Monitoring device for wide-dynamic-range currents, in particular for monitoring traction currents

A monitoring apparatus for wide-dynamic-range currents, comprising:

• a supply line (204) carrying a current (Idrive) to be monitored;
• a shunt resistor (203) in the supply line (204);
• a measurement amplifier circuit (217),
• wherein an input side of the measurement amplifier circuit (217) receives a voltage drop (Uin) across the shunt resistor (203), and
• wherein an overall dynamic range of the measurement amplifier circuit (217) covers normal-operation currents and fault currents;
• and
• an evaluation device that receives an output signal (IM) of the measurement amplifier circuit (217), to record the normal-operation currents and the fault currents,
• wherein the measurement amplifier circuit (217) is a single-channel measurement amplifier circuit (217), comprising
• a measurement amplifier (502) that reproduces an overall dynamic range of the voltage drop (Uin) across the shunt resistor (203), and
• a compression stage (503),
• wherein the compression stage (503) receives an output signal of the measurement amplifier (502),
• wherein the compression stage (503) has at least two different transfer functions (tf401, tf402),
• wherein a first transfer function (tf401) of the at least two different transfer functions (tf401, tf402) converts a measurement range of the normal-operation currents at high resolution, and
• wherein a second transfer function (tf402) of the at least two different transfer functions (tf401, tf402) compresses the dynamic range of the voltage drop across the shunt resistor (203) and converts a measurement range of the fault currents into the output signal (IM) of the measurement amplifier circuit (217) at lower resolution than the first transfer function (tf401).