The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 08, 2011
Filed:
Dec. 29, 2008
Paul A. Reid, Cedar Rapids, IA (US);
Robert Erger, Swisher, IA (US);
Paul A. Reid, Cedar Rapids, IA (US);
Robert Erger, Swisher, IA (US);
Other;
Abstract
A circuit that includes a single grounded fault sensing transformer coupled to a resonant circuit that produces an output signal used by a microcontroller to determine a load current flowing through at least two conductors passing through the center of the sensing transformer. The microcontroller pings the resonant circuit, causing an impulse disturbance at the output signal, and the microcontroller calculates the inductance component of the resonant circuit based on the frequency of the decaying output signal. The microcontroller calculates the resistive core loss as a function of a known resistance of the resonant circuit, a known capacitance of the resonant circuit, the calculated inductance, and the determined rate of decay of the output signal. The calculated resistive core loss is compared to a table or to a polynomial function that characterizes known resistive core losses with known load currents to determine the load current corresponding to the calculated resistive core loss.