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Answering motor problems

We all know that three-phase motors have winding-to-turn short-circuits, winding-to-window shorts, and winding-to-pole shorts due to insulation damage caused by excessive motor currents, excessive power supply voltage fluctuations, single-phase operation, mechanical bumps, and poor manufacturing. Short-circuit to the winding. For this phenomenon, we need to carry out several inspection methods:

⑴ external observation method. Observe whether the terminal box and the winding ends are scorched. After the winding is overheated, it will remain dark brown and have an odor.

⑵Temperature detection method. Run for 20 minutes at no load (stop immediately when abnormality is found), and check if the parts of the winding exceed the normal temperature with your back.

(3) Power-on experiment method. Measure with an ammeter. If the current of one phase is too large, it indicates that there is a short circuit in that phase. ⑷Bridge inspection. Measure the DC resistance of each winding. Generally, the phase difference should not exceed 5%. If it exceeds, the phase with a small resistance has a short circuit fault.

⑸ Short Circuit Scout Method. If the winding under test is short-circuited, the steel sheet will vibrate.

⑹Multimeter or megohm method. Measure the insulation resistance between any two-phase windings. If the reading is very small or zero, it indicates that there is a short circuit between the two-phase windings.

⑺Voltage drop method. After the three windings are connected in series, low-voltage safe AC power is passed in, and a group with a small reading has a short-circuit fault.

⑻Current method. When the motor is running at no load, the three-phase current is measured first, and the two-phase current is measured and compared. If it does not change with the power supply swap, the one-phase winding of the larger current has a short circuit.

#motor problem

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