| 摘要 |
<p>A varistor MOV is connected across a power supply LN to protect equipment connected at AB against voltage spikes. Leakage current through the varistor is monitored by a thermal sensor 20 and microchip 12, which also receives input from an ambient temperature sensor 22 remote from the varistor. When the difference between the sensed temperatures exceeds a predetermined operating level, before dangerous overheating of the varistor occurs, the microchip signals a warning condition by illumination of LED 14 and/or operation of a tone generator 16. The user is thus given a warning that the device is ageing and will shortly need replacing, whilst the protected equipment remains fully operational. <IMAGE></p> |
