide a delay in time operation.
• Usually the duration of delay can be adjusted by changing
the dial setting.
• The most commonly used timer are the on delay timer and
off delay timer
• An on delay timer’s contact would not operate
until a preset delay time has elapsed after it is
energized,
• An off delay timer’s contacts will immediately
operate and stay in this active state once it is
energized
• But its’ contacts will only deactivate after a preset
time has elapsed once it is de-energized.
32. Motor driven cam timer
In most industrial and factory
applications, electromechanical timers are driven
by a synchronous motor that turns the cam through
the switch contacts.
33. Application example
Star-delta motor starter
• Induction motor when started from stall , draw high current
from supply. cause disturbance to main supply
• Once move at rated speed, current reduces to normal; very
much smaller than the starting current.
• To avoid this situation,
– apply lower voltage during start
– Apply normal voltage after motor run steadily – after a few
second
• One method of doing it is by using star connection at start and
switch to delta connection for the motor winding after a few
seconds
44. Counter application
Counting object on conveyor belt .
counter
sensor
Sensor sends electrical pulse to counter every
time it detects an object.
45. QUIZ 1 : 1.0 Introduction to Automation System (10 MARKS)
S1a What is hard wired automation in control
system ?
b. What is the main component used in this
system ?
c. What does NO contact mean in Relay?
d. Name TWO types of Relay contact.
e. The operation of Relay and Contactor are
similar, what is the difference in usage between
them?
