| CPC G01R 31/14 (2013.01) [G01R 13/02 (2013.01); G01R 19/0023 (2013.01); G01R 19/0053 (2013.01); G01R 19/252 (2013.01); G01R 27/16 (2013.01)] | 14 Claims |

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1. An insulation monitoring device comprising:
an impedance formed between a power line and a ground of a system, the impedance comprising:
a signal generation circuit for applying a triangular wave signal to the power line through a signal measurement circuit;
the signal measurement circuit for measuring a voltage difference across a detection resistor of the signal measurement circuit or a current flowing through the detection resistor when the triangular wave signal is applied to the impedance;
a control circuit configured to obtain an impedance value of the impedance based on at least one of the voltage difference and the current and to monitor the impedance value
wherein the impedance includes an insulation resistor and a capacitor, and
wherein the control circuit is further configured to:
obtain a voltage difference across both ends of the insulation resistor based on a voltage difference across both ends of the detection resistor;
obtain the insulation resistor value by obtaining the ratio of the difference in voltage across the insulation resistor between the first time point t1 and the second time point t2 and the difference in current flowing through the detection resistor;
obtain the capacitor value based on the insulation resistor value at the second time point t2.
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