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:
Aug. 12, 1986
Filed:
Nov. 05, 1984
Robert H Harner, Park Ridge, IL (US);
Joseph W Ruta, Elmhurst, IL (US);
S&C Electric Company, Chicago, IL (US);
Abstract
A control circuit is provided for operating a circuit interrupter in response to overcurrent in an alternating-current line in which the circuit interrupter is located. The control circuit includes a transducer for producing output current proportional to the current in the line. A time-current trip signal generator circuit responds to output current representative of moderate overcurrent in the line by producing a trip signal after the passage of a time period that is inversely related to the overcurrent. An instantaneous trip signal generator circuit produces a trip signal after a predetermined time interval in response to output current between a minimum and maximum magnitude and increasing at a rate greater than a selected rate, which conditions indicate the presence of high overcurrent in the line. In the preferred arrangement, the predetermined time interval is measured from the time that the rate of change of the current exceeds a predetermined rate. Accordingly, when the onset of high overcurrent is detected, the current is interrupted with a minimum possible delay while substantially reducing undesired response to noise and false signals.