Westinghouse Electric Corporation

The United States of America As Represented by the Secretary of

Electric Power Research Institute Incorporated

John H Cooper

Charles D Bice

William H South

David W Fugate

Michael L Fenger

Fred M Dietrich

In an electrical power system for a residential building, a multi-conductor cable supplies power to loads in the residential building from a power supply. A net current returning from loads to the power supply via alternative conductive paths different from the neutral conductor in the cable creates a magnetic field in the vicinity of and inside of the residential building. A net current control device, including a ferromagnetic core, is attached to the multi-conductor cable in order to increase the impedance of the alternate conductive paths to the net current and to increase the net current flowing along the neutral conductor. Various modifications of the net current control device are disclosed.

Net current control device

A protective relay for detecting power arcing faults on a low-voltage spot network. The protective relay can monitor the voltage difference between each phase conductor, the voltage difference between each phase conductor and the neutral conductor, or the current on each phase conductor. Using one of these three sets of values, the protective relay first filters the input signal so that only frequencies indicative of a power arcing fault on the low-voltage spot network are analyzed. The signals passed by the filter are amplified, rectified, and averaged and the peak of each signal detected. If the peak has a duration longer than a predetermined value, a fault indication is provided.

Protective relay circuit for detecting arcing faults on low-voltage spot

An improved electrical cable coupler incorporates rotatable protective covers on its plug and socket members to automatically protect the plug and socket contacts against contamination when the plug and socket members are disconnected and to allow the contacts to be electrically engaged when the plug and socket members are connected together. Each protective cover includes one or more openings which correspond in number and location to the electrical contacts on the plug and socket members. Each cover is rotatable between a protective position in which its openings are out of alignment with the respective contacts to provide protection against contamination and an operative position in which the openings are aligned with the respective contacts to expose the contacts for electrical engagement. The protective covers are adapted to interlock when moved into face-to-face engagement so that, by twisting the plug and socket members in opposite directions, the cover openings are moved into registration with the contact elements to allow electrical engagement therebetween. At least one of the protective covers is slidably mounted to permit relative axial movement of the plug and socket members to bring the contacts into electrical engagement.

Electrical cable coupler with rotatable protective covers

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Murrysville, PA, United States of America

John H Cooper