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:
Dec. 26, 1989
Filed:
Nov. 09, 1987
Louis W Schornack, Park Ridge, IL (US);
Perma Power Electronics, Inc., Chicago, IL (US);
Abstract
A battery-operated standby power supply includes a circuit for the detection of failures in A.C. power line voltage provides immediate detection of power failure even if such failure occurs during the times of line voltage axis crossings. This is accomplished by providing and monitoring the amplitude of a synthesized waveform representing a full-wave rectified replica of the line voltage, combined with a 90.degree. phase-shifted full-wave rectified replica of the line voltage waveform. The composite waveform has a peak-to-peak excursion of approximately 20% about a DC average without nulls. The phase-shifted waveform replicas are produced by a phase shift network configured to provide a strong differentiating function, thereby causing the phase-shifted replicas to reflect virtually instantaneously failure of the power line voltage, and in particular failure in the vicinity of an axis crossing, by an immediate change in amplitude. Transient overvoltages and undervoltages are similarly reflected. Suitable comparators are used to detect excursions beyond preset limits to produce a control signal which is used to actuate a battery-operated standby power supply from standby to power delivery mode.