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Draw and explain the control and power diagram for D.C. injection Braking.

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Circuit Operation 

1)Starting & Running - Pressing the start button S2 will energise coil C2 provided the stop button S1 is not pressed and the overload OL2 has not tripped. The retaining contact of C2 will keep the contactor energised when the start button S2 is released. The motor then runs up to speed. 

2)Stopping & Braking - Pressing the stop button S1 will de-energise contactor C2 and energise contactor C3 provided the start button S2 is not pressed. The retaining contact of C3 will keep the contactor energised when the stop button S1 is released. This causes the motor to stop due to the injection of DC. C3 will remain energised until the timer CR finishes timing. Then its normally closed contact will open de-energising C3 and removing DC from the stator. This in turn de-energises the timer coil. 

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