A method and system for monitoring electrical isolation

摘要

A method and system for monitoring electrical isolation of a test device by a test circuit by, in a first state a first switch 12 being in an on state and a second switch 14 in an off state and measuring a primary voltage 16 between a first terminal and an electrical ground 34; in a second state the second switch being on and the first switch being off and measuring a secondary voltage 18 between a second terminal and ground; in a third state the first and second switches both being on and measuring the primary and secondary voltages; estimating an observed leakage resistance based on the primary and secondary voltages of the first and second states; estimating a reference leakage resistance based on the primary and secondary voltages of the third state; and determining the circuit has failed if observed leakage resistance differs from the reference leakage resistance by more than a threshold amount.