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. 25, 1995
Filed:
Dec. 21, 1992
Brian R Pelly, Palos Verdes Estates, CA (US);
Henry N Tachick, Pound, WI (US);
Dairyland Electrical Industries, Inc., Oregon, WI (US);
Abstract
An isolator surge protector for use with corrosion protection systems which are an inherent part of or coupled to an electrical power system, for power transformers, and for DC transmission systems, where it is necessary to present a high impedance to DC and a low impedance to AC up to a predetermined voltage level. Anti-paralleled thyristors in the isolator surge protector turn on during power surges. A bypass circuit insures turn off of the thyristors after a triggering event such as lightning or a 60 Hz surge has ended. The bypass circuit shunts DC bias currents, such as that which may be provided by a DC bias voltage source for cathodic protection, from the thyristors to ensure that the voltage across each thyristor falls below its holding voltage or current, and thus prevents the thyristor from being stuck in a continuous conduction mode. Power to operate the bypass circuit may be tapped from the surge which caused the thyristor to trigger so that the bypass circuit operates autonomously. The circuit may also operate with an auxiliary power supply to provide the required operating power and to turn off the thyristors.