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:
Aug. 07, 1990
Filed:
Jan. 30, 1989
Richard D Marasch, Germantown, WI (US);
Allen-Bradley Company, Inc., Milwaukee, WI (US);
Abstract
A three-phase electric motor is coupled to each phase line of an electric source by pairs of SCR's coupled in inverse parallel relationship. One of the SCR's in each pair is triggered by a signal from a conventional motor control circuit which regulates the phase angle at which the SCR turns on. The other SCR in each pair is an optically triggered device which is activated by light emitted from an LED in one of the legs of a three-phase rectifier bridge in the control circuit power supply. When the LED within a leg of the power supply is forward biased so as to conduct current, it emits light which triggers a correspondingly biased opto-SCR to supply current to the motor. A separate transistor is connected in parallel across each of the LED's to provide a current shunt path when the motor is to be turned off so that the LED does not emit light and trigger the SCR.