Determining the cause of motor burning and assigning responsibility involves a systematic approach that looks at various aspects of the motor’s condition, its operating environment, and its maintenance history.
1.the winding becomes locally blackened:this can be classified as either an inter-phase short circuit or a turn-to-turn short circuit, depending on whether it occurs within the same phase. This is typically caused by contaminants inside the winding or damage and wear to the enamel-coated wire. If the motor has never been opened, these issues are usually attributed to the motor manufacturer.
Inter-phase short circuit
Inter-turn short circuit
2.part of the winding turns completely black: depending on the motor's wiring method, there are two different manifestations, as shown in the two pictures below. This situation is usually caused by a phase loss and can generally be determined to be the responsibility of the user.
Star connection motor burned out of phase
Triangle connection motor burned out of phase
4.Short circuit at the lead-out wire connection: usually caused by internal pollution, poor insulation, or poor contact at the joints. It is generally determined to be the responsibility of the motor manufacturer.
5. Local grounding fault. This is usually caused by contact between the enameled wire and the core, or the front and rear end covers, resulting in local burning. Specific causes may include: damaged slot insulation, sharp or misalignment of lamination, excessive winding dimensions, or insufficient creepage distance reserved,etc. It is generally determined to be the responsibility of the motor manufacturer.
Due to the complexity of the motor structure and operating conditions, the assignment of responsibility is only approximate (not 100%).
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