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:
Jan. 16, 2001
Filed:
Oct. 22, 1999
Richard R. Billig, Los Gatos, CA (US);
Steven B. Carlson, Portland, OR (US);
Power Innovations, Inc., Los Gatos, CA (US);
Abstract
A thyristor-based forward phase control (FPC) system for controlling the power delivered to a load from an AC power source employs a short-circuit test cycle to protect the thyristor from damage. Upon activation of the FPC system, the thyristor is triggered at a phase less than one-twelfth cycle before a zero crossing so that, if there is a short, the resulting peak current will be insufficient to damage the thyristor but will exceed a predetermined threshold current corresponding to a repetitive overload current. If during the test cycle, the threshold current value is crossed, the FPC system does not trigger the thyristor again and does indicate that a short exists. The threshold current value is selected to correspond to the thyristor's steady-state load rating. If it is exceeded during normal (including warm-up and request-based) operation, steps can be taken to address an overload condition. Accordingly, the same circuitry used for general overload protection can be used as well for short-circuit protection.