What to do if the winding of Haicheng asynchronous motor is short-circuited

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What to do if the winding of Haicheng asynchronous motor is short-circuited

author:xiaoE date:2020-01-08 13: 07

　　becauseMotor current is too large, Power supply voltage fluctuation is too large, single-phase operation, mechanical bumps, poor manufacturing, etc., resulting in insulation damage, such as short-circuit between winding turns, short-circuit between windings, short-circuit between winding poles and short-circuit between windings.

　　1. Malfunction

　　The magnetic field of the ions is unevenly distributed, and the three-phase current is unbalanced, which increases the vibration and noise when the motor is running. The motor cannot be started in severe conditions, and a large short-circuit current occurs in the short-circuit coil, which causes the coil to rapidly heat up and burn.

　　2. Cause of occurrence

　　Long-term overload of the motor will make the insulation aging and lose its insulation effect; insulation damage occurs when the wire is embedded; the winding is damp and the insulation resistance decreases to form an insulation breakdown; the end and interlayer insulation materials are not properly padded or damaged during shaping; the end connection line insulation Damage; insulation breakdown due to overvoltage or lightning; the rotor and stator winding ends rub against each other to form insulation damage; metal foreign objects fall into the motor and excessive oil pollution.

　　3. View method

　　⑴ External investigation method.Investigate whether the junction box and the ends of the windings are burnt, and the windings leave dark brown and smelly after overheating.

　　⑵The method of detecting temperature.No-load operation for 20 minutes (stop immediately when an abnormality is found), and check whether each part of the winding exceeds normal temperature with the back of the hand.

　　⑶ Electric experiment method.Measure with an ammeter. If the current of a certain phase is too large, it indicates that the phase has a short circuit.

　　⑷View by electric bridge.Measure the DC resistance of a winding. Generally, the phase difference should not exceed 5%. If it exceeds, the phase with the smaller resistance will have a short circuit.

　　⑸ Short-circuit detector method.If the tested winding has a short circuit, the steel sheet will oscillate.

　　⑹Multimeter or megohmmeter method.Measure the insulation resistance between any two-phase winding phases. If the reading is extremely small or zero, it indicates that there is a short circuit between the two-phase winding phases.

　　⑺ Voltage drop method.After connecting the three windings in series, they are connected to low-voltage safe alternating current, and it is found that the group with the small reading has a short circuit problem.

　　⑻ Current method.When the motor is running under no load, first measure the three-phase current, and then measure and compare the two-phase exchange. If it is not changed with the power supply exchange, the one-phase winding of the larger current has a short circuit.

　　4. Short-circuit treatment method

　　⑴ The short-circuit point is at the end.The short-circuit point can be separated by insulating material, or the insulated wire can be re-wrapped, then painted and re-dried.

　　⑵ Short circuit in the wire slot.After softening it, find the short-circuit point and correct it, put it into the wire slot from the beginning, and then paint and dry it.

　　(1) For each phase winding with short-circuit turns less than 12/XNUMX, cut off all short-circuit wires when the number of turns in series is connected, and connect the conductive parts to form a closed loop for emergency use.

　　⑷ When the number of turns at the short-circuit point of the winding exceeds 1/12, all rewinding shall be removed.