Zero sequence current phase protection circuit

Published:2011/7/6 4:46:00 Author:John | Keyword: Zero sequence current | From:SeekIC

The circuit is as shown, press the start button ST to lead the KM pulls. Then the motor M runs into normal operation. At this moment, three-phase load of the motor is balanced. Secondary current of the zero sequence current transformer TA is zero. The VT1 is off and the VT2 is inducted. The relay K (JR-4 type) pulls to lead the KM to be self-locked. When the phase is broken, current induced by TA’s secondary pole is rectified by the VD1, thus turning the VT1 from the deadline state to induction state. However, the VT2 is turned from the induction state to deadline state (VT2’s power supply is picked out from the winding around generator L on the KM coil, which is about 15 ~ 18V and used to power after being rectified by the VC).



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