Nulling Devices

One way to mitigate neutral-to-earth voltage is to deliver a controlled current to earth. Voltage between a point in the neutral/grounding system and an isolated reference ground or grounds is used as the input to a differential amplifier. Current delivered to a remote-grounding-electrode system is then adjusted to null out the measured neutral-to-earth voltage.

One of the systems that is an active suppression device for application on the main service panel in the dairy barn is the Electronic Grounding System from EGS, Inc., P.O. Box 2436, LaCrosse, Wisconsin 54602-2436.