PROGRAMMABLE LOGIC

CONTROLLER (PLC)

AND AUTOMATION

1

EJ501

UNIT 2b

LOGICAL SENSORS AND ACTUATORS2

Objective

2. Logical Actuators

Describe solenoid, valves, cylinders and motors.

Explain solenoid, valves, cylinders and motors operations.

Use simple electro-hydraulics and electro-pneumatics systems usinglogical actuators based on simple logical control/automation.

UNIT 2b

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Solenoid

UNIT 2b

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Valves

UNIT 2b

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Cylinder

UNIT 2b

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Motor

UNIT 2b

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Hydraulic

UNIT 2b

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Electro -Hydraulic

The word electrohydraulic has two meanings for two highly different operations. It canstand for an electrical control device that makes precise adjustments in a hydraulicsystem. Also, it can mean a chemical reaction that is created by firing short, powerfulelectrical impulses into or directly beneath the surface of a body of liquid.

Perhaps the most well-known electrohydraulic device is an automobile's power steeringunit also called an electrohydraulic actuator. The unit combines high power with ahigh degree of accuracy to adjust for the minute movements of the steering wheel in avehicle. This type of technology, where electrical components are used to increase theaccuracy of hydraulic movements, can be applied to almost any situation wherehydraulics is used.

UNIT 2b

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Electro -Hydraulic

UNIT 2b

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Pneumatic

UNIT 2b

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Electro - Pneumatic

The electro-pneumatic action is a control system for pipe organs, whereby air pressure, controlledby an electric current and operated by the keys of an organ console, opens and closes valves withinwind chests, allowing the pipes to speak. This system also allows the console to be physicallydetached from the organ itself. The only connection was via an electrical cable from the console tothe relay, with some early organ consoles utilizing a separate wind supply to operate combinationpistons.

The basic operation of the system is as follows: when the organist selects a stop and depresses akey, an electric circuit is completed, causing a low-voltage current to flow from depressed key,through the stop-tab switch, and on through the cable to the electro-pneumatic relay. The relayinterprets the command from the console and sends an electric current to the appropriate solenoid.The solenoid is energized, causing the pipe valve connected to it to open, which emits compressedair into the pipe, allowing the pipe to speak.

UNIT 2b

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