Normal operation as the main power switch on the AC contactor

In use there, the normal closing operation as a total power 4OA AC contactor, and then operate a motor closing any other AC contactor, the total supply of both the control Bo OA AC contactor is disconnected. Disconnect motor circuit without load at startup, this  mcb circuit breaker  still exists. Therefore array analysis in machine electric stick into the line terminals, check with voltage tester has power display, with three-phase AC voltage meter to check the line voltage, phase voltage are in line  air circuit breaker . AC contactor without 4OA as the main power control, respectively, with AC contactor control 4 motors can work, but at the same time start two or more motors, the AC  electric transformer  on the trip. And starting with the direct method, you can also start the four electric motors. Find the above analysis, the total power and time lines identified no problems, the fault should be out in the second line.