what is a Relay ?
Posted by Unknown on Wednesday, July 02, 2014 with No comments
A Relay is an electromagnetic device which is used to isolate two circuits electrically and connects them magnetically.
It is basically used in intrerfacing electronic circuit to an electric circuit. it means that a small DC voltage drives circuits working at large voltages like 230V AC (as in our homes).
A Relay consist of two parts
1. Input
2. Output
Input consist of a coil which gets energized when a voltage with appropriate magnitude is applied to it ( this voltage is known as Operating voltage). when the coil gets energized it generates a magnetic field which is responsible for the switching action of a relay.
Output consist of three contactors viz, NO,NC and COM.
NC- normally closed- In normal state or energized state the COM is connected to NC.
NO- normally open- In energized state COM gets connected to the NO.
When the DC voltage is applied at the input of relay the input coil gets energized by the applied voltage and generates magnetic field , this magnetic field switches over the COM contactor to NO
contactor. in this way switching takes place. and when the circuit gets denergized on the input side the COM is back to NC by a spring mechanism.
Types of relays-
1. DPDT
2.SPST
3.SPDT
4.DPST
DPDT- Double pole double throw - used to control two circuits , it has 6 pins. generally used in robotics applications.
SPST- Single pole single throw - it is used for normal switching applications like ON/OFF.
SPDT- Single pole double throw- it is used for selecting "either" of the two power supplies. for eg. switching from 12V DC supply to 24V DC supply in a circuit.
It is basically used in intrerfacing electronic circuit to an electric circuit. it means that a small DC voltage drives circuits working at large voltages like 230V AC (as in our homes).
A Relay consist of two parts
1. Input
2. Output
Input consist of a coil which gets energized when a voltage with appropriate magnitude is applied to it ( this voltage is known as Operating voltage). when the coil gets energized it generates a magnetic field which is responsible for the switching action of a relay.
Output consist of three contactors viz, NO,NC and COM.
NC- normally closed- In normal state or energized state the COM is connected to NC.
NO- normally open- In energized state COM gets connected to the NO.
When the DC voltage is applied at the input of relay the input coil gets energized by the applied voltage and generates magnetic field , this magnetic field switches over the COM contactor to NO
contactor. in this way switching takes place. and when the circuit gets denergized on the input side the COM is back to NC by a spring mechanism.
Types of relays-
1. DPDT
2.SPST
3.SPDT
4.DPST
DPDT- Double pole double throw - used to control two circuits , it has 6 pins. generally used in robotics applications.
SPST- Single pole single throw - it is used for normal switching applications like ON/OFF.
SPDT- Single pole double throw- it is used for selecting "either" of the two power supplies. for eg. switching from 12V DC supply to 24V DC supply in a circuit.
Categories: BasicElectronics
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