| 摘要 |
A heating cable for use and for example a heating blanket. The heating cable comprises first (1) and second conductors (5) which extend along the length of the cable and which are separated by a separation layer (4). The conductors and separation layer may be coaxial. The first and second conductors are connected at one end of the cable in series such that if the first and second conductors are connected at the other end of the cable to respective poles of a power supply equal currents flow in opposite directions through adjacent portions of the conductors. This substantially eliminates electromagnetic radiation being emitted from the cable. The first conductor has a positive temperature characteristic and the separation layer has either a negative temperature characteristic or melts at a predetermined threshold temperature. The power supplied to the cable may be modulated in response to variations in the end to end resistance of the positive temperature co- efficient conductor. The power supplied to the cable may be terminated in the event of current flowing through the separation layer exceeding a predetermined threshold.
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