Patent application number | Description | Published |
20080284447 | Method for determining location of phase-to earth fault - A method and apparatus for determining a location of a phase-to-earth fault on a three-phase electric line ( | 11-20-2008 |
20080297163 | METHOD FOR DETERMINING LOCATION OF PHASE-TO-EARTH FAULT - A method and apparatus for determining a location of a phase-to-earth fault on a three-phase electric line of an electric network, comprising determining, when the ratio of a fault current and load current has a first value, a first fault distance line which indicates an estimate of a distance of the fault from the measuring point in relation to an equivalent load distance, determining, when the ratio of the fault current and load current has a second value which differs from the first value, at least one second fault distance line, determining a distance at which the determined fault distance lines intersect when superimposed and determining the distance between the measuring point and the point of fault on the basis of the determined distance or distances of intersection. | 12-04-2008 |
20090267611 | APPARATUS AND METHOD FOR DETERMINING LOCATION OF PHASE-TO-PHASE FAULT OR THREE-PHASE FAULT - A method and apparatus for determining a distance of a phase-to-phase fault or a three-phase fault on a three-phase electric line, the apparatus ( | 10-29-2009 |
20090309612 | METHOD AND APPARATUS FOR DETERMINING CIRCULAR CHARACTERISTIC - A method and a system for determining a circular characteristic for distance protection of a three-phase electric line, the system comprising means for detecting a fault on the electric line, means for identifying a faulted phase or phases of the electric line, means for determining, at a measuring point, a first fault loop impedance by using voltage(s) of the faulted phase(s), a second fault loop impedance by using a polarization voltage and a third fault loop impedance by using predetermined line parameters, and means for determining a radius and midpoint of the circular characteristic. | 12-17-2009 |
20110298468 | METHOD AND APPARATUS FOR DETECTING A PHASE-TO-EARTH FAULT - A method and an apparatus for detecting a phase-to-earth fault on a three-phase electric line of an electric network, the apparatus determining a neutral admittance based on a ratio of a difference between zero sequence currents on the three-phase electric line and a difference between zero sequence voltages in the electric network before an earth fault and during the earth fault. The apparatus also compares the determined neutral admittance, to a predetermined operation characteristic to detect a phase-to-earth fault on the three-phase electric line. The predetermined operation characteristic, when presented on an admittance plane, defines a closed area such that the center of the closed area is offset from the origin of the admittance plane towards a negative susceptance direction and/or towards a negative conductance direction. | 12-08-2011 |
20130035882 | METHOD AND APPARATUS FOR DIFFERENTIAL PROTECTION OF AN ELECTRIC CONNECTION - A method and apparatus are provided for differential protection of a three phase electric connection of an electric system. The apparatus includes means for determining a value of an operate quantity, which operate quantity is based on a difference between current quantities at a first point and a second point of the electric connection, and means for detecting a fault in the electric connection between the first point and the second point if the value of the operate quantity exceeds a value of a predetermined threshold quantity. The operate quantity is based on a difference of residual currents at the first point and the second point, or a quantity indicative thereof, and a coefficient indicative of an angle between a residual voltage of the electric connection and the difference of residual currents at the first point and the second point. | 02-07-2013 |
20130035886 | METHOD AND ARRANGEMENT FOR VOLTAGE MEASUREMENT - A method and an arrangement for voltage measurement with a transformer configuration comprising three single pole voltage transformers having tertiary windings open-delta connected with each other. The arrangement is configured to apply a correction to measured secondary voltages on the basis of one or more parameters of the voltage transformers and/or one or more quantities in a known relation to one or more parameters of the voltage transformers, one or more parameters of a circuit connected to the secondary windings and/or one or more quantities in a known relation to one or more parameters of the circuit connected to the secondary windings, and one or more parameters of a circuit connected to the tertiary windings and/or one or more quantities in a known relation to one or more parameters of the circuit connected to the tertiary windings. | 02-07-2013 |
20130043879 | METHOD AND APPARATUS FOR DETECTING EARTH FAULT - 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. | 02-21-2013 |
20130043894 | METHOD AND ARRANGEMENT FOR DETERMINING IMPEDANCE VALUES - A method and an arrangement are provided for determining values of impedance parameters related to a transformer configuration including three single pole voltage transformers each respectively having at least a primary winding, a secondary winding and a tertiary winding. The primary windings are connected to phases of a three phase electric system. The arrangement is configured to conduct an earth fault in the three phase electric system, measure a primary voltage from the faulted phase, measure secondary voltages from the secondary windings, and determine values of one or more impedance parameters related to the transformer configuration on the basis of the measured primary voltage, the measured secondary voltages and an equation relating the primary voltage to the secondary voltages and the one or more impedance parameters. | 02-21-2013 |