INSULATING VARNISHES
Varnish coating, also called Secondary Insulation, is an important component of the insulation
system of an electrical machine. Varnishes, of different types are used in the insulation system
of electrical machines for impregnation and finishing applications. Advantages of these coatings
are:
- Increased mechanical bonding to the winding wires
- Improved dielectric properties
- Improved thermal conductivity
- Protection to the winding against moisture and chemically corrosive environment.
Varnishes are classified based on:
1. Applications of varnish.
2. Type of (varnish) curing method.
3. Based on main raw material used in varnish.
Insulating varnish based on applications:
1. Impregnating varnish
2. Finishing varnishes
3. Core plate varnishes
4. Bonding varnishes
5. Special purpose varnishes
Main raw material used: Alkyd Phenolic, Alkyd, Polyurethane, Isophthalic Alkyd, Modified
polyester, Epoxyester Melamine, Polyestermide, Epoxy, Phenolic, Phenolic Melamine - based.
The above varnishes come in Solvent based and Solvent-less based.
