| 摘要 |
<p>An immersible heater has a protective casing (2) divided internally into two compartments by a barrier (5). A first of the compartments (3) contains a printed circuit board (6) and a first thermistor (15) arranged to sense substantially the temperature of a medium in which the heater is immersed whilst the second compartment contains an electric heating element (10) and a second thermistor (16) arranged to sense substantially the temperature of the casing adjacent the heater. The supply of power to the heating element is controlled by the printed circuit board (6) in dependence upon the responses of the thermistors. <IMAGE></p> |
