| US 7,514,933 B2 | ||
| System and method for determining location of phase-to-earth fault | ||
| Janne Altonen, Toijala (Finland); and Ari Wahlroos, Vaasa (Finland) | ||
| Assigned to ABB OY, Helsinki (Finland) | ||
| Filed on May 09, 2006, as Appl. No. 11/429,956. | ||
| Claims priority of application No. 20055232 (FI), filed on May 17, 2005. | ||
| Prior Publication US 2006/0291113 A1, Dec. 28, 2006 | ||
| Int. Cl. G01R 31/08 (2006.01) | ||
| U.S. Cl. 324—522 [324/512] | 23 Claims |
| 1. A fault detecting device for locating a phase-to-earth fault in a three-phase electric line of an electric network, the
fault detecting device being configured to:
monitor current and voltage quantities of the three-phase electric line at a measuring point;
detect a phase-to-earth fault on the three-phase electric line and a faulted phase of the three-phase electric line;
calculate load-compensated zero and negative sequence currents by using a ratio of a total zero sequence admittance of the
electric network and a zero sequence admittance of the electric network without the faulted electric line and by using a negative
sequence current of the faulted phase and a zero sequence current;
calculate a load-compensated phase voltage of the faulted phase by using the compensated zero sequence current; and
calculate a distance between the measuring point and a point of fault using the compensated negative sequence current and
the compensated phase voltage and an equation relating the current and voltage quantities to the distance.
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