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PROGRAMMABLE LOGIC CONTROLLER
(PLC) AND AUTOMATION
EJ501
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UNIT 5
PLC APPLICATION IN THE INDUSTRY
Objective :
Understand several practical examples of PLC application in the industry
• Develop and assemble conveyor motor control program.
• Determine and execute selection of material handling systems (part sorting).
• Determine and execute Package Control System.
• Develop and assemble Simple Traffic Light control program.
• Analyze and execute Loading and Unloading.
• Recognize other related examples
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UNIT 5
PLC APPLICATION IN THE INDUSTRY
Sample of how PLCs are being used in industry.
AUTOMOTIVE
Internal Combustion Engine Monitoring. A PLC acquires data recorded from sensors located at the internal
combustion engine. Measurements taken include water temperature, oil temperature, RPMs, torque, exhaust temperature, oil
pressure, manifold pressure, and timing.
Carburetor Production Testing. PLCs provide on-line analysis of automotive carburetors in a production assembly
line. The systems significantly reduce the test time, while providing greater yield and better quality carburetors. Pressure,
vacuum, and fuel and air flow are some of the variables tested.
Monitoring Automotive Production Machines. The system monitors total parts, rejected parts, parts produced,
machine cycle time, and machine efficiency. Statistical data is available to the operator anytime or after each shift.
Power Steering Valve Assembly and Testing. The PLC system controls a machine to ensure proper balance of the
valves and to maximize left and right turning ratios.
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UNIT 5
PLC APPLICATION IN THE INDUSTRY
CHEMICAL AND PETROCHEMICAL
Ammonia and Ethylene Processing. Programmable controllers monitor and control large compressors used during
ammonia and ethylene manufacturing. The PLC monitors bearing temperatures, operation of clearance pockets, compressor
speed, power consumption, vibration, discharge temperatures, pressure, and suction flow.
Dyes. PLCs monitor and control the dye processing used in the textile industry. They match and blend colors to
predetermined values.
Chemical Batching. The PLC controls the batching ratio of two or more materials in a continuous process. The system
determines the rate of discharge of each material and keeps inventory records. Several batch recipes can be logged and
retreived automatically or on command from the operator.
Fan Control. PLCs control fans based on levels of toxic gases in a chemical production environment. This system
effectively removes gases when a preset level of contamination is reached. The PLC controls the fan start/stop, cycling, and
speeds, so that safety levels are maintained while energy consumption is minimized.
Gas Transmission and Distribution. Programmable controllers monitor and regulate pressures and flows of gas
transmission and distribution systems. Data is gathered and measured in the field and transmitted to the PLC system.
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UNIT 5
PLC APPLICATION IN THE INDUSTRY
GLASS PROCESSING
Annealing Lehr Control. PLCs control the lehr used to remove the internal stress from glass products. The system
controls the operation by following the annealing temperature curve during the reheating, annealing, straining, and rapid
cooling processes through different heating and cooling zones. Improvements are made in the ratio of good glass to scrap,
reduction in labor cost, and energy utilization.
Glass Batching. PLCs control the batch weighing system according to stored glass formulas. The system also controls
the electromagnetic feeders for infeed to and outfeed from the weigh hoppers, manual shut-off gates, and other equipment.
Cullet Weighing. PLCs direct the cullet system by controlling the vibratory cullet feeder, weight-belt scale, and shuttle
conveyor. All sequences of operation and inventory of quantities weighed are kept by the PLC for future use.
Batch Transport. PLCs control the batch transport system, including reversible belt conveyors, transfer conveyors to the
cullet house, holding hoppers, shuttle conveyors, and magnetic separators. The controller takes action after the discharge
from the mixer and transfers the mixed batch to the furnace shuttle, where it is discharged to the full length of the
furnace feed hopper.
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UNIT 5
PLC APPLICATION IN THE INDUSTRY
MANUFACTURING/MACHINING
Production Machines. The PLC controls and monitors automatic production machines at high efficiency rates. It also monitors
piece-count production and machine status. Corrective action can be taken immediately if the PLC detects a failure.
Transfer Line Machines. PLCs monitor and control all transfer line machining station operations and the interlocking between
each station. The system receives inputs from the operator to check the operating conditions on the line-mounted controls and reports
any malfunctions. This arrangement provides greater machine efficiency, higher quality products, and lower scrap levels.
Wire Machine. The controller monitors the time and ON/OFF cycles of a wiredrawing machine. The system provides ramping
control and synchronization of electric motor drives. All cycles are recorded and reported on demand to obtain the machine's
efficiency as calculated by the PLC.
Paint Spraying. PLCs control the painting sequences in auto manufacturing. The operator or a host computer enters style and color
information and tracks the part through the conveyor until it reaches the spray booth. The controller decodes the part information and
then controls the spray guns to paint the part. The spray gun movement is optimized to conserve paint and increase part throughput.
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UNIT 5
PLC APPLICATION IN THE INDUSTRY
Conveyor Motor Control
Conveyor Control Using PLC :
1. Conveyor Belt
2. Infrared Sensor
3. Push Button Start (Normally
Open Contact)
4. Push Button Stop (Normally
Closed Contact)
5. Potentiometer Speed
Controller
6. Empty Lightbox
7. PLC (Programmable Logic
Controller)
8. Inverter for Speed Control
of Motor
9. Electric Motor
10. Belt and Pulley Systems
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UNIT 5
PLC APPLICATION IN THE INDUSTRY
Conveyor Motor Control
Sequence PLC Programming for Conveyor Control :
1. Conveyor Start
a. If Push Button Start = ON Then Output Unit for Start-Stop on Inverter = ON (Hold ON)
2. Conveyor Stop
a. If Push Button Stop = OFF Then Output Unit for Start-Stop on Inverter = OFF
b. If Infrared Sensor = ON Then Output Unit for Start-Stop on Inverter = OFF Else Output Unit for Start-Stop on
Inverter = ON
3. Empty Lightbox = ON
a. If Output Unit for Start-Stop on Inverter = ON AND Infrared Sensor = OFF AND Wait For 10 Seconds Then Empty
Lightbox = ON Else Empty Lightbox = OFF
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Input
Devices
Output
Devices
0000
Infrared Sensor
1000
Empty Lightbox
0001
Push Button Start
1001
Start-Stop on Inverter
0002
Push Button Stop
UNIT 5
PLC APPLICATION IN THE INDUSTRY
Conveyor Motor Control
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UNIT 5
PLC APPLICATION IN THE INDUSTRY
Conveyor Motor Control
Input
Device
Output
Device
00000
Sensor 1
(S1)
10000
Motor 1
(M1)
00001
Sensor 2
(S2)
10001
Motor 2
(M2)
00002
Sensor 3
(S3)
10002
Motor 3
(M3)
Operations:
10
• Motor 2 is ON when the sensor 3 detects
the objects.
• Motor 2 will be OFF when the motor 1 is
ON and the object was outside the range of
sensor 2.
•Motor 1 will be ON after sensor 2 detects
the objects.
• Motor 1 will be OFF when the object was
outside the range of sensor 1.
UNIT 5
PLC APPLICATION IN THE INDUSTRY
Conveyor Motor Control
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UNIT 5
PLC APPLICATION IN THE INDUSTRY
Part Sorting
Penderia Photoelectric 1 ( PH1 –
00002 ) berfungsi sebagai data
masukan pada shift register. Apabila
objek yang rosak dikesan oleh
pengesan, isyarat keluaran pada
sensor akan di ONkan.
Penderia Photoelectric 2 ( PH2 00003 ) digunakan sebagai penjana
masa yang berfungsi sebagai masa
masukan pada shift register. Satu
denyut akan dijanakan setiap masa
pada jarak yang ditetapkan pada
awalnya. Semasa produk yang rosak
dikesan oleh PH1, ia dikesan oleh
shift
register
sehingga
produk
tersebut tiba pada posisi yang
ditetapkan pada penghantar yang
akan dipicukan oleh injap magnetik (
MV – 10000 ).
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UNIT 5
PLC APPLICATION IN THE INDUSTRY
Part Sorting
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PLC APPLICATION IN THE INDUSTRY
Package Control System
Merujuk kepada rajah 9.3 dan jadual 9.3 , kotak yang berada di atas
penghantar akan bergerak apabila PB1 ditekan. Motor penghantar kotak
akan berhenti dan motor penghantar epal mula bergerak apabila kotak
tersebut di kesan. Penderia bahagian akan mengira sehingga 10 biji epal.
Selepas itu motor penghantar epal akan berhenti dan motor penghantar
kotak akan bergerak semula. Pembilang akan di set dan operasi akan
berulang semula sehingga PB2 ditekan.
Input
Device
00000
Push Button ( PB1 )
00001
Stop Button ( PB2 )
00002
Part Sensor ( SE1 )
00003
Box Sensor ( SE2 )
Output
14
Device
10000
Apple Conveyor
10001
Box Conveyor
UNIT 5
PLC APPLICATION IN THE INDUSTRY
Package Control System
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UNIT 5
PLC APPLICATION IN THE INDUSTRY
Simple Traffic Light
Input
Device
00000
Push Button ( PB1 )
00001
Stop Button ( PB2 )
Output
16
Device
10000
Traffic Light 1 (Green)
10001
Traffic Light 1 (Red)
10002
Traffic Light 2 (Green)
10003
Traffic Light 2 (Red)
UNIT 5
PLC APPLICATION IN THE INDUSTRY
Simple Traffic Light
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PLC APPLICATION IN THE INDUSTRY
Loading and Unloading
Input
Device
00000
Push Button ( PB1 )
00001
Stop Button ( PB2 )
00005
Upper Tank Limit (TLB1)
00006
Lower Tank Limit (TLB2)
Output
18
Device
10000
Input Motor Valve (MV1)
10001
Output Motor Valve (MV2)
10002
Motor (M)
10004
Level Indicator
10005
Buzzer
UNIT 5
PLC APPLICATION IN THE INDUSTRY
Loading and Unloading
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UNIT 5
PLC APPLICATION IN THE INDUSTRY
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