There are the following methods to judge whether the three-phase asynchronous motor is faulty:

⑴ observation method. Observe whether there are traces of damage and scorch by visually inspecting the winding ends and the insulation in the slot. If there is, it is the grounding point.

⑵ multimeter inspection method. Check with the low resistance gear of the multimeter, if the reading is small, it is grounded.

(3) Megohmmeter method. According to different grades, use different megohmmeters to measure the insulation resistance of each group of resistors. If the reading is zero, it means that the winding is grounded. However, if the motor insulation is damped or broken down due to accidents, it should be determined based on experience. Generally speaking, When the pointer swings at "0", it can be considered that it has a certain resistance value.

⑷ test lamp method. If the test light is on, it means that the winding is grounded. If there is sparks or smoke somewhere, it is the winding grounding fault point. If the light is dimly lit, the insulation has ground breakdown. If the light does not light up, but there is also a spark when the test rod is grounded, it means that the winding has not been broken down, but is severely damp. You can also use hardwood to tap on the edge of the shell, and when it hits a certain place and waits for one off and one light, it means that the current is on and off, and that place is the grounding point.

⑸ current burning method. With a voltage regulating transformer, after connecting to the power supply, the grounding point heats up quickly, and the place where the insulating material emits smoke is the grounding point. Special attention should be paid to the small motor not exceeding twice the rated current for less than half a minute; the large motor is 20%-50% of the rated current or the current is gradually increased, and the power is turned off immediately when the grounding point just emits smoke.

⑹ Group elimination method. For the grounding point inside the iron core and the burning is relatively severe, the burned copper wire and the iron core are fused together. The method used is to divide the grounded one-phase winding into two halves, and so on, and finally find the grounding point.

YE4 SERIES THREE PHASE ASYNCHRONOUSMOTOR

Ambient Temperature	-15℃~+40℃
Relative Humidity	Not Exceed 90%(below 20℃)
Rated Voltage	380V
Rated Frequency	50Hz
Insulation Class	F Class
Duty	Continuous Duty S1
Cooling Method	IC411
Ingress Protection	lP55
Connection	Y connection for 3KW and below connection for 3KW above