CAPACITOR STORAGE UNIT

The CSU provides a reliable cost effective solution to maintaining electrical system safety and may be used as a backup for battery powered trip units. It is an ideal solution for switchgear in remote locations where maintenance free operation is required.

Switching Systems developed a Capacitor Storage Unit (CSU) to supply power for the breaker trip coil and electronic sensing relay(s). Capacitors are used for energy storage so no maintenance is required.

To overcome this problem battery powered tripping units are used. However this approach introduced a maintenance problem where batteries had to be checked and replaced at regular intervals. Poor battery maintenance resulted in the protective devices becoming inoperative and as a result compromising system safety.

Electrical reticulation systems always employ circuit breakers on the incoming supply so that in the event of a fault in the consumers plant the supply can be quickly disconnected regardless of the high fault currents that may be present. Breakers used in MV Switchgear employ a shunt trip coil to trigger the breaker disconnect mechanism. In addition to the breakers the MV Switchgear will incorporate protection relays to detect fault conditions such as over current or short circuits. Modern electronic protection devices require auxiliary power in order to operate. If battery tripping is not used and power is supplied from the VT then when a fault occurs the supply voltage can drop to a level where the protective devices cannot operate and it is impossible to disconnect automatically.