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What are the reasons for the unstable AC motor speed?
Jul 24, 2018

What are the reasons for the unstable AC motor speed? From the principle analysis, the following situations are possible:

First, the adjustable resistance is poorly contacted. Because the adjustable resistor is mounted on the control panel, the use frequency is very high, and the use time is long. The situation of poor contact is common.

Second, there is toner between the rotor of the AC motor and the commutator, or the quality of the carbon brush itself is not good.

Third, measuring the other three diodes is also normal, but in the comparison measurement, it is found that the positive and negative polarities of the two types of diodes are completely opposite, so it is necessary to pay attention to the best use of the same type of the same specification.

If the AC motor speed is unstable, it is probably the above reason.

The concept of motor overload: general motor has a certain operating power, called rated power, in watts (W), if in some cases the actual power of the motor exceeds the rated power of the motor, then this is called The phenomenon is that the motor is overloaded.

The mechanical equipment is running. How do we judge whether the motor is overloaded? What are the symptoms? Taizhou Hengfu Motor Factory will discuss with you.

Motor overload mainly has the following symptoms:

1. The motor generates heat increase;

2. The motor has a low-pitched sound and the vibration is normal;

3. The motor speed drops, and may even drop to zero;

4. If the load changes drastically, the motor speed will rise and fall;

The main reasons for motor overload are:

1. Electrical reasons:

1.1, the motor voltage is too high or too low;

1.2, the motor is seriously damp or corrosive gas corrosion for a long time, so that the insulation resistance decreases;

1.3: The winding connection method does not meet the requirements. The original Y-connected winding is mistaken for △ coupling during maintenance.

2. Mechanical reasons: such as excessive torque, motor damage (bearing vibration), etc.;

2.1: The load is too heavy;

2.2: The motor bearing is out of oil, dry grinding or the rotor machinery is not concentric, so that the motor current exceeds the rated value;

2.3: The mechanical transmission part is faulty.

3. Improper selection, long starting time, etc., should have used the brake motor, the speed motor has only used ordinary three-phase asynchronous motor.

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