the circuit of loss-of-phase protecting relay for electric motor (4)

Published:2011/6/16 8:29:00 Author:Ariel Wang | Keyword: loss-of-phase , protecting, relay, electric, motor | From:SeekIC

When there is one phase missing in three-phase power supply ,it will generate around 12V AC voltage between A point and zero line N rapidly.It is commutated by VD1-VD4 and filtered by C4.VS is conducted.C5 begins to charge.After a few minutes(after C5 finishes charging),VU is conducted.VL is lighted.K pulls in.normally-closed contact is disconnected.Then AC contactor is released.The working power supply of electric motor M is cut down .When three-phase power supply is normal,K is released.Then you can press start push button to restart the electric motor.



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