Bbc Brown, Boveri & Company, Limited

Otto Lanz

Michael Vitins

Rene Dandliker

Georg Mastner

Martin Maschek

Jiri Mastner

Francois Mottier

In an electrical power distribution system, line disturbances produce voltage and current travelling waves, or step-change signals, that are phase-shifted 90.degree. relative to each other. A simulation signal is derived from the current step-change signal and is in phase with the voltage step-change signal. The two in-phase signals are combined and compared with established limit values to determine when a fault occurs.

Method for detecting a disturbance along a conductor in an

A digital integrator (1) having a 16-bit output is followed by a first 12-bit digital/analog converter (2a) which is supplied with the output bits 1-11 and 16 of the integrator (1) and which forms a first tracking loop with a first subtracter (3a), which forms a first difference signal from the output signal, proportional to the input signal of the analog/digital converter, of a first amplifier (4a) and the output signal of the first digital/analog converter (2a), and a tracking circuit (6) which generates tracking signals for the integrator (1) on the basis of the difference signal. To extend the dynamic range, a second 12-bit digital/analog converter (2b) is present which is supplied with bits 5-16 from the output of the integrator and which forms a second tracking loop with a second subtractor (3b) and a second amplifier (4b), the gain factor of which is 1/16th of the gain factor of the first amplifier (4a), to which loop a control logic (15) switches over when the range which can be covered with the first digital/analog converter (2a) is exceeded. Switching back takes place at the next zero crossing, that is to say change of the most significant bit. The digital/analog converter is particularly suitable for processing the output signal of a current or voltage converter.

Analog/digital converter

A method and apparatus for mutually adjusting the positioning of planar, generally transparent components such as for example, small liquid-crystal plates. The plates are provided with marks specially structured to diffract incident collimated light, in a shape or direction which is characteristic for each plate. By means of a convergent lens, characteristic diffraction images produced by passing light through the marks are depicted on a detector located in the image plane of the convergent lens. The respective characteristic images of the marks are stopped down individually by means of a diaphragm located in the lens focal plane. The diaphragm can periodically be closed partially, so that control signals for the electronic displacement of each plate can be derived individually from the particular positions of the images of the marks on the detector, corresponding to the positions of the plates.

Adjusting method and apparatus for positioning planar components

A method and apparatus for adjusting the relative positioning of planar transparent objects, such as the two glass plates of a liquid crystal display, (LCD). Textured transparent markings are disposed on the planar transparent objects. Thereafter a collimated light beam is passed through the transparent textured markings and refracted thereby. Images of the textured markings are observed and detected, whereupon the relative positioning of the planar transparent objects is adjusted until the detected images are aligned in a predetermined spatial orientation. Also disclosed is a novel liquid crystal display having the transparent textured markings provided on the transparent electrode layers of the LCD device.

Method and apparatus for adjusting the relative positioning of planar

A method of, and apparatus for, locating a fault on a line, wherein current and voltage signals weighted relative to one another are formed from measurement signals corresponding to the line current and line voltage at a measurement location and after superimposing are used for a phase detection. At least one of the current signals or voltage signals is multiplied by a weighting factor at least approximately devoid of phase shift. From mutual relatively weighted current- and voltage signals there is determined the phase angle of a sinusoidal component of at least one auxiliary signal -- corresponding to the sum or difference of a respective pair of mutually relatively weighted measurement currents and measurement voltages -- in relation to a reference phase position which can be correlated to a reference location at the line.

Method and apparatus for locating a fault on a line

An apparatus for localization of a line fault wherein at a measuring location on the line there is provided a voltage- and current-measurement circuit, the outputs of which carry a number of voltage-current signal pairs independent of one another with respect to the line inductances and line capacitances. A summation circuit having at least two outputs is connected with the measurement circuit through the agency of at least one voltage- and one current signal channel. In the summation circuit there are additively and subtractively superimposed at least one pair of mutually independent voltage- and current signals, if necessary after multiplication of at least one of these signals by a constant factor, into traveling wave signals associated with oppositely moving traveling waves, these traveling wave signals appearing at corresponding outputs of the summation circuit. An integration circuit forms time integrals of the traveling wave signals and an evaluation circuit links or processes at least two traveling wave-time integrals into an evaluation function characterizing the fault direction and/or the fault distance from the measuring location or at least a predetermined reference location on the line. The voltage signal channel encompasses two parallel branches, one of which comprises an oscillating circuit having a natural frequency contained in the fault-free line voltage.

Apparatus for localization of a line fault by using traveling wave

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 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.

Growing community of inventors

Niederrohrdorf, Switzerland

Otto Lanz