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1. (WO2018200010) CIRCUIT FOR MITIGATING ELECTRIC SHOCK

Pub. No.:    WO/2018/200010    International Application No.:    PCT/US2017/033075
Publication Date: Fri Nov 02 00:59:59 CET 2018 International Filing Date: Thu May 18 01:59:59 CEST 2017
IPC: H02H 1/00
H02H 5/12
G01R 27/16
H05B 33/08
H02H 3/24
Applicants: ENERGY FOCUS, INC.
Inventors: HEILMAN, Jeremiah A.
DAVENPORT, John M.
Title: CIRCUIT FOR MITIGATING ELECTRIC SHOCK
Abstract:
A circuit for mitigating electric shock including an external impedance detection circuit (120) and a test and holdoff circuit (140). The external impedance detection circuit detects a presence of an external impedance (R16), such as by detecting a relative change in voltage from a startup condition and a test condition. The test and holdoff circuit inhibits operation of a power converter which delivers power to be consumed by a load. The startup condition is defined by mains power applied to the circuit with negligible power consumed by a load. The test condition is defined by non-zero power delivered to the load. According to another aspect, the external impedance detection circuit measures an input voltage using a high input power which is greater than a shock hazard threshold at a duration less than a threshold time duration and determines the presence of the external impedance based on low pass filters having different time constants.