| 摘要 |
<p>A self limiting electrical heater comprising an elongate resistance heating element (4) and a PTC resistor (5). The resistor is elongate and extends along the length of the heating element so as to be responsive to the temperature of the entire length of the heating element. The heating element (4) and resistor (5) are connected in series, the resistor having a positive temperature coefficient such that its electrical resistance is substantially less than that of the heating element when at a normal operating temperature but increases rapidly when exposed to temperatures above the normal operating temperature.</p> |
