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. 01, 1979
Filed:
Jun. 17, 1977
Peter Pang, Hong Kong, HK;
Gould Inc., Rolling Meadows, IL (US);
Abstract
The primary winding of a saturable transformer, coupled to an a.c. circuit, drives the core of the transformer into saturation during at least a portion of the cycle of an a.c. current flowing through the circuit. A plurality of rise-time indicator pulses, having a duration inversely proportional to the rate of rise of the a.c. current being monitored, is induced in the secondary winding of the saturable transformer. The rise-time indicator pulses appearing in the secondary winding of the saturable transformer are applied to a pick-up circuit which generates a plurality of rectangular pulses whenever the a.c. current exceeds the normal rated value of the circuit. The pulses generated by the pick-up circuit each have a duty cycle inversely proportional to the rate of rise of the a.c. current being monitored. An inverter circuit, responsive to the pulses generated by the pick-up circuit, generates a second series of rectangular pulses having a duty cycle proportional to the rate of rise of the a.c. current being monitored. The second series of pulses are applied to a tripping circuit which monitors the duty cycles of these pulses and interrupts a.c. current flow in said circuit after a time delay which is inversely proportional to the magnitude of the a.c. current being monitored.