US 12,222,371 B2
Residual current monitoring type B with integrated self-test system and method
Kevin R. Ferguson, Dublin, OH (US); and Jason Armstrong, Lincoln, NE (US)
Assigned to Vertiv Corporation, Westerville, OH (US)
Filed by VERTIV CORPORATION, Columbus, OH (US)
Filed on Dec. 12, 2022, as Appl. No. 18/079,098.
Claims priority of provisional application 63/288,158, filed on Dec. 10, 2021.
Prior Publication US 2023/0184812 A1, Jun. 15, 2023
Int. Cl. G01R 35/00 (2006.01); G01R 15/18 (2006.01); G01R 19/00 (2006.01)
CPC G01R 15/18 (2013.01) [G01R 19/0038 (2013.01); G01R 35/00 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A system, comprising:
a residual current sensor circuitry comprising a residual current sensor configured to measure residual current from a source of AC power;
a controller electrically coupled to the residual current sensor circuitry comprising:
one or more processors; and
a memory configured to store data and instructions executable by the one or more processors, where the instructions include:
transmitting an excitation voltage to an excitation path of the residual current sensor circuitry;
receiving an unbalanced current signal from a detection path of the residual current sensor circuitry;
determining a DC residual current contribution to the unbalanced current signal;
calculating a DC injection scheme configured to negate the DC residual contribution;
injecting a DC current into a DC nulling path of the residual current sensor circuitry based on the DC injection scheme;
receiving a balanced current signal from the detected path; and
determining an AC residual current; and
a testing module configured to send a test AC current and a test DC current through the residual current sensor.