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7.6 Maintenance of stator and rotor winding
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 also 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.
•
Trichloroethane: solvent.
•
Finishing varnish: solvent and resin.
•
Adhesive resin: epoxy resin.
NOTE: There are special instructions for handling dangerous substances during
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.
maintenance work. Important handling instructions can also be found on
warning labels of the packing.
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