摘要 |
A circuit interruption device (10) comprises:
a main branch (12);
a secondary branch (14) having an electrical on-resistance which is higher than an electrical on-resistance of the main branch (12); and
first and second terminals (16,18) for connection, in use, to an electrical network (20), the main and secondary branches (12,14) extending between the first and second terminals (16,18);
wherein the main branch (12) includes a switching apparatus (22) which is switchable to selectively allow current to flow in the main branch (12) in a normal mode of operation or commutate current from the main branch (12) to the secondary branch (14) in a fault mode of operation, and the secondary branch (14) includes at least one switching device (26), the or each switching device including at least one normally-on switching element, the secondary branch (14) further including a control unit in communication with the or each normally-on switching element, the secondary branch (14) further including a power extraction circuit which is electrically coupled with the control unit,
wherein during the normal mode of operation the or each normally-on switching element is in an on-state to permit the secondary branch (14) to conduct current, and during the fault mode of operation the control unit controls the switching of the or each normally-on switching element to an off-state to inhibit current flow in the secondary branch (14),
wherein the power extraction circuit extracts power from current flowing in the secondary branch (14) to drive the control unit. |