FUSE FAILURE DISPLAY
The invention relates to a circuit for displaying a fuse failure for a fuse (1) trip status monitoring system. A lighting diode (2) is provided in order to display the trip status of the fuse (1), said lighting diode being arranged in a current path parallel to the circuit (1). When the fuse (1) is not tripped, the parallel current path has such a high resistance compared to the resistance across the fuse (1) that the current across said current path is not sufficient to actuate the lighting diode (2), and when the fuse (1) is tripped, the parallel current path has such a low resistance compared to the resistance across the fuse (1) that the current across said current path is sufficient to actuate the lighting diode (2). Furthermore, a current-limiting device for limiting the current across the lighting diode (2) and a voltage-limiting device for limiting the voltage across the tripped fuse (1) are provided. It is essential to the invention that a field-effect transistor (3) and a resistor (4) are provided in series in order to achieve the high resistance of the parallel current path when the fuse (1) is not tripped, and the same resistor (4) is provided for arranging the current-limiting device in the parallel current path when the fuse (1) is tripped in order to form a control voltage for the field-effect transistor (3) in the parallel current path with the lighting diode (2), the blocked state of the field-effect transistor (3) depending on said control voltage. Thus, a universal and inexpensive circuit is provided for monitoring fuses, said circuit being suitable for direct current operations as well as for alternating current operations.