The insulation performance of enameled wire is related […]
The insulation performance of enameled wire is related to temperature! As the temperature increases, the polymer will experience three material states: glassy, highly elastic, and viscous fluid state. The physical characteristics of these three states are as follows:
Glassy state: rigid solid solid
High elasticity: rubber-like solid, good elasticity
Viscous flow state: fluid with fluidity
In the round enameled wire test, there is a performance called softening breakdown, which is mainly to evaluate the high temperature that the enameled wire paint film can withstand. If it exceeds a certain temperature, the paint film will soften into a viscous fluid state, and it will flow like syrup.
After using enameled wire, there will be a certain amount of stress or pressure between the wires. If the temperature of the varnish film is very high, causing the varnish film to be in a viscous state, one of the pressure enameled wires will force the paint film between the paint films to flow in other directions due to pressure, which will result in the thinning of the insulating layer and the decrease of insulation performance.
If the temperature drops again, the paint film will drop from a viscous flow state to a highly elastic state, and then return to a glass state, thereby restoring better insulation properties. However, it may be reduced. The main reason is that the pressure causes the paint film to flow, which causes the paint film to be eccentric and the insulation thickness becomes thinner.
Another prerequisite is that the insulating material will not be damaged under high-temperature conditions, that is, it will not break down. If the insulating layer is damaged, the damaged point is still irreversible after the temperature drops.
Different insulation grades represent different insulation materials of the motor, and the difference in heat resistance is also the allowable temperature rise.