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:
Nov. 04, 1997
Filed:
Nov. 16, 1995
Mark Edmund Innes, Asheville, NC (US);
Michael G Early, Hendersonville, NC (US);
Eaton Corporation, Cleveland, OH (US);
Abstract
A starter comprising a contactor with an overcurrent relay provides an appropriate cooling interval for each of multiple classes of a load, such as a motor. An analog equivalent of a digital I.sup.2 t value calculated by a microcomputer in the overload relay is maintained by an external capacitor. When the microcomputer loses power following a trip, the capacitor discharges through a resistor at a rate selected to mimic cooling of the associated class of the load. Restart of the load is prevented until the appropriate interval, represented by the time required for the voltage on the capacitor to decay to a common reset value, has expired. The capacitor is charged to a voltage proportional to the I.sup.2 t trip value for the particular class of the load, which for all classes is below the forward drop of the clamping diodes on the microcomputer inputs to prevent discontinuities in the timing.