2.7V 3.3F farad capacitor
For variable / substation DC systems
In China's 35kV substation and 10kV switch station (room) built in the 1960s and 1980s, the operating mechanism of most high-voltage switches (circuit breakers) is the CDX-type electromagnetic operating mechanism. A corresponding DC system is provided in the power distribution room of the substation or substation for use as a DC power supply for switching operation, control and protection. These DC power supply devices are mainly capacitor-storage silicon rectification switching devices and DC screens partially composed of batteries.
Capacitor energy storage silicon rectification switching device has been widely used at that time due to its simple structure, low cost and low maintenance. However, there is a fatal defect in actual use: the reliability of accidental closing is poor. The reason is that the capacity of electrolytic capacitors for energy storage is limited (only a few thousand μF), and the leakage current is large .
Although the DC screen composed of batteries can store a large amount of electric energy, it becomes a necessary device in some important transformers and substations, but because of its high operating cost and short service life, these devices can only be used for 110kV level. The substation is difficult to promote.
Supercapacitors have made it possible to solve the above problems due to their long life, frequent and rapid charge and discharge characteristics, and low price. If two 0.85F, 240/280V supercapacitors are connected in parallel, they can completely replace the bulky, frequently maintained, and polluted battery packs. Since the energy consumption of a closing switch is only 3% of the energy stored in the supercapacitor (70kJ), this energy can be quickly replenished in the floating charging circuit, so it is fully adapted to continuous frequent operation and has a pole. High reliability.