Knkong Electric Co.,Ltd

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What regulations should the protection device of the parallel compensation capacitor bank meet?

The parallel compensation capacitor bank shall be installed with protection devices according to the following provisions:
1) The short circuit of the connecting line between the capacitor bank and the circuit breaker can be equipped with short-term current quick-break and overcurrent protection, which acts on tripping. The operating current of the quick-break protection should be in the minimum operation mode when the two-phase short circuit of the end lead of the capacitor has a sufficient sensitivity coefficient setting. The operating current of the overcurrent protection device should be set according to the maximum working current allowed to bypass the capacitor bank for a long time. 

2) For the internal fault of the capacitor and the short circuit of the lead wire, it is advisable to install a special fuse for each capacitor. The rated current of the fuse can be 1.5-2.0 times the rated current of the capacitor. 

3) When the number of faulty capacitors in the capacitor bank is cut to a certain number, causing the capacitor terminal voltage to exceed 110% of the rated voltage, the protection should disconnect the entire group of capacitors. For capacitor banks with different wiring, one of the following protections can be used:
a. Single star-connected capacitor banks can adopt a neutral line to ground voltage unbalance protection. Three-phase transformer price
b. Multi-segment series single-star connection capacitor bank can also use inter-segment voltage differential or bridge differential current protection.
c. Double-star-connected capacitor banks can be protected by neutral unbalanced voltage or unbalanced current.

4) The single-phase ground fault of the capacitor bank can be detected by the insulation monitoring device on the bus connected to the capacitor bank.

5) Over-voltage protection should be installed for the over-voltage of the capacitor bank, and it will act on the signal or trip with a time limit.

6) Low voltage protection should be installed for the busbar loss of pressure, and it can act on the signal or trip with a time limit.

Knkong Electric

Date:2019-07-04 08:45

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