A method and system for monitoring electrical isolation

摘要

A first voltage sensor measures a primary voltage between a first terminal of a device under test and the electrical ground when a first switch and a second switch are in different on states and off states. In a test state, either the first switch or the second switch is in an on state, and in a reference state, both the first switch and the second switch are in on states. An observed insulation resistance is estimated based on measured primary and secondary voltages of the test condition. A reference insulation resistance is based on measured primary and secondary voltages of the reference state. A test circuit has failed if the observed insulation resistance deviates more than a threshold magnitude from the reference insulation resistance.