Analysis of common problems of AC power supply and solutions

Ac power supply is mainly composed of main loop, power loop, IM drive and protection loop, cooling fan and other parts. Its structural form is unitary or modular. Improper use of the AC power supply or improper setting environment may lead to misoperation and failure of the AC power supply. Today, I would like to share with you the common problems and solutions of AC power supply.

500kw load bank
500kw load bank
1. The main loop is faulty
The main circuit is mainly composed of three-phase or single-phase rectifier bridge, smooth capacitor and wave capacitor. IPM should consider the appropriate ambient temperature, and measures can be taken to reduce the pulsating current. Using ac and DC reactors with higher power factor can reduce the pulsating current and prolong the service life of electrolytic capacitors.
In the process of capacitor maintenance, the deterioration degree of electrolytic capacitor is usually judged by measuring the electrostatic capacity. If the electrostatic capacity is less than 80% of the rated value and the absolute impedance is less than 5 MEgohms, the capacitor needs to be replaced.
2. Cooling system failure
The cooling system mainly includes heat sink and cooling fan. When the service life of the cooling fan is short, it will vibrate. If the vibration is too large, the fan will stop running, and the IPM of the AC power supply will trip because of the high temperature. The service life of the fan is closely related to the bearing, about 10000 ~ 35000h. If the AC power supply continues to run, generally replace the fan or bearing every two to three years.
3. external electromagnetic induction interference
If there are interference sources in the AC power supply environment, they enter the power supply through the power cable and cause misoperation of the control loop. As a result, the POWER supply cannot work properly or even the AC power supply may be damaged. Methods to reduce interference include: installing anti-voltage absorption devices on the relays and contactor wires around the AC power supply, installing radio noise wave devices on the input end of the AC power supply to reduce input high harmonics, etc.