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. 27, 1999
Filed:
Sep. 29, 1997
Robert H Katyl, Vestal, NY (US);
Robert M Murcko, Binghamton, NY (US);
David W Dranchak, Endwell, NY (US);
JRS Technology, Inc., Endicott, NY (US);
Abstract
A large inrush of electrical current flow occurs during a short interval after switch closure, when power is applied to a conventional electronic ballast commonly used for fluorescent lighting. This inrush current flows as the main filter capacitor in the ballast charges to its steady state value. For a lighting circuit that contains a multiplicity of ballasts, the combined magnitude of the inrush is potentially large enough to cause contact failure of the switching device due to arcing and contact welding. The invention features a circuit for limiting inrush current having a current-limiting resistor that is active for a brief interval during startup. The resistor is subsequently bypassed from the principal current path by a switching transistor. The transistor is controlled by electrical signals normally present in conventional electronic ballasts. The advantage of the inventive circuitry is the use of only two inexpensive components to accomplish inrush current protection.