Method of motor maintenance:

(1) Observation method. Most of the breakpoints occur at the end of the winding, checking for any collisions or joint detachment.

(2) Multimeter method. Using a resistance range, connect one meter rod to the center point of the "Y" shape in the "Y" type connection method, and connect the other rod to the first end of the three-phase winding in sequence. The infinite phase is the breakpoint; After the short circuit connection of the "△" type connection method, measure each group of windings separately, and the infinitely large one is the breaking point.

(3) Lamp test method. The method is the same as before, and the phase that does not light up is an open circuit.

(4) Megohmmeter method. The phase where the resistance tends towards infinity (i.e. not zero) is the breaking point.

(5) Ammeter method. When the motor is running, use an ammeter to measure the three-phase current. If the three-phase current is unbalanced and there is no short circuit phenomenon, there is a partial short circuit fault in the lower current phase winding.

(6) Electric bridge method. When the resistance of one phase of the motor is greater than that of the other two phases, it indicates that there is a partial open circuit fault in the winding of that phase;

(7) Current balance method. For the "Y" type connection method, the three-phase windings can be connected in parallel and a low voltage and high current AC power can be applied. If the current difference in the three-phase windings is greater than 10%, the end with the small current is open circuit; For the "△" type connection method, first disconnect one contact of the stator winding, and then apply low voltage and high current phase by phase, with the low current phase being a circuit breaker.

(8) Broken cage scout inspection method. If the rotor cage is broken during inspection, the reading of the millivoltmeter should decrease.