Patent ID: 8593838
Filing Date: 2013-11-26
Classification: H02H

Abstract:
1. Power supply device for intrinsically safe power supply of an intrinsically safe load circuit, comprising: a voltage source; a power-limiting circuit comprising at least two controllable semiconductor devices; a current-limiting circuit comprising at least one resistor; a load circuit connector connected to the load circuit; and a current-measuring means is provided for measuring a load current taken from the load circuit connector, wherein the power-limiting circuit and the current-limiting circuit are active between the voltage source and the load circuit connector, wherein the resistor has a resistance value that suffices to limit a short circuit current to a current without danger of a spark ignition, and wherein the current-measuring means also comprises at least one operation amplifier which is switched as a difference amplifier, the at least one operation amplifier having an input connected to said resistor such that a voltage drop across the resistor acts as an input signal therefor, and an output adapted to produce an output signal acting as a measure of the load current.