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:
Jul. 23, 1996
Filed:
May. 12, 1994
Samir F Farag, Roswell, GA (US);
Siemens Energy & Automation, Inc., Alpharetta, GA (US);
Abstract
An apparatus for thermal protection of an electric motor is provided, including a monitoring device for generating a signal representative of the current in a conductor supplying electrical power to the electric motor. A control circuit processes the current signal and utilizes the processed signal and motor thermal parameters, including the thermal resistance and thermal capacitance of the rotor, to generate signals representative of the temperature of at least the rotor. A comparator circuit, which may be part of the control circuit, compares the temperature signals to reference maximum temperature signals and produces a control signal when the temperature signals and reference signals satisfy a predetermined relationship. The control signal may be applied to a contactor to interrupt current to the motor. A method for thermal protection of an electric motor is also provided, including thermal modeling of the rotor temperature.