Three-phase asynchronous motor winding short circuit phenomenon

(1) External observation method. Observe whether the junction box and the end of the winding are burnt. After the winding is overheated, it will leave dark brown and smell bad.

(2) Temperature detection method. Run without load for 20 minutes (stop immediately if any abnormality is found), and use the back of your hand to feel whether the temperature of each part of the winding exceeds the normal temperature.

(3) Electricity test method. Use an ammeter to measure, if the current of a certain phase is too large, it means that there is a short circuit in this phase.

(4) Bridge inspection. Measure the DC resistance of each winding, generally the difference should not exceed 5%, if it exceeds, the phase with the smaller resistance has a short circuit fault.

(5) Short-circuit detector method. If there is a short circuit in the winding under test, the steel sheet will vibrate.

(6) Multimeter or megger method. Measure the insulation resistance between any two-phase windings. If the reading is extremely small or zero, it means that there is a short circuit between the two-phase windings.

(7) Voltage drop method. After the three windings are connected in series, the low-voltage safe alternating current is connected, and the group with a small reading is found to have a short-circuit fault.

(8) Current method. When the motor is running without load, first measure the three-phase current, and then measure and compare the two phases. If it does not change with the power supply, there is a short circuit in the one-phase winding with the larger current.