1. When starting, the power supply voltage drops too much, the starting is slow or even unable to start. For long axis motors, the starting torque is proportional to the square of the voltage. The voltage and starting torque are reduced by 10% and 20%, respectively.

2. In operation, when the voltage is low and the load is constant, the speed will drop (or even stop), the current of the long axis motor will increase, the motor will overheat, affect the service life, and even burn out. Voltage distortion: voltage waveform deviates from normal sine wave. Common waveform spike, voltage appears electrical noise interference.

3. Voltage waveform spike refers to the short-time impulse beyond the normal voltage. Low energy small spike mainly comes from the switch of inductive load, which is a common phenomenon in factories. The larger peak is mainly caused by the transmission of flashover discharge on the power line. The duration is very short, and the peak value can reach 5 ~ 10 times of the normal voltage. It may make the data stored in the control device lose or cause misoperation, and it may also cause immediate damage to the equipment or even random damage which is difficult to find.

4. Electrical noise (a common form of power disturbance at present, which may be easier to correct. However, it is difficult to detect it. Low amplitude voltage spikes will cause electrical noise interference. The emission of radio waves, computers, business machines and even the poor contact of electrical connections will produce electrical noise. It will cause the computer misoperation, and the electromagnetic interaction between the components of the control equipment may produce enough electrical noise, which will lead to the operation error. Although most of the equipments are equipped with filters, we should avoid working in the environment with serious electrical noise.

5. Short time interruption of power supply only 5ms short time complete interruption may stop the work of some sensitive electrical equipment. For the user, the trouble is that the data stored in the control device is lost or it takes time to reprogram.