| 摘要 |
A switch can be connected in parallel to a fuse holder 1, and closed in response to a state of a mains supply which the fuses protects, enabling the fuse to be placed in the fuse holder without being affected by magnetic inrush current. The switch may have an auxiliary fuse in series and close at a time when the supply is near a maximum of its voltage waveform. Should a fault condition at fundamental mains frequency be detected the switch can be opened. The circuit is removable and may include a removable current transformer which can be located over a supply conductor. The circuit can be used for the 650 volt AC railway signalling supply and allows a fuse to be replaced without it blowing due to magnetic inrush currents from transformers. |
