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1. (WO2011153251) UTILITY GROUND DETECTION

Pub. No.:    WO/2011/153251    International Application No.:    PCT/US2011/038776
Publication Date: Dec 8, 2011 International Filing Date: Jun 1, 2011
IPC: H02H 3/00
Applicants: AEROVIRONMENT, INC.
FLACK, Albert
BERMAN, Scott Garret
Inventors: FLACK, Albert
BERMAN, Scott Garret
Title: UTILITY GROUND DETECTION
Abstract:
In an embodiment, a missing utility ground detection circuit includes a pair of balanced resistors each connected to receive utility voltage from a different one of a pair of utility power lines, the balanced resistors being connected together at a summing node to be capable of summing the voltages from the pair of utility power lines. It includes an unbalance resistor connected to shunt voltage from one of the utility power lines. It has a summing amplifier with an input coupled to the summing node and to a reference voltage, and an input coupled to a second reference voltage. It has an averaging circuit connected at the output of the summing amplifier. A comparator is provided having an input connected to the averaging circuit an input connected to a threshold voltage.