COIL AND INSULATION IN HIGH VOLTAGE MOTORS

Inspection And Maintenance

It is desirable that the insulation for the coil of motors is to be carefully kept clean and always dry. Therefore, the ventilating duct and the protective cover are so arranged as to be suitable for each part, and also be designed to reduce containmination, in some case, motor must be heated by means of a space heater to prevent dew drops due to change of motor temperature.

Cleaning Of Coils

Keeping all the insulating materials clean is of much importance. Dust and foreign substances (carbon, copper, power dared mica, etc), in some case, clog the ventilating port, thereby reducing the air flow, and making the dissipation of heat difficult, and thus overheating motors locally or entirely. In case that accumulated fine particles are electrically conductive or produce a conductive pasty adhesive by absorbing water or oil, they finally cause short circuit of coils and earthing troubles; and wearing by fine particles damages insulating materials. It should be noted that the adhesion of oil is not harmful, but cause adhesion and accumulation of various contaminants.

METHODS OF CLEANING

Cleaning by wiping with cloth

Wiping with cloth is effective for removing only dust or foreign substances loosely adhering to components which can be reached by hand from outside. Use a clean dry lint-free cloth so that no waste material will adhere to the surface.

Cleaning by blowing compressed air

This method. is particularly effective for removing dry dust or foreign matters loosely adhering to the parts, which cannot be reached by hand from outside. The compressed air should be clean and dry, and at" pressure of 3-4 kg/cm2. Before blowing the compressed air against the coil, blow off water completely from the air pipes and hoses. The air must be filtered so that no adhesive particles can invade and damage the insulated portion or go under the insulation tape. Open both ends of the motor to provide a proper outlet for air and dust before starting to blow the compressed air. Even if the compressed air is blown against, this cleaning method is not effective unless dusts are taken outside of the motor in a proper way.

Cleaning by means of solvent

Cleaning with solvent is effective for removing solid or stubborn dirt adhering to insulated surfaces, especially mixtures of grease, oil carbon and dust. After applying solvent, wipe off with clean cloth and then dry. Out recommended solvent is*the Rubber Benzine (JIS K2201-2 or Equivalent).

Caution

When using a solvent, give full attention to the prevention of fire, explosion, and toxication. Besides the above cleaning methods, a steam cleaning method or a desalinating method can be available.


COIL AND INSULATION IN HIGH VOLTAGE MOTORS PART 2....... SOON