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:
Sep. 09, 1997
Filed:
Nov. 29, 1995
Brian Thomas, San Francisco, CA (US);
Hugh Duffy, Cupertino, CA (US);
Raychem Corporation, Menlo Park, CA (US);
Abstract
An overcurrent protection system which will give a rapid response to overcurrents which cause a reduction in the voltage across the load, e.g. a partial or complete short across the load, and is particularly suitable for protecting circuits against relatively small overcurrents, comprising: a circuit interruption element which, in the operating circuit, is connected in series between the electrical power supply and the electrical load, and which has (1) a closed state which permits the flow of a normal current, I.sub.NORMAL, through the circuit interruption element, and (2) an open state which permits the flow of at most a reduced current, substantially less than I.sub.NORMAL, through the circuit interruption element; a control element which, in the operating circuit, is connected in parallel with the load, and which has (1)(i) an on state, when the voltage across the control element is a normal voltage, V.sub.NORMAL, and (ii) is converted to an off state, when the voltage across the control element falls to a value V.sub.FAULT, or less, and (2) is functionally linked to the circuit interruption element so that when the control element is in the on state, the circuit interruption element is in the closed state, and when the control element is in the off state, the circuit interruption element is in the open state; and a bypass element which (1) is connected in parallel with the circuit interruption element, and (2) has (i) a start-up state such that, if the circuit interruption element is in the fault state and a current I.sub.NORMAL is passed through the bypass element, the voltage across the control element is greater than V.sub.FAULT, and (ii) a stopped state such that if the circuit interruption element is in the fault state as a result of the voltage across the control element having fallen to a value V.sub.FAULT or less, the current through the bypass element is such that the voltage across the control element remains at a value of V.sub.FAULT or less.