Patent ID: 6483681
Filing Date: 2002-11-19
Classification: H02H

Abstract:
A residual current device, comprising:an amplifier circuit producing a fault voltage derived from a fault current; a comparison circuit comparing the fault voltage with a reference voltage; a power supply unit; a reference circuit coupled to the power supply unit producing an operating voltage for the amplifier circuit and the reference voltage, the reference circuit including an arrangement that raises the reference voltage to at least an instantaneous operating voltage if an output voltage of the power supply unit falls below a predetermined value and if the fault voltage is less than the reference voltage; a first voltage divider coupled to the operating voltage and producing the reference voltage, the first voltage divider further being coupled to ground via a controllable switching element, the switching element being controlled as a function of an output voltage of the power supply unit; a second voltage divider producing a control voltage for the controllable switching element; and a feedback circuit, an output of the comparison circuit being connected to the reference circuit via the feedback circuit, wherein the feedback circuit includes a diode and a resister connected in series, the feedback circuit being connected to a control line that carries the control voltage.