How to test the generator by yourself?

When the motor runs or fails, four methods can be used to prevent and eliminate the failure in time to ensure the safe operation of the motor.

Look at it first

Observe whether there is any abnormality during the operation of the motor, which is mainly manifested in the following situations.

1. When the stator winding is short-circuited, you may see the motor smoking.

2. When the motor is seriously overloaded or out of phase, the speed will slow down and a heavy "buzzing" sound will be made.

3. The motor maintenance network is running normally, but when it suddenly stops, you will see sparks at the loose connections; Fuse blown or component stuck.

4. If the motor vibrates violently, it may be that the transmission device is stuck or the motor is poorly fixed, and the anchor bolt is loose.

5. If there are discoloration, burning marks and smoke marks at the contact points and joints in the motor, it means that there may be local overheating, poor contact or winding burning at the conductor joints.

Second, listen.

When the motor is running normally, it should make a uniform and slight "buzzing" sound, without noise and special sound. If the noise is too loud, it includes electromagnetic noise, bearing noise, ventilation noise, mechanical friction noise, etc. It may be a fault precursor or a fault phenomenon.

1. For electromagnetic noise, if the motor makes a heavy sound, there may be the following reasons.

(1) The air gap between stator and rotor is uneven. At this time, the sound is high and low, and the interval between the high and low notes remains unchanged. This is due to bearing wear, which leads to the misalignment of stator and rotor.

(2) The three-phase current is unbalanced. This is the reason for the wrong grounding, short circuit or poor contact of the three-phase winding. If the sound is dull, it means that the motor is seriously overloaded or out of phase.

③ Loose iron core. When the motor is running, the iron core fixing bolt becomes loose due to vibration, which causes the iron core silicon steel sheet to become loose and make noise.

2. For bearing noise, it should be monitored frequently during motor operation. The monitoring method is: put one end of the screwdriver against the bearing installation part, and the other end is close to the ear to listen to the running sound of the bearing. If the bearing runs normally, its sound is a continuous and small "rustling" sound, and there will be no ups and downs and metal rubbing sound. If the following sounds appear, it is an exception.

(1) There is a "squeak" sound when the bearing is running. This is a kind of metal rubbing sound, which is generally caused by the lack of oil in bearings. The bearing should be removed and an appropriate amount of grease should be injected.

(2) If there is a "squeaking" sound, it is the sound made when the ball rotates, which is usually caused by dry grease or lack of oil. Appropriate amount of grease can be added.

(3) If there is a "click" sound or a "crunch" sound, it is caused by the irregular movement of the ball in the bearing, which is caused by the damage of the ball in the bearing or the long-term non-use of the motor and the drying of grease.

3. If the transmission mechanism and the driven mechanism make continuous sounds instead of high and low sounds, it can be handled as follows.

(1) Periodic "snapping" sound, which is caused by uneven belt joints.

(2) Looseness between coupling or pulley and shaft and wear of key or keyway lead to periodic "knocking" sound.

(3) The blade collides with the fan cover to produce uneven collision sound.

Third, the smell

You can also judge and prevent faults by smelling the motor. Open the junction box and smell it with your nose. See if it smells of burning. If there is a special paint smell, it means that the internal temperature of the motor is too high. If there is a heavy burning smell or burning smell, it may be that the insulation maintenance network has been broken down or the winding has been burned. If there is no smell, the insulation resistance between the winding and the shell needs to be measured by megger, which is less than 0.5 trillion and needs to be dried. The resistance value is zero, indicating that it has been damaged.

Fourth, touch

Touching the temperature of some parts of the motor can also determine the cause of the fault. To ensure safety, you should touch the parts around the motor housing and bearing with the back of your hand. If the temperature is abnormal, the reasons may be as follows.

1. Poor ventilation. For example, the fan falls off and the ventilation pipe is blocked.

2. overload. Resulting in excessive current and overheating of the stator winding.

3. Turn-to-turn short circuit of stator winding or unbalanced three-phase current.

4. Frequent starting or braking.

5. If the temperature around the bearing is too high, it may be caused by bearing damage or oil shortage.