State the function of seal in circuit w.r.t. PLC.

State the function of seal in circuit w.r.t. PLC.
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Answer :

Standard Start-Stop-Seal circuit: 

* The Start-Stop-Seal circuit is as shown in figure. The power circuit consists of 3ph load (Motor) connected by a main contactor (M) to 3-phase supply. The control circuit consists of Start, Stop push-buttons and main contactor coil (M). 

* When Start push button is pressed, the contactor coil (M) gets energized and the motor is connected across supply. When Start push-button is released, supply to coil M is maintained through RUN (aux contact of M). 

* When STOP is pressed, M gets de-energized and motor gets disconnected from supply.


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