How to dry the motor?

Update:14 Sep 2018
Summary:

Introduction: At the beginning of the motor drying proc […]

Introduction: At the beginning of the motor drying process, as the moisture is evaporated by heat, the insulation resistance is lower, then gradually increases, the rising resistance becomes slower and slower, and finally stabilizes at a certain value. When the motor insulation resistance rises above the acceptable value and remains constant for 6 hours, the process ends.
The purpose of the motor drying process is to drive out the moisture in the windings and improve the insulation performance. If the insulation is very low and the drying process is not carried out, the power supply is used, which is likely to cause an insulation breakdown accident.

There are many methods for drying the motor. Generally, there are two methods of hot drying and current heating. When drying, pay attention to control the temperature, avoid excessive temperature and damage the motor insulation. The drying temperature of the motor of Class A insulation should not exceed 85 degrees, and the insulation of Class E should not exceed 95 degrees.

The hot baking method is carried out in an electric oven. The top of the oven should have a vent hole to facilitate the discharge of moisture. Most electric ovens have an automatic temperature control device that can maintain a constant temperature. In addition, there are other hot baking methods such as infrared rays.

The current heating method is to pass the electric current into the stator winding to turn the electric energy into heat energy for drying. At the beginning, the current should be controlled to 20%-30% of the rated current of the motor, and then gradually increase by 50%-60%. Generally available The autotransformer is easy to adjust as a power source. It is also possible to connect several motors with close capacity in series and connect them to a 220V AC power supply.

At the beginning of the motor drying process, since the moisture is evaporated by heat, the insulation resistance is low, and then gradually increases, the resistance of the rise is slower and slower, and finally stabilizes at a certain value. When the motor insulation resistance rises above the acceptable value and remains constant for 6 hours, the process ends.