Chapter 1 electro mecha device part 1

Chapter 1

ELECTROMECHANICAL CONTROL DEVICES

Industrial Electronics

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A.What is Relays ?

Relays are devices that operate as an electrical switch, opening and closing under electromagnetic conditions.

One of oldest control devices still use in industrial Relays are used for electronics that have a low voltage

power source but require higher voltage to turn them on and operate. In effect, when a circuit of low power needs to be converted into a circuit of higher power.

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How Relays Works? Relays work as switch.

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Relay functionTwo primary functions;

Control large current/voltage with small electrical signal

Isolation of the power used to control the action from the power that must be switch to cause some action

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All relays can be used with DC and AC coils.

The coil does not have to work on the same voltage as the voltage being sent over the high power contacts. There is no need to send high voltage to the small switch .

The voltage and power type (AC or DC) the coil needs to operate ; that is 12Vdc, 24Vdc and 110Vac.

All relays can be used with DC and AC coils.

The coil does not have to work on the same voltage as the voltage being sent over the high power contacts. There is no need to send high voltage to the small switch .

The voltage and power type (AC or DC) the coil needs to operate ; that is 12Vdc, 24Vdc and 110Vac.

Relay Rating and Configurations

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Relay parameters When you purchase relays, you generally have control over several variables:

1. Voltage and current that are needed to activate the armature 2. The maximum voltage and current that can pass through the

armature and the armature contacts 3. The number of armatures (generally one or two) 4. The number of contacts for the armature (generally one or

two)5. Whether the contact (if only one contact is provided) is

normally open (NO) or normally closed (NC)

When you purchase relays, you generally have control over several variables:

1. Voltage and current that are needed to activate the armature 2. The maximum voltage and current that can pass through the

armature and the armature contacts 3. The number of armatures (generally one or two) 4. The number of contacts for the armature (generally one or

two)5. Whether the contact (if only one contact is provided) is

normally open (NO) or normally closed (NC)

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Relays Advantages & Disadvantages

Advantages Disadvantages

1. Relay operation can be seen: working or not, this simplified the troubleshooting

Contact wear, thus has limitation

2. Normally has multipole, multithrow, contact arrangement.

Contact bounce

3. Low initial cost Short contact life when use for rapid switching application.

4. Hold up well in extremely warm temperatures

Moving parts (springs) limit life expectancy from 1 – 3 million cycles

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Relays Applications Automatic Control (Only one starter-push button

especially in industrial) Changes Action (Normally open and Normally

close) Controlling number of component Amplify the current rating

Automatic Control (Only one starter-push button especially in industrial)

Changes Action (Normally open and Normally close)

Controlling number of component Amplify the current rating

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BREAK TIME !

Any Questions So far???

Lets Move On..

OR

Takes five??

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B. What is Solenoids What is a Solenoids?

A Solenoid is a control device that uses electromagnetism to convert electrical energy into a mechanical motion. In this device, electrical energy is used to magnetically cause mechanical movement.

There are two types of solenoids which are DC and AC solenoids.

Solenoids are used to actuate brake and/or clutch mechanisms, hydraulic valves, air valves, steam valves or other devices that require a push-pull motion.

What is a Solenoids?

A Solenoid is a control device that uses electromagnetism to convert electrical energy into a mechanical motion. In this device, electrical energy is used to magnetically cause mechanical movement.

There are two types of solenoids which are DC and AC solenoids.

Solenoids are used to actuate brake and/or clutch mechanisms, hydraulic valves, air valves, steam valves or other devices that require a push-pull motion.

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Basic Operation of Solenoids

Solenoid is an electromechanical device typically consisting of an electromagnet and a plunger.

The electromagnet cause the plunger to either move towards it or away from it, thus opening or closing a circuit.

The basic operation of a single-acting solenoid in a cutaway view. The solenoid is made up of three basic parts: Frame Plunger Coil

Solenoid is an electromechanical device typically consisting of an electromagnet and a plunger.

The electromagnet cause the plunger to either move towards it or away from it, thus opening or closing a circuit.

The basic operation of a single-acting solenoid in a cutaway view. The solenoid is made up of three basic parts: Frame Plunger Coil

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Operation of Electrical solenoidDC Types

Consists of: A coil of wire Iron core plunger Spring

Consists of: A coil of wire Iron core plunger Spring

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Operation of Solenoids AC types

Consists of: A coil of wire Iron core plunger Spring Frame

Consists of: A coil of wire Iron core plunger Spring Frame

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Selection of Solenoid In the choice of a solenoid for an application,

the following factors must be considered: The size of the mechanical load to moved

(pounds pull) The stroke distance The environment of operation The type of electrical connection The voltage and the type of current (AC or DC)

In the choice of a solenoid for an application, the following factors must be considered: The size of the mechanical load to moved

(pounds pull) The stroke distance The environment of operation The type of electrical connection The voltage and the type of current (AC or DC)

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Example application of solenoid-rest position, air supply shut off, cylinder is retracted by the spring.-when switch closed, current flow to the circuit & start to energize solenoid coil-Magnetic field created, push the plunger that will slide the valve to the right. -This will allow the air to flow inside the piston & extend the piston.-If switch released, the valve will slide back & cause the air to stop.

-rest position, air supply shut off, cylinder is retracted by the spring.-when switch closed, current flow to the circuit & start to energize solenoid coil-Magnetic field created, push the plunger that will slide the valve to the right. -This will allow the air to flow inside the piston & extend the piston.-If switch released, the valve will slide back & cause the air to stop.

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BREAK TIME !

Any Questions So far???

Lets Move On.. OR Takes five??

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C. What is Timer ? Device that provide a delayed action between the

time an event is initiated and the time that the event is actually performed

Used many types in industrial electronic controls. In industrial, timers may be used in a fluid power control system to delay any action such as the start up of cylinder or to establish a dwell period at one end of a cylinder’s travel before retracts.

Many types of timer are available, some motor driven and some solid state.

Device that provide a delayed action between the time an event is initiated and the time that the event is actually performed

Used many types in industrial electronic controls. In industrial, timers may be used in a fluid power control system to delay any action such as the start up of cylinder or to establish a dwell period at one end of a cylinder’s travel before retracts.

Many types of timer are available, some motor driven and some solid state.

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Type of timer

Dashpot timer Synchronous clock

timer Solid state timer Programmable timer

Dashpot timer Synchronous clock

timer Solid state timer Programmable timer

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Type of timer…cont1) Dashpot timer- control how rapidly air or liquid is allowed to pass into or out of the container through an orifice (opening) either fix in diameter or variable.

1) Dashpot timer- control how rapidly air or liquid is allowed to pass into or out of the container through an orifice (opening) either fix in diameter or variable.

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Type of timer…cont2) Synchronous clock

-Timer that opens/close a

circuit depend on the

hand of the clock

2) Synchronous clock

-Timer that opens/close a

circuit depend on the

hand of the clock