Development of a fault current limiter for 22 kV distribution system

A fault current limiter (FCL) for 22 kV distribution systems has been developed in order to improve the reliability, cost effectiveness and safety of power distribution systems by limiting the short-circuit current. When a short circuit occurs in the distribution system, a fault current over ten times the normal load current flows towards distribution lines. This FCL rapidly opens the contact by applying the electromagnetic force of the fault current before the substation circuit breakers trip, and limits the fault current. The FCL has a simple structure with a commutating unit and a resistor unit to limit fault current, a disconnecting switch to interrupt power, and a control unit. The commutating unit is activated by the electromagnetic force of the fault current. Compactness, cost reductions, and repeated usage can be achieved by using this device, enabling the device to be mounted on the poles. Various demonstration tests of the FCL have proved that the current limiting performance is satisfactory for practical use.