the circuit of loss-of-phase protecting relay for electric motor (5)

Published:2011/6/17 23:25:00 Author:Ariel Wang | Keyword: loss-of-phase, protecting, circuit , relay , electric , motor | From:SeekIC

When starting button is pressed,the voltage between L2 and L3 go to AC contactor KM through Stop button 51,start push button 52 ,the normally-closed contact of relay K and contact of thermal relay KR.KM pulls in.The electric motor gets to work.It provides 12V DC voltage for relay-driven circuit(consist of V1,V2,VD2 and K) after it is reduced by T,commutated by VD3 and filtered by C2. At the same time,it lights up VL.When three-phase (L1,L2,L3) AC voltage is normal,the voltage is 0V between the plus terminal of VD1 (the Y-connected middle point) and zero line N.V1 is not conducted with V2.K is released.



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