Maintenance and operation management of power capacitor

Power capacitor is a kind of static reactive power compensation equipment. Its main function is to provide reactive power to power system and improve power factor. Some problems in the maintenance and operation management of power capacitors are summarized as follows:

1、 Proper protection measures shall be taken for the protection capacitor bank of power capacitor

If balance or differential relay protection or instantaneous over-current relay protection is adopted, for capacitors of 3.15 kV and above, a separate fuse shall be installed on each capacitor. The rated current of the fuse shall be selected according to the characteristics of fuse and inrush current when connecting, generally 1.5 times of the rated current of capacitor is appropriate to prevent explosion of capacitor tank.

2、 On and off of power capacitor

1. The discharge network of power capacitor bank shall be checked by megger before connection.

2. When connecting and disconnecting the capacitor bank, the following points shall be considered:

(1) When the voltage on the bus bar (bus) exceeds 1.1 times of the allowable rated voltage, it is forbidden to connect the capacitor bank to the power grid.

(2) The capacitor bank shall not be re connected within 1 min after it is disconnected from the power grid, except for automatic re connection.

3、 Discharge of power capacitor

1. The capacitor should discharge automatically every time it is disconnected from the power grid. No matter what the rated voltage of the capacitor is, the terminal voltage should not exceed 65 V after the capacitor is disconnected from the grid for 30 s.

2. In order to protect the capacitor bank, the automatic discharge device should be installed on the load side of the circuit breaker of the capacitor, and it is often directly connected with the capacitor. When bulb is used, the number of bulbs should be increased appropriately in order to prolong the service life of the bulb.

4、 Safety precautions for handling faulty capacitors

To deal with the fault capacitor, the circuit breaker of the capacitor shall be disconnected, the isolating switch of both circuit breakers shall be opened, and the capacitor bank shall be discharged by discharge resistance. When discharging, first connect the grounding end of the grounding wire, and then discharge the capacitor with the grounding rod for many times until there is no discharge spark and discharge sound, and then fix the grounding end. The two poles are short circuited, and then they are removed and replaced.