Why would you need to use electrical resin when most wires already come with a layer of primary insulation?
In one word,in order to improve its operating characteristic of electrical apparatus
How to put varnish on coils?
Insulating varnish comes in liquid form and can be sprayed, brushed, or trickled onto coil windings. The method of application depends on the size of the coil and the desired production rate, and different methods for insulation varnish, such as the dip and bake method, vacuum pressure impregnation (VPI), and trickle impregnation can result in different degrees of impregnation of the winding. The use of solvents also plays an important role in diluting insulating varnish so that it will flow more easily.
In general,the varnished coil need 3-6 hours for natural air drying
Benefits of varnish?
Electrical resin:
- Provides protection from mechanical damage
- Dampens vibrations by immobilizing windings
- Prevents moisture and other foreign matter, like dust and debris particles, from getting in between coils and damaging the primary insulation
- Increases the dielectric strength (i.e. improves insulating properties) of fibrous insulation (e.g. paper was commonly used as primary insulation for the coils in very old transformers)
- Helps carry heat away from the windings either to the surrounding air or to the core
Electrical resin (i.e. secondary insulation or impregnating resin) is used to provide extra protection for wire windings and coils. This is especially important for inductor coils where the coils are packed so tightly that internal damage from coils rubbing against each other could easily cause their primary insulating layer to wear out.
