XNUMX. Whether the capacitor is short-circuited

　　If this kind of fault is a single-phase motor, it is likely that the capacity of the running capacitor has become smaller or there is a slight short circuit.To judge whether the capacitor is short-circuited, in addition to measuring with a multimeter, you can also touch the capacitor by hand: if the temperature is high, it means that the capacitor has a short-circuit phenomenon and should be replaced.If the temperature is normal, it is slightly higher than the hand temperature.

　　Second, see if the three-phase current is balanced

　　Check whether the three-phase current is balanced, such as unbalanced three-phase current: the main reason is that the power supply voltage is severely unbalanced and a certain phase of the motor is partially short-circuited.If the power supply voltage is severely unbalanced, you can ask the power department to deal with it.If the internal turns of the motor are short-circuited, find the fault point and deal with it.Consider rewinding if necessary.If the three-phase currents are basically balanced, the reason is that the power supply voltage is too low or the rotor is broken.

　　Third, check whether the connection line is loose or has poor contact

　　If it is a three-phase motor, in addition to checking whether the input voltage is low, it is also necessary to check whether the three-phase input is balanced.Excluding the above two factors.You can also touch the temperature rise of the motor by hand.When the load is very light and the motor temperature rises very high in a short period of time, it may be a short circuit between turns.In addition, you can use the nose smell method to further determine the short circuit between the turns.Open the motor wiring cover, cut off the power supply, and use your nose to approach the terminal. If there is a burning smell and the motor temperature rises quickly, it is judged as a three-phase inter-turn short circuit.

　　XNUMX. Desoldering of the squirrel cage ring of the three-phase motor

　　Desoldering of the squirrel cage ring of the three-phase motor, serious distortion of the silicon steel sheet lamination, etc. can also cause this kind of failure, but the probability of this kind of failure is low.In addition, the slip ring of the three-phase slip ring excitation motor is severely worn, the pressure of the slip ring spring is insufficient to cause poor contact of the carbon brush, and the short circuit caused by the carbon in the slip ring gap can cause insufficient excitation current, etc., all of which can cause such failures.