| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a current measurement device with no variation in characteristics due to temperature change. SOLUTION: A current measurement device comprises a resistor 2 connected, in series, to a current path 1 where a current Ia flows, a transformer 3 where an input coil 4 is connected between both ends of the resistor 2, a magnetic detecting means 6 for detecting a magnetic fluxϕa generated at a core 3a of the transformer 3, a compensating coil 5 wound around the core 3a, a magnetic balance circuit 7 wherein a compensating Ib is allowed to flow the compensating coil 5 according to the detecting result of the magnetic detecting means 6 so that such magnetic fluxϕb as cancel the change of the magnetic fluxϕa is generated, and a current detecting circuit 8 which detects the compensating current Ib and then detects the current Ia based on the compensating current Ib. The temperature change amounts occurring at the resistor 2 and the input coil 4 at electrification are different. The resistor 2 and the input coil 4 are formed from the metal materials different from each other in resistance temperature coefficient so that the rates of resistance change at the resistor 2 and the input coil 4 under temperature change are almost equal.</p> |
