A very critical step when carrying out maintenance work on the motor is to cut off the power. If the motor is repaired without power failure, the high voltage of the motor will hurt the human body. The voltage coefficient of the high voltage is very high, which can cause physical disability in minor cases and death in serious cases.

Therefore, in the maintenance of the motor, it is a must to do a power outage. After the motor is disassembled, the plug of the power supply must be sealed with insulating material (insulating cloth or insulating paper), and the outer casing and the remaining wires must be short-circuited and grounded.

After the overhaul, the fixing work of the motor should also be done well. If the motor is not fixed properly, it is easy to leak during transportation, and people may be injured or killed.

If the motor is unstable and falls off during petroleum processing, and the motor falls into the container machine with high temperature and overturns it, the casualties will be very serious. Therefore, after the motor is repaired, the work must be better in the details.

There are many examples of short-circuiting between phases or phase-to-ground at the ends due to poor insulation quality of the handbag at the end. The insulating cladding of the handbag is not tight, and there is a gap inside. When the ambient humidity is high, the insulation performance of the winding will be significantly reduced until the surface of the insulating material is dew, and the insulating surface is easy to cause creeping discharge. The discharge mechanism is that a water film is first formed on the insulating surface under the action of an electric field.