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:
Feb. 10, 1987
Filed:
Oct. 03, 1984
Joseph W Ruta, Elmhurst, IL (US);
S&C Electric Company, Chicago, IL (US);
Abstract
A trip signal generator comprises a circuit possessing an inverse time-current characteristics for producing a trip signal in response to the occurrence of overcurrent in an alternating current line. The trip signal is produced after the passage of some time period, which varies inversely with the difference between the absolute magnitude of the overcurrent and a threshold current. The circuit includes a portion which produces pulses at a rate proportional to the difference between the absolute magnitude of the overcurrent in the line and the threshold current. The circuit produces no pulses when the line current is less than or equal to the threshold current. The circuit includes a counter for counting the pulses and for producing the trip signal after the counting of a selected number of pulses. Another portion of the circuit enables the counter when overcurrent is in the line, but resets the counter and prevents its operation when the line current is less than or equal to the threshold current. The counter may include a plurality of selectable outputs, each corresponding to a different count, thereby permitting the length of the delay before the trip signal is generated to be varied by selecting a different one of the outputs. The circuit also may include one or more range selectors for automatically selecting among two or more counter outputs so as to produce the trip signal after the passage of different ranges of time period corresponding to different ranges of overcurrent.