How to choose the shunt capacitor bank protection correctly?

It should be known that the correct choice of shunt capacitor bank protection mode is the primary premise to ensure the reliable operation of the capacitor bank, then how to choose the right protection mode for the capacitor bank?

What are the protection methods of shunt capacitors in power system?

Series reactor

Each phase capacitor bank is connected with a reactor, which can effectively resist harmonics in the distribution system, inhibit inrush current, and ensure the safe and stable operation of the capacitor.

Overcurrent protection

System imbalance is easy to lead to a single capacitor or capacitor bank of a phase capacitor on the over-current, and then prone to wiring failure or inter-line failure. Overcurrent protection device can effectively avoid the occurrence of related accidents.

Fuse protection

Add fuse protection. Fuses are the first line of defense for capacitor bank overcurrent protection. They can proactively cut off and isolate faulty components under abnormal conditions to ensure the normal operation of other intact components.

Overvoltage protection

Partial discharge and partial heating occur in capacitors operating for a long time under high voltage. The installation of overvoltage protection device can ensure that the capacitor does not exceed the maximum allowable voltage operation, to avoid operating accidents.

The shunt capacitor banks shall meet the following requirements:

1. The protective device installed should be sensitive enough to deal with emergencies in time.

2. When the failure of the capacitor may endanger the normal operation of the system, the protection device should be timely off; If the capacitor bank is not in normal operation, the protection device should send a signal to remind.

3. The protection device should be able to selectively remove the faulty capacitor to ensure the reliable operation of the rest of the system. Or after disconnecting all the power supply, it is convenient to check and replace the damaged capacitor.

4. The protective device selected should be easy to install, and maintenance and overhaul should not be too tedious.

5. When grounding or other faults occur in the power system or capacitor operation, ensure that the protection device does not misoperate.

6. It is forbidden to install automatic reclosing device for the capacitor, because the capacitor will still retain a large amount of charge after power failure and it will take a certain amount of time to discharge. If the capacitor is re-closed immediately, it is easy to produce huge shock current, which will cause serious consequences such as capacitor explosion.