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:
Mar. 15, 1988
Filed:
Jun. 06, 1986
Ned Padwa, Tarzana, CA (US);
National Technical Systems, Calabasas, CA (US);
Abstract
A symmetry sensing safety circuit for automatically stopping electrical current flow through a thyristor to an electrical device which is supplied by a source of alternating current electrical energy. The symmetry sensing safety circuit includes a current sensing circuit operatively associated in series with the thyristor and the electrical device for sensing the electrical current flow; an amplifier circuit operatively associated with the current sensing circuit for generating a signal which is proportional to the amplitude and direction of the sensed electrical current flow; an integrating circuit operatively associated with the amplifier circuit for generating a signal which is proportional to the amplitude and direction of the signal generated by the amplifier circuit integrated over a predetermined time interval; a comparison circuit operatively associated with the integrating circuit for generating a signal indicating when the signal generated by the integrating circuit is outside of a predetermined range of values; a relay control circuit operatively associated with the comparison circuit for generating a triggering signal whenever the comparison circuit generates the signal indicating the signal generated by the integrating circuit is outside of the predetermined range of values; an electromechanical relay operatively associated with the relay control circuit and with the source of electrical energy for switching on and off the electrical current flow to the thyristor in response to the triggering signal.