DC geared motors are widely used in the steel industry and machinery industry. The following editors will analyze some faults of the geared motors:

1. The motor will not start after being energized. In addition to the fault of the power supply circuit and the motor windings, most of the faults are abnormal starting circuits of the motor. Electric fans, exhaust fans, washing machines and other motors generally use capacitors to start the operation; while refrigerators, freezers and other motors mostly use resistors to split the phase to start the operation. Once the capacitor or split phase resistance in the startup circuit is damaged, the motor cannot operate normally. Check the motor for faults after rectifying the startup circuit fault. If the starting circuit is normal, it may be a local short circuit or an open circuit in the internal windings of the motor, which can be judged by measuring the resistance of each winding with a multimeter R × 1. Such as the refrigerator compressor motor, under normal circumstances the starting winding resistance value is about 23Ω, the running winding resistance value is about 10Ω, the normal resistance value of the starting and running series windings should be the sum of the two.

2, the motor speed is slow and weak. When the speed of the motor is slow and powerless after being energized, for capacitor-started motors, the capacitor capacity is insufficient, the leakage is serious, or the power supply voltage is too low. In addition, if the aluminum rod part of the squirrel cage is seriously damaged and broken, especially the motor Frequent start and alternate rotation of forward and reverse, the large induced current of the rotor aluminum bar is easy to break the rotor aluminum bar, which also causes the slow and weak operation. When a crack is found in the aluminum strip, a small hole can be drilled between the cracks with a hand drill, the corresponding aluminum wire strip is embedded in the hole, then it is knocked flat and riveted, and finally polished with a steel file and sandpaper to be smooth. If the fracture surface of the aluminum bar is large, it can be repaired by the method of aluminum wire gas welding.

3. The motor housing is charged. Generally, the motor leakage current should not be greater than 0.8mA to ensure personal safety. The main reason for the leakage of the motor casing is that the insulation of a lead wire in the motor is damaged and touches the casing; the motor winding is partially burned, causing leakage between the stator and the casing. It is more common to be in a high-humidity environment for a long time, which causes the motor to be dampened and the insulation is reduced, which causes the chassis to be charged. At this time, you can use a shaking table to measure the insulation resistance between the windings of the motor and the casing. If it is less than 2MΩ, it means that the motor has been seriously wet. The stator windings of the motor should be baked and dehumidified.

4. The temperature rise increases when the motor is running. Under normal working conditions of various household single-phase motors, the surface temperature of the motor casing is generally about 20 ° C higher than the ambient temperature, and the highest temperature rise should not be higher than 70 ° C. If the surface temperature of the housing rises sharply after a few minutes of operation, and the machine emits tar or even smoke, it is an overheating fault of the motor. The reasons for the motor overheating and temperature rise are mainly the quality of the motor itself; the motor has been in an overloaded state for a long time (the motor load caused by the failure of the transmission mechanism); the heat dissipation condition of the motor is poor; and the motor winding is locally short-circuited. The more common one is the winding short-to-turn short circuit, which can be removed to check the winding. If the wire package is not burned, the stator can be dipped and insulated again, and then dried. If the wire package is partially burned, only the winding wire package must be replaced.

5. The motor runs loudly. There are two main reasons for motor working noise. One is mechanical noise, which is mainly due to motor bearing wear and oil shortage, resulting in hard friction noise. For this, add grease after cleaning to reduce noise. When the rotor shaft and bearing are loose or the end cover is loose, the motor will also generate axial movement and make noise when it is rotating. There are also some motors with poor assembly quality, the bearing chamber is not concentric, and the radial clearance of the motor is uneven. In this regard, as long as the outer cover and the rear inner cover are removed, the rotor and the stator base are taken out, and the central shaft of the inner cover is rapped again, emergency repair can be performed.