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:
Sep. 14, 1999
Filed:
Dec. 05, 1997
ABB Research Ltd., Zurich, CH;
Abstract
Without special measures, a fiber-optic current sensor coil (11) and fiber-optic .lambda./4 time delay elements (9, 9'), which are connected in series with the current sensor coil (11), are temperature-dependent with respect to a relative phase lag of light passing through. In order to avoid a temperature correction or temperature compensation, the current sensor coils (11) and, if appropriate, also the .lambda./4 time delay elements (9, 9') are annealed, so that virtually no mechanical stresses remain in the optical fibers. The current sensor coil (11) is preferably mounted unrestrained in a capillary (20) filled with a protective gas. The capillary (20) is embedded in a gastight fashion in a potting compound (22) made from polyurethane, and is thus also mechanically protected.