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:
Jun. 29, 1993
Filed:
May. 10, 1991
Paul Baran, Atherton, CA (US);
Ronald S Palmer, Sunnyvale, CA (US);
Metricom, Inc., Los Gatos, CA (US);
Abstract
An isothermal current shunt device with excellent temperature coefficient of resistivity characteristics stability for use in a power measuring circuit having a wide temperature and dynamic range and particularly for customers of electric utility companies, and it includes a first arm having a first flange portion, a second arm having a second flange portion, and a bridge means coupling the first arm to the second arm wherein the bridge means is a monolithic sintered powdered-metal piece having a block portion and a loop portion. The block portion has a first face juxtaposed to and electrically coupled to the first flange portion of the first arm and a second opposing face juxtaposed to and electrically coupled to the second flange portion of the second arm. This configuration allows a majority of electrical current to conduct between the first arm and the second arm. The loop portion is outside the first face and the second face of the block portion and conducts a minority of current. A notch is formed in the block portion where the shunt portion meets the block portion and is used to control the current densities in both the block portion and the loop portion. The central axis of the loop is disposed orthogonal to the axis between the first flange portion and the second flange portion. The loop portion serves as a primary in a current transformer with a secondary mounted on a core in the loop. The transformer further includes a magnetic shield mounted on the loop to shield the transformer from stray magnetic fields that would otherwise distort current measurements obtained by use of the transformer.