Because of the low voltage in operation, there is little chance of overvoltage caused by the turn-to-turn insulation of rotor poles. Under normal circumstances, there will be no turn-to-turn short circuit, especially for class B and above insulation, and the faults are mostly thermal aging or original defects. Therefore, the magnetic poles that have been identified as inter-turn insulation problems in testing should be carefully cleaned, especially when there are impurities such as welding slag and solder drops in the inter-turn gap. Because they are covered by external paint, the metal particles in the gap can easily lead to the judgment that the turn-to-turn insulation is zero, so the turn-to-turn insulation should be thoroughly cleaned before the electrical test is carried out to confirm. If the fault point cannot be found by visual inspection, low voltage and high current should be applied according to the size of the magnetic pole coil. If there is a turn-to-turn short circuit, the fault location will rise rapidly, thus determining the fault location.

The procedure of rotor turn-to-turn insulation treatment is basically similar to the above problems. If the turn-to-turn short circuit is not in the first and second turns, the treatment is a little more complicated.

After the coil is decomposed, aim at the turns to be separated with a special chopping axe (copper) or a suitable wooden wedge, hit the tail of the axe or wooden wedge with a sledgehammer, split the turns, and pad the turns on both sides with another wooden wedge. Remove damaged insulation (usually local), and pay attention to whether there are burrs or edges on the wire, and the surface of the wire should be smooth and flat. After the surface of copper wire is cleaned, the insulation layer is placed under the wire. Epoxy glass blank is mostly used for class B insulation.