It consists of the groundwall insulation and turn to turn insulation. Typically for induction motor insulation is the slot of paper to protect between cooper and ground surface.For phase to phase insulation normally used sheet of insulation paper laid between phase.
What is the insulation of electrical motor?
For more protection,normally all winding cover by insulation varnish. The important things is we must know the root cause for insulation failures because we can prevent it from happened.
From discussion and technical study,the most electrical insulation failures are caused by a combination of the voltage spikes that occur at start up and normal deterioration.
Causes of insulation failures.
Normally electrical motor insulation can be effected by many factors.Below are several common factors that effected the insulation failures.
1) Contamination : A chemical reaction or deposit on the windings that cause deterioration of the varnish insulation.
2) Mechanical : Some of movement or vibration between the winding coil or the motor body can wear the insulation system.
3) Over voltage spikes : High voltage surges or spikes can cause from VFD without filter,inrush switching or lighting.
4) Early thermal aging : High temperatures or excessive causing premature failure such as varnish insulation damage or weak.
5) Normal thermal aging : The slow deterioration of the insulation over the windings natural life through normal operation.
6) Moisture : If the environment condition so bad with high humidity and moisture,it can generated water into the winding and can cause the rusty and short-circuit.
7) Dust / dirty : The dust accumulated at winding surface or armature day by day.This can cause a winding slowly overheat and in the end it can cause the winding insulation failed or damage due to high heat.