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:
May. 10, 1988
Filed:
Mar. 31, 1987
Bruce R Quayle, Asheville, NC (US);
Edward C Prather, Hendersonville, NC (US);
Westinghouse Electric Corp., Pittsburgh, PA (US);
Abstract
A motor protection relay is taught in which the temperature of a rotating rotor is inferred from the current flowing in the lines which supplies the motor and from resistance temperature detection devices in the stator of the motor. By utilizing a periodic predictable established interrupt routine within the software which controls the microprocessor which in turn controls the monitoring device the time based model for inferring rotor temperature can be freed of a requirement to use a fixed sampling time rather the time for calculations can be variable. The total number of counts that particular interrupt routine has taken place will be factored into the calculations to make the calculations accurate. The thermal model is further improved by expressing it in terms of current squared times time so that the component portions of the equation which represents the thermal model can use accumulator inputs into which values of line current squared have been previously placed.