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:
Jun. 09, 1987
Filed:
Mar. 08, 1985
James F Sutherland, Plum Boro, PA (US);
Westinghouse Electric Corp., Pittsburgh, PA (US);
Abstract
A redundant power supply/signal conditioner system for a resistance temperature detector includes power supply/signal conditioner modules having first and second output terminals connected to a resistance temperature detector. Diode circuits are connected across the output terminals of each of the power supply/signal conditioner modules to provide an alternate current path when the corresponding power supply/signal conditioner module is removed or is not conductive due to a failure. Each of the power supply/conditioner modules includes a constant current source for supplying a constant current which is slightly different in each of the modules. Each of the modules also includes an overvoltage protection circuit for preventing the voltage output by the constant current source from exceeding a predetermined value and a signal conditioner which outputs a signal based on the temperature detected by the resistance temperature detector. The resistance temperature detector is operated by a current from the module containing the constant current source which generates the highest current and all other constant current sources are controlled by a voltage across a feedback resistor to stay turned off as long as the current is supplied. When the current stops being supplied because the operating constant current source fails or is removed, the next highest voltage current source is turned on due to the drop in current across its feedback resistor and begins supplying current to the resistance temperature detector.