Circuit for transmitting a measurement current from an intrinsically safe sensor to a non-intrinsically safe area

摘要

This circuit arrangement comprises a transformer (2) for transmitting a measurement current (I), which is output by a sensor arrangement (1) at a measurement location situated in an intrinsically safe area (10), to a non-intrinsically safe area (20), in which a current measuring resistor (5) is situated. A DC converter (3) serves for the power supply of the sensor arrangement. A transformer (2) belongs to the DC converter (3), has a primary winding, which faces the non- intrinsically safe area, two identical partial windings (21, 22) connected in series in the same sense, and a single secondary winding (23) , which faces the intrinsically safe area. A first end of the current measuring resistor (5) is connected to a circuit zero-point (SN) and a second end to a center tap of an output stage (31) of the DC converter (3) . The center tap is connected to the input of an offset adjusting stage (6), an output of which is connected to the input of a voltage/current converter (7). A power source (4) is connected to the junction point of the partial windings (21, 22) and to the circuit zero- point.