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1. (WO2013155356) NEUTRAL GROUNDING RESISTOR MONITOR

Pub. No.:    WO/2013/155356    International Application No.:    PCT/US2013/036256
Publication Date: Fri Oct 18 01:59:59 CEST 2013 International Filing Date: Fri Apr 12 01:59:59 CEST 2013
IPC: H02H 3/16
H02H 3/26
Applicants: LITTELFUSE, INC.
Inventors: VANGOOL, Michael P.
BAKER, Geoffrey J.
Title: NEUTRAL GROUNDING RESISTOR MONITOR
Abstract:
A device for monitoring a neutral grounding resistor (NGR), including first and second NGRs electrically connected in parallel, a rectifier circuit electrically connected in series with the second NGR and a voltage source and a logic resistor electrically connected in series with the second NGR. A logic circuit measures current passing through the logic resistor and determines the resistance of the first NGR based on the measured current and the resistance of the second NGR. As such, a failed-open or failed-short condition of the first NGR may be identified based at least in part on the determined resistance of the first NGR.