Manual for Induction Motors and Generators
78 -
Maintenance
3BFP 000 050 R0101 REV E
7.6 Maintenance of stator and rotor windings
The windings of rotating electrical machines are subjected to electrical, mechanical and thermal
stresses. The windings and insulation gradually age and deteriorate due to these stresses.
Therefore, the service life of the machine often depends on the insulation durability.
Many processes leading to damages can be prevented or at least slowed down with appropriate
maintenance and regular testing. This chapter offers a general description on how to perform
basic maintenance and tests.
In many countries, ABB Service offers complete service maintenance packages, which include
comprehensive testing.
Before conducting any maintenance work on the electrical windings, general electrical safety
precautions are to be taken and local regulations are to be respected in order to prevent
personnel accidents. See
Chapter 7.2 Safety precautions
for more information.
Independent test and maintenance instructions can also be found in the following international
standards:
1. IEEE Std. 43-2000, IEEE Recommended Practice for Testing Insulation Resistance of
Rotating Machines
2. IEEE Std. 432-1992, IEEE Guide for Insulation Maintenance for Rotating Electrical
Machinery (5 hp to Less Than 10 000 hp)
7.6.1 Particular safety instructions for winding maintenance
Some of the hazardous works of the winding maintenance include:
•
Handling of hazardous solvents, varnishes, and resins. Hazardous substances are required
for cleaning and re-varnishing windings. These substances can be dangerous if inhaled,
swallowed or in any contact with skin or other organs. Seek proper medical care if an
accident occurs
•
Dealing with flammable solvents and varnishes. Handling and use of these substances
should always be by authorized personnel and proper safety procedures must be followed
•
Testing at high voltage (HV). High-voltage tests should only be conducted by authorized
personnel and proper safety procedures must be followed.
Dangerous substances used in winding maintenance are:
•
White spirit: solvent
•
1.1.1-trichloroethane: solvent
•
Finishing varnish: solvent and resin
•
Adhesive resin: epoxy resin.
NOTE: There are special instructions for handling dangerous substances during maintenance
work. These instructions must be followed.
Some general safety measures during winding maintenance are as follows:
•
Avoid breathing air fumes: ensure proper air circulation at the work site or use respiration
masks
•
Wear safety gear such as glasses, shoes, hardhat and gloves and suitable protective
clothing to protect the skin. One should always use protective creams
