Electromagnetic and radio frequency interference suppression for ground fault circuit interrupters
OwnerHarold L. Taylor, Elton C. Johnsoninventors
Life of this patent
Estimating the term…
Abstract
A ground fault interruption circuit has a detector circuit coupled to an electrical distribution circuit load to detect ground fault conditions in the load. A filtering circuit connected between the detector circuit and distribution network comprises a pi-network filter for attenuating common-mode electromagnetic interference and differential-mode electromagnetic interference. The pi-network filter includes three filter portions which together provide a third order filter to attenuate the interference signals at the frequencies of interest.
Claims19
A ground fault interruption circuit, said circuit disconnecting a load from an electrical distribution line in response to ground fault conditions in the load, comprising:
- coupling means coupled to an electrical distribution network load providing ground fault imbalance signals;
- detector circuit means connected to receive said ground fault imbalance signals and providing a trigger signal when a ground fault condition exists;
- control circuit means disconnecting the load from the line in response to said trigger signal;
- a filtering circuit connected to said coupling means and said detector circuit for attenuating electromagnetic interference signal components from said ground fault signals;
- first and second relative ground planes;
- and
- a power supply circuit generating power for said detector circuit;
- wherein said supply circuit is grounded to the first relative ground plane, and the coupling circuit and filtering circuit are grounded to the second relative ground plane, to separate noise signals in the respective circuits.
A ground fault interruption circuit, said circuit disconnecting a load from an electrical distribution line in response to ground fault conditions in the load and comprising:
- coupling means coupled to an electrical distribution network load for providing ground fault imbalance signals;
- detector circuit means connected to receive said ground fault imbalance signals and providing a trigger signal when a ground fault condition exists;
- control circuit means disconnecting the load from the line in response to said trigger signal;
- and
- a filtering circuit connected to said coupling means and said detector circuit and attenuating electromagnetic interference signal components from said ground fault signals;
- wherein the filtering circuit comprises a first filter element attenuating differential-mode electromagnetic interference signals and a second filter element attenuating common-mode electromagnetic interference signals.
A ground fault interruption circuit, said circuit disconnecting a load from an electrical distribution line in response to ground fault conditions in the load and comprising:
- coupling means coupled to an electrical distribution network load and providing ground fault imbalance signals, said coupling means comprising a sense transformer having a primary coupled to the electrical distribution line and a secondary winding having opposite ends;
- detector circuit means connected to receive said ground fault imbalance signals and providing a trigger signal when a ground fault condition exists;
- control circuit means disconnecting the load from the line in response to said trigger signal;
- a filtering circuit connected to said coupling means and said detector circuit and attenuating electromagnetic interference signal components from said ground fault imbalance signals, said filtering circuit comprising a pi-network filter having a first, shunt portion comprising a capacitor connected across the secondary winding, a second, series portion comprising inductors respectively connected in series with opposite ends of the secondary winding, and a third, shunt portion comprising two capacitors respectively connected in shunt with opposite ends of said secondary winding after said second portion, said filtering circuit attenuating differential-mode and common-mode electromagnetic interference signals form said ground fault imbalance signals;
- first and second relative ground planes;
- and
- a power supply circuit for generating power for said detector circuit;
- wherein said supply circuit is grounded to the first relative ground plane, and the coupling circuit and filtering circuit are grounded to the second relative ground plane, to separate noise signals in the respective circuits.
A ground fault interruption circuit, said circuit disconnecting a load from an electrical distribution line in response to ground fault conditions in the load and comprising:
- coupling means coupled to an electrical distribution network load and providing ground fault imbalance signals;
- a detector circuit connected to receive said ground fault imbalance signals and providing a trigger signal when a ground fault condition exists;
- control circuit means disconnecting the load from the line in response to said trigger signal;
- a filtering circuit connected to said coupling means and said detector circuit and attenuating electromagnetic interference signal components from said ground fault signals;
- and
- a pair of relative ground planes respectively conductively coupled to (a) the detector circuit and the filtering circuit and (b) the electrical distribution line.
A ground fault interruption circuit, said circuit disconnecting a load from an electrical distribution line in response to ground fault conditions in the load and comprising:
- coupling means coupled to an electrical distribution network load and providing ground fault imbalance signals;
- a circuit board;
- a detector circuit, configured on the circuit board, connected to receive said ground fault imbalance signals and providing a trigger signal when a ground fault condition exists;
- control circuit means disconnecting the load from the line in response to said trigger signal;
- a filtering circuit, configured on the circuit board, connected to said coupling means and said detector circuit and attenuating electromagnetic interference signal components from said ground fault signals;
- and
- a pair of relative ground planes configured on the circuit board, which are respectively conductively coupled to (a) the detector circuit and the filtering circuit and (b) the electrical distribution line.
Dependencies are inferred from the claim text.