Correct Answer - Option 4 : F or higher
Motor and Generator Insulation Systems:
Insulation is a limiting factor in the design of an electrical machine. If the thickness of the insulation is increased, the space available for the current carrying conductor is reduced and the conduction of heat from the conductor to the iron is restricted. Requirements of an insulation system for machine stator windings are
- High dielectric strength
- High resistance to partial discharges (PD)
- High thermal conductivity
- Good resistance to abrasions
- Good resistance to tape separation caused by thermal heating
- Good resistance to moisture and oil vapor
Class F or higher class is suitable for DG sets.
Class F: This insulation is rated for a total temperature of 155°C. It is made of materials or combinations of materials such as mica, glass fiber, asbestos, etc., with suitable bonding substances capable of operation at 155°C.