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:
Mar. 17, 2015
Filed:
Feb. 10, 2012
Ari Wahlroos, Vaasa, FI;
Janne Altonen, Toijala, FI;
Ari Wahlroos, Vaasa, FI;
Janne Altonen, Toijala, FI;
ABB Technology AG, Zurich, CH;
Abstract
A method and an apparatus for detecting an earth fault on a three-phase electric line are provided. The apparatus includes means for determining a neutral admittance on the basis of a residual current and a residual voltage, means for comparing the determined neutral admittance to a predetermined operation characteristic to detect an earth fault on the three-phase electric line, and means for determining one or more harmonic components of the residual current and one or more harmonic components of the residual voltage. The harmonic components have frequencies n*fn such that n≧2 and fn is a fundamental frequency. The means for determining a neutral admittance are configured to use at least one of the determined one or more harmonic components of the residual current and at least one of the determined one or more harmonic components of the residual voltage for determining the neutral admittance.
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