Title: Ground fault protective systems with predetection neutralization of reactive currents

Abstract: Ground fault protective systems are disclosed in which fault signals are generated in response to differential currents carried by electrical supply lines. A circuit breaker interrupts power on the supply lines when the fault signals exceed a given magnitude and duration. Downstream reactances to ground from one or more supply lines give rise to spurious fault signals which do not characterize true ground fault conditions. These spurious fault signals are cancelled prior to detection by means of neutralizing auxiliary circuits. The resulting fault signals exhibit a high signal-to-noise ratio.

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Inventors: Gross, Thomas A. O. (Lincoln, MA, US)

Application Number: 817579
Filing Date: 1977-07-21
Publication_date: 1979-02-06
Assignee:
Primary Class(es): 361/45 361/44, 361/87
Other Classes:
US Patent Ref:

1956461	Apr, 1934	Butow	361/44.
2357138	Aug, 1944	Seeley	361/47.
3555360	Jan, 1971	Lee et al.	361/45.
3617809	Nov, 1971	Penn et al.	361/45.
3710190	Jan, 1973	Althoff	361/44.
3732463	May, 1973	Dale	361/45.
3769548	Oct, 1973	Pardue	361/45.
3848159	Nov, 1974	Nye et al.	361/45.
3859567	Jan, 1975	Allard	361/45.
3976918	Aug, 1976	Clark	361/45.
4024435	May, 1977	Gross	361/45.
4056837	Nov, 1977	Misencik et al.	361/45.

Other Refs: 647533

Jul, 1937	DE

Primary Examiner: Salce, Patrick R.
Assistant Examiner:
Attorney: Roberson; William D.