Protective relay apparatus
AssigneeWestinghouse Electric Corp.
InventorWilliam A. Strickland, Jr.
Life of this patent
Estimating the term…
Abstract
Protective relay apparatus which performs a segregated phase current comparison of a three-phase protected line section, with a single relay at each end thereof for making the phase current comparison. The single relay includes a rectifier arrangement which provides a signal responsive to the largest phase current of a predetermined polarity, at any instant. In response to a fault detection, it successively phase compares the signals from its rectifier with the signals of the corresponding phases from the rectifier in the relay at the other line end.
Claims6
Protective relay apparatus for protecting a three-phase power line section having first, second and third phase currents flowing between first and second line ends of the protected section, comprising:
- first means at each line and providing one of first, second and third signals indicative of the largest of the first, second and third phase currents, respectively, flowing at any instant;
- second means at each line end for communicating the first, second and third signals to the other line end;
- third means at each line end for phase comparing each of the first, second and third signals from its line end with the like numbered signal from the other line end;
- and
- fourth means for isolating the protected section in response to a predetermined phase relationship between any pair of compared signals.
Dependencies are inferred from the claim text.