Judge the contactor is good or bad
listen: A, listen to whether it has a very loud squeaky sound, if possible may be (1) the power supply voltage is low
the amount of power to control the end of the line to remove the control, with a multimeter to beat the amount of foot, press the test end of the three main contacts and another group of normally open contacts, should be conductive
smell: smell a smell there is no Jiao smell, if checked please look at the winding and contacts.
contact points on the dirt or moving iron core contact surface dirt. If you hear Kaka - contactor can not absorb the sound, mostly for two cases
