| 摘要 |
<p>A protective circuit arrangement for an electrically heated blanket, or pad includes a heater element formed as a coaxial cable, a rectifier and a fuse. The heater cable consists of an inner conductor formed from a layer of resistance wire wound a round a core of insulating material, a layer of insulation formed by a thermoplastic material, an outer layer of resistance wire wound around the layer of insulation and an outer insulating sheath. The rectifier is connected across the ends of the cable conductors remote from the input from a source of supply, the circuit being such that the two layers of resistance wire, the rectifier, the fuse and the supply are all connected in series. In the event of overheating of the cable at any point the thermoplastic insulation will break down shorting out the rectifier and at least doubling the load on the fuse causing it to blow.</p> |
