| 摘要 |
<p>A single or multi-pole electric circuit breaker has, associated with the busbar (1) of the or each pole, a thin film sensor (2) electrically insulated and spaced a predetermined fixed distance from a surface of the busbar (1). The thin film sensor (2) detects the magnetic field around the busbar to give an indication of the current passing therethrough. Signals from the thin film sensor (2) are interpreted by a microprocesor (3) which effects operation of a tripping mechanism (7), tripping the circuit breaker, if the signals fulfil preprogrammed tripping criteria. The thin film sensor may be encapsulated in a moulded body (8) of electrically insulating plastics material. The moulded body (8) may itself be mounted on or in a spacer member such as a sleeve (13) to locate the thin film sensor (2) at a predetermined spacing from its associated busbar.</p> |
