| 摘要 |
A heating cable comprising a first and second power conductor 21,22 and a failure detector 24 extending along the length of the cable and a heating element body 23. The failure detector comprising a conductor 25 surrounded by an electrically insulating sheath 26 of lower melting point than the element material, the failure detector being located such that it is generally between the first and second conductors, the first and second conductors being in electrical connection with each other via the heating element body. The detector 24 is connected to a control module 29 to interrupt the power supplied from unit 28 in the event of a failure in the cable e.g. a wet fire causing current to flow or a resistance change in the failure detector when localised excessive heat caused by a fault melts the sheath 26. The conductor 25 may be a wire, a foil or an apertured foil and may be alternatively positioned closer to one of the power conductor or close to the protective sheathing 27. The heating element body may be a PTC material, a NTC material or a combination of these. Conductors 21,22 may also comprise foils. |
