Bbc Brown, Boveri & Company, Limited

Michael Vitins

Otto Lanz

Hans Glavitsch

Jiri Mastner

A method and apparatus for detecting a fault and also the direction of a fault in electric lines, wherein voltage (Su) and current step signals (Si) corresponding to the transient components in the line voltage and line current are derived; the instantaneous values of these step signals (Su, Si) define, in a co-ordinate system formed by the step signals (Su, Si) themselves, a point which passes through a line of motion (B) after the occurrence of a fault; and if the point transgresses a triggering boundary (AI, AII, AIII, AIV) in the co-ordinate system the fault is detected. In this event the direction of the fault is found from the quadrant (QI, QII, QIII, QIV) in which the transgression takes place. At a predetermined time after entry of the point into a boundary zone provided in one quadrant, located in the line of motion ahead of a triggering boundary in next adjacent quadrant, a triggering boundary in at least the next adjacent quadrant is adjusted to a greater distance from the origin of the co-ordinate system which is located in the same semicircular space bounded by the axis of the voltage step signal (Su). This measure considerably increases the reliability of detection with respect to fault direction and, in addition, reduces the time required for fault detection.

Method for detecting a fault or also the direction of a fault in

By forming current jump or surge signals and voltage jump or surge signals, in accordance with the changes as a function of time of the line current and line voltage in relation to the steady-state course of the current and voltage and comparison of such jump or surge signals with a threshold value, dependent upon the other jump or surge signal, or an appropriate threshold value function, there can be derived trip boundaries in the surge signal plane. Exceeding such trip boundaries in a direction from the inside towards the outside can be utilized as a fault criterion for producing a trip signal. With suitable trip boundaries, at least inclined in sections towards the coordinate axes owing to the aforementioned dependency of the comparison threshold values, which trip boundaries also may be curved, and arranged in spaced relationship from the coordinate-null point in the four quadrants of the surge signal-coordinate system there is realized a rapid fault detection which is comparatively foolproof against faulty tripping and by determining the quadrants where there occurs the initial exceeding of the threshold value, there likewise can be realized an equally rapid and positive fault-direction detection.

Method and apparatus for fault and/or fault direction detection

An arrangement for supervising an electrical line for short circuits in which current and voltage signals are derived from the line current and line voltage at a predetermined measuring point. The current and voltage signals are relatively weighted by multiplying at least one of these signals by a weighting factor which is at least approximately free of phase rotation. At least one auxiliary signal is formed corresponding to the sum or difference in each case of a pair of relatively weighted current and voltage signals. An amplitude comparison is carried out between the auxiliary signal and a reference signal. The weighting factor is related to the current signal and the voltage signal, and is a quantity at least approximately corresponding to the characteristic line resistance or its reciprocal value. Two auxiliary signals may be formed by addition and subtraction respectively of a pair of relatively weighted current and voltage signals, and one of these auxiliary signals is used, in the amplitude comparison, as a reference signal for the other.

Method and apparatus for supervising an electrical line for short

An apparatus for the localization of a fault on a line wherein there is formed from at least one measurement signal derived from a line voltage and at least one measurement current derived from a line current an evaluation signal characterizing the direction and/or distance of a fault location with respect to a reference location on the line determinable by at least one regulation or adjustment magnitude, the apparatus comprising a voltage- and current measuring device provided at the measurement location and a signal processing- and evaluation circuit. The signal processing- and evaluation circuit possesses at least one reference location-adjustment input and there is provided means defining an operative connection, which changes the momentarily effective reference location adjustment, between an output of the evaluation circuit and the reference location-adjustment input.

Apparatus for localization of a line fault through the use of

A method of and apparatus for the detection of short-circuits on lines operated with voltages and currents containing an alternating component, by detecting the temporal progression of the voltage and current at a measurement location in the form of measurement voltages and measurement currents. From the measurement voltage and measurement current or from magnitudes derived therefrom there are formed traveling wave signals of the form:

Method and apparatus for detection of short circuits by phase monitoring

A method of and apparatus for locating a fault on a line in which there is formed from the voltage and current at a test or measuring location at least one signal (travelling-wave signal) associated with a travelling wave on the line and its variation with time at the test location. There are formed a number of pairs of oppositely moving travelling-wave signals corresponding to the number of phases or conductors of the line and with these travelling-wave signals or signals derived therefrom as integrands there are formed at least two time-integrals each of which is associated with a direction of wave propagation on the line. The time integrals are combined into an evaluation function characterizing the fault direction or fault distance with respect to the test or measuring location, the evaluation function corresponding to a relation prevailing at the fault location between the oppositely moving travelling waves on the line.

Method and apparatus for locating a fault on a line by means of

A method for locating a fault on a line wherein starting from a fault-free operating state of the line there is derived a substitute-measurement voltage signal which corresponds at least approximately to a frequency component of a line voltage both in magnitude and phase and is approximately independent of breakdown of the line voltage at least for a limited time interval. The substitute-measurement voltage signal is used to form at least one substitute-traveling wave signal and a substitute-evaluation signal.

Method for locating a fault on a line near to a measuring location with

A process and apparatus for locating faults on a line, wherein at least one signal (travelling-wave signal) associated with a progression thereof at the measuring location is formed from the voltage and current at a measuring location. There are formed travelling-wave signals corresponding in number to the phases or conductors in the line and decoupled from one another in relation to the line inductances and line capacitances. At least two time-integrals are formed with these travelling-wave signals or signals derived therefrom as integrands, each time integral being associated with one direction of wave-propagation on the line. These time-integrals are processed by an evaluating function which characterizes by way of its sign and magnitude the direction and distance of the fault from a predetermined reference location on the line, which function corresponds to a relationship prevailing at the fault location between the travelling waves proceeding in opposite directions on the line.

Process and apparatus for locating faults on a line through the use of

A method of, and apparatus for, detecting a fault location at an electrical conductor which entails forming a wave voltage and therefrom together with a measurement voltage a first wave function and a second wave function. Weighted functions are formed by multiplication of the first and second wave functions with a substantially cosine-type and sine-type signal, respectively, of a predetermined reference frequency. Integral functions are formed from the weighted functions. There is formed the product difference from those integral functions produced by cosine and sine weighting, respectively, of the first and second wave functions and integration, and/or the product sum from those integral functions formed by cosine weighting of the first and second wave functions or sine weighting of the first and second wave functions, respectively, and there is checked the sign of at least one of such product polynomials.

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Zurich, Switzerland

Michael Vitins