How to protect three phase motors from moisture in humid environments-QIJUN MOTOR

1. Source of moisture
In a humid environment, it is easier for moisture to enter the inside of the motor than in a normal environment. To sum up, the main sources of moisture are as follows:

(1) Motors running outdoors are directly exposed to rain, and a small amount of water enters the inside of the motor through the gap on the explosion-proof surface;

(2) When the motor stops working in a humid environment, moisture enters the inside of the motor and condensation occurs;

(3) Motors stored for a long time are susceptible to moisture and condensation due to moisture intrusion;

(4) Motors working in harsh environments may suffer from flooding, immersion and other accidents, causing moisture to enter;

(5) During the motor production process, moisture remains in the insulation capillary pores caused by failure to perform pre-baking according to process requirements or incomplete drying after varnish dipping.

2. Hazards caused by moisture inside the motor

For motors, good insulation is a prerequisite for the safe operation of the motor.
In the winding stator, whether it is slot insulation, interlayer insulation, interphase insulation, binding tape and the outer layer of the power lead wire, there are a large number of capillary pores, which are very easy to absorb moisture in the air, reduce its own insulation performance and make the insulation thermal conductivity worse,causing insulation breakdown and damage to the motor, causing personal and equipment safety accidents.

3. Waterproof measures for the shell of explosion-proof motors

The main waterproof protection object of the motor is the motor casing. The waterproof performance of the motor depends on the protection provided on the casing. In order to reduce the presence of moisture inside the motor, the waterproofing process of the casing is generally solved in two aspects. The first is to take measures to prevent the entry of moisture; the second is how to discharge the moisture in a timely and effective manner after it enters.

Focusing on these two aspects, we can provide the following effective protection on the shell:

(1) Add a water retaining ring or rainproof cap to the motor shaft extension.

(2) Use shaft surface oil seals with better dustproof and waterproof effects to replace ordinary V-rings.

(3) Motors with special installation methods, such as V1 motors, must be equipped with a top cover on the wind hood.

(4) Add a sealing ring to the flameproof surface of the stop.

(5) Apply sealant to the important joint surfaces of the motor and the fastening screw holes on the stator.

(6) Add an explosion-proof breathing and drain valve to the stator.