Method and apparatus for undesired ground path detection in a single- point grounded electrical system

摘要

A method and apparatus for determining the existence of an undesired connection between an electrical system and a desired single- point ground. The electrical system is first disconnected from the desired single- point ground, and is connected to the center point of a resistive divider connected to an isolated voltage source. The voltage of the center point of the resistive divider is monitored and an indication is provided if the monitored voltage indicates the existence of undesired ground paths. The invention also includes elements for measuring the resistance value of a detected undesired ground path, thereby facilitating identification and removal thereof. The invention also includes a voltage clamp which is placed between the electrical system and the desired single-point ground when the electrical system is disconnected from the single-point ground. This voltage clamp provides personnel protection during undesired ground path detection so that, if a power line fault to ground occurs, the electrical system is still protected.