Views: 0 Author: Site Editor Publish Time: 2020-03-11 Origin: Site
1. Install overload protection in each group circuit
Because the overcurrent protection is set according to the full input of the 4 groups of capacitors, the reaction to the overcurrent phenomenon caused by the harmonic current amplification of the group is slow or even does not respond. Therefore, overload protection is installed in each group circuit. Because of the AC contactor, it can only be opened. Break the load current under normal conditions, can not open the fault current, replace the AC contactor with a ZN-28 vacuum circuit breaker. When the harmonic content is high, it acts on the trip to prevent harmonics from damaging the capacitor and the internal fuse. .
2. Install open triangle voltage protection in each group circuit
When the fuse in one phase of a capacitor is blown, the capacitive reactance changes, which is not equal to the other two compatible reactances, causing a voltage imbalance between the faulty phase and the sound phase. Therefore, a low-setting voltage relay is installed at the opening triangle of the secondary winding of each group circuit voltage transformer. When the fuse in one phase is blown, an unbalanced voltage appears at the opening triangle and an alarm signal is issued. The device can accurately reflect the internal failure of the capacitor, and it is not affected by the system ground and the unbalanced voltage of the system, and the injured capacitor can be taken out of operation in time.
3. Periodic measurement of capacitance
In view of the difficulty of capacitance measurement, advanced measurement equipment was purchased, and the capacitor bank was regularly measured using a fully automatic capacitor bridge. The capacitance of a single capacitor does not need to be disconnected, and the measurement is simple, fast, accurate and reliable. Maintenance personnel regularly conduct capacitance measurement. When the fuse in one phase of a capacitor is blown, the capacitance will change. When the measured capacitance decreases, exceeding 3, the injured capacitor will be taken out of operation in time.
Negligence in design and maintenance may bring hidden dangers to the safe operation of capacitors. Therefore, only with well-configured protection and regular measurement of capacitance to prevent micro-duration can we reduce or even avoid the expansion of capacitor accidents, increase the availability of capacitors and extend the use of capacitors life.
