Introduction: How to judge the cause of the burn based on the burnt state, and analyze whether it is the responsibility of the producer or the user. Today we will share with you some typical cases.
All windings are burnt black: usually caused by the motor being overloaded, stalled, the voltage being too high or too low, starting and stopping too frequently, etc. This can basically be judged to be the responsibility of the user.
Some windings all turn black: According to the different connection methods of the motor, there are two different manifestations, as shown in the two figures below. This situation is usually caused by a lack of phase, and it can basically be determined to be the user's responsibility.
Partial blackening of the winding: Depending on whether it occurs in the same phase, it is divided into phase-to-phase short circuit fault and inter-turn short circuit fault. This is usually caused by the presence of contaminants inside the windings, damage and wear to the enameled wires. If the motor has not been opened, the responsibility usually falls on the motor manufacturer.
Local ground fault: usually caused by local burnout caused by contact between the enameled wire and the core, or the front and rear end covers. Specific reasons can be: slot insulation damage, sharp or misplaced punching sheets, winding size out of tolerance, insufficient creepage distance reservation, etc. Generally, it can be determined that the motor manufacturer is responsible.
