| 摘要 |
<p>A voltage drop develops across a current-limiting resistor 14 connected between a power source 10 and a load 16 in proportion to the current draw. A zener diode 18 becomes conductive in the reverse direction when the voltage drop increases to a threshold, thereby turning on a light emitting diode 22 (LED), to detect excessive current draw. A photo-SCR may be optically coupled to the LED to provide a latched fault indication. For detecting partial or complete open loads, normal load current will be high enough for LED 22 to be on, and to turn off as current falls. A thermistor may be substituted for the current limiting resistor in certain cases to provide protection and detection at higher current demand levels. <IMAGE></p> |
