ELECTRIC MACHINES

Here is a 3 phase alternator stator winding. This winding was burnt due to overload in one phase. We can clearly see all coils of a phase winding is overheated and blackened. Normally this type of winding failure do not get warranty repair.

Here is an another example of burnt winding due to Insulation Failure. If you look at the first picture the winding failure will not be clear. The portion where the winding failed is marked here. Next picture is a closeup view of that portion. Here winding failure is clearly visible.

Sometimes it is very easy to find the cause of winding failure. Here this picture shows an alternator stator winding which is burnt due to the insulation failure of separation. Two nearby phase coils are separated using an insulation paper depending the class of insulation. If the IR value of that paper goes below a minimum value there will be a winding failure. It can happen in slot also. Here the insulation failure is at coupling side winding overhang. Next picture shows a close-up image of the winding were it failed.