(1) the capacitor Banks should adopt appropriate protective measures, such as the balancing differential relay protection or using instantaneous over-current relay protection, for more than 3.15 kV capacitor, a separate device must be on each capacitor fuse, fuse rated current should be according to the characteristics of fuse and plug flow to selected, when the general is 1.5 times the rated current of the capacitor is appropriate, in order to prevent the capacitor tank explosion.(2) in addition to the above points out that the protection of the form, if necessary, you can also make the following several kinds of protection: 1) if the voltage is often and for a long period of time, needs to take measures to make the voltage rise no more than 1.1 times rated voltage. 2) with the appropriate current automatic switch, the current rise no more than 1.3 times the rated current. 3) if the capacitor with overhead lines connecting, available suitable arrester for atmospheric overvoltage protection.
4) in the high voltage network, more than 20, when a short circuit current and short circuit current protection device or fuse cannot reliably protect of short circuit, the single phase short circuit protection should be adopted.
(3) the correct selection of the protection of the capacitor Banks, is the key to ensure safe and reliable operation of the capacitor, but either way, protection shall meet the following requirements: 1) protection devices should be sensitive enough, regardless of capacitor Banks in a single capacitor the malfunction of the internal part or component is damaged, can reliably protection device. 2) can selectively remove fault capacitor, or all power after disconnecting the capacitor group, easy to check out the damaged capacitor. 3) in the process of the capacitor stop sending and power system grounding or other failure occurs, wrong protection device. 4) protection should be easy to install, adjust, test and operation maintenance. 5) consume less power, lower operating cost.
(4) the capacitor is not allowed to furnish automatic reclosing device, instead should be installed without pressure release automatic tripping device.Is mainly due to the need of capacitor discharge time, when the switch of capacitor group trip, if reclosing immediately, is too late to discharge the capacitor, the capacitor may in some feelings and reclosing voltage polarity opposite electric charge, it will make the closing moment produces huge impact current, resulting in capacitor shell expansion, fuel injection, and even explode.
Dingfeng capacitor -- Preservation of the Power Capacitor