Abstract: This invention concerns a method and devices for calibrating a partial discharge measuring device and for locating faults on cables. In the method, calibration signals, which can include a band-limited white noise, are used with a periodically repeated signal course. By averaging over a predetermined period duration (T) of the calibration signal, it is possible, in the case of a partial discharge measurement, to recalibrate the measuring device continuously during the measurement, and additionally on cables to determine the fault location with great precision.

Abstract: An apparatus and method for the measurement of a resistance of a switching contact of an electrical circuit breaker. A first resistance value across the circuit breaker is determined while the circuit breaker is grounded at both sides and the switching contact is closed. Further, a second resistance value across the circuit breaker is determined while the circuit breaker is grounded at both sides and the switching contact is open. The resistance of the closed switching contact is then determined based on the first resistance value and the second resistance value.

Abstract: In a method, operation of an electric power system which has a power utility automation system (1981-1984, 1991-1994) is monitored. The power utility automation system (1981-1984, 1991-1994) comprises a plurality of intelligent electronic devices (IEDs) (1981-1984, 1991-1994) communicating via a communication network. During operation of the electric power system, properties of the electric power system are monitored, the monitored properties comprising monitored data messages which are transmitted by the plurality of IEDs (1981-1984, 1991-1994) over the communication network. The monitored data messages are evaluated based on configuration information for the power utility automation system (1981-1984, 1991-1994) to detect a critical event. An alert signal is generated in response to detection of the critical event.

Abstract: This invention concerns methods and devices for calibrating a partial discharge measuring device and for locating faults on cables. In the method, calibration signals, which can include a band-limited white noise, are used with a periodically repeated signal course. By averaging over a predetermined period duration (T) of the calibration signal, it is possible, in the case of a partial discharge measurement, to recalibrate the measuring device continuously during the measurement, and additionally on cables to determine the fault location with great precision.

Abstract: A test device (1) for testing power engineering equipment comprises at least one connection socket (4) which is electrically connected to an overvoltage protection arrangement (2). The overvoltage protection arrangement (2) comprises at least one overvoltage protection element (5) and is configured such that the at least one overvoltage protection element (5) is exchangeable.

Abstract: The present invention relates to a measuring device (10) for measuring a resistance of a switching contact (5) of an electrical circuit breaker (1). The measuring device (10) comprises a high-current generating unit (11) for generating a measurement current for the resistance measurement, and a measuring unit (12) for registering a measurement signal at the circuit breaker (1) during the opening or closing of the switching contact (5), and for determining a time-based resistance course of the switching contact (5) during opening or closing, in dependence on the measurement current and the measurement signal.

Abstract: Measuring device for checking an electrical circuit breaker includes a current generating unit designed to generate a measurement current for a continuity measurement of a switching contact of the circuit breaker. The measuring device furthermore includes a measuring unit for registering a measurement signal at the circuit breaker, an energy supply unit for supplying a control drive of the circuit breaker with electrical energy, and a control unit, which has a timer. The control unit is able output to the control drive, via the control output, a signal for opening or closing the circuit breaker, and to determine a time-based switching behaviour of the circuit breaker in dependence on the measurement signal. Further, the control unit is designed, in the case of the circuit breaker being closed, to determine the resistance of the switching contact in dependence on the measurement current and the measurement signal.

Abstract: A method and a device for determining a humidity content of an insulation of a transformer, the insulation having a liquid. At least one dielectric property of the insulation is measured, an uncorrected humidity content of the insulation and a conductivity of a liquid which is included in the insulation is derived from a model of the insulation, said model being chosen depending on the measured dielectric property of the insulation, and the humidity content of the insulation is corrected by means of the conductivity.

Abstract: Method and device for monitoring the status of a sheath voltage arrester of a cable system, a verification signal being supplied to a measuring loop which comprises the sheath voltage arrester and a measurement signal which is subsequently produced in accordance with the frequency-dependent impedance of the sheath voltage arrester being measured at the measuring loop in order to establish the status of the sheath voltage arrester by evaluating the measurement signal.

Abstract: The present invention relates to a method for determining partial discharges at an electrical component (10). In the case of the method, an electrical signal that comprises partial discharge pulses due to the partial discharges at the electrical component (10) is detected. Through filtering of the electrical signal by means of n filters (18-20) having n differing filter characteristics, n filtered partial discharge signals are generated. Respectively one of the filtered partial discharge signals is assigned, respectively, to one of the n filters (18-20), n being greater than or equal to two. Finally, the partial discharges are determined by linking the n filtered partial discharge signals.

Abstract: This invention concerns a method and devices for calibrating a partial discharge measuring device and for locating faults on cables. In the method, calibration signals, which can include a band-limited white noise, are used with a periodically repeated signal course. By averaging over a predetermined period duration (T) of the calibration signal, it is possible, in the case of a partial discharge measurement, to recalibrate the measuring device continuously during the measurement, and additionally on cables to determine the fault location with great precision.

Abstract: This invention concerns a system for monitoring a transformer which comprises multiple terminals. The system includes multiple measuring devices and a transformer monitoring device. Each measuring device is arranged adjacently to a terminal of the transformer. Each measuring device includes a housing, a processing unit, a terminal to connect the processing unit to a sensing means to sense an electrical magnitude at the terminal of the transformer, and a data transmission terminal to transmit data between the processing unit and the transformer monitoring device. The transformer monitoring device, which is connected to the multiple measuring devices, is designed to determine, from a combination of the data from the multiple measuring devices, a present state of the transformer.

Abstract: A method for testing a protective device as well as a correspondingly configured protective device and test device are provided.

Abstract: A method and an apparatus for testing a power engineering device, for example a high-power transformer, are provided. A test signal is applied to the power engineering device, and this test signal, starting from an initial value, rises steadily and monotonically to a predetermined final value (U0), and retains this final value (U0) over a predetermined time interval.

Abstract: A method and a device for determining a humidity content of an insulation of a transformer, the insulation having a liquid. At least one dielectric property of the insulation is measured, an uncorrected humidity content of the insulation and a conductivity of a liquid which is included in the insulation is derived from a model of the insulation, said model being chosen depending on the measured dielectric property of the insulation, and the humidity content of the insulation is corrected by means of the conductivity.

Abstract: Method and device for measuring a dielectric response of an electrical insulating system, wherein a first measurement result is determined by a frequency domain method and a second measurement result is determined by a time domain method, whereupon the first measurement result and the second measurement result are combined to form an overall measurement result as the dielectric response. Standard types of measurement methods, for example the FDS and PDC methods, may be used as measurement methods for the frequency domain and the time domain.

Abstract: Method and device for measuring a dielectric response of an electrical insulating system, wherein a first measurement result is determined by a frequency domain method and a second measurement result is determined by a time domain method, whereupon the first measurement result and the second measurement result are combined to form an overall measurement result as the dielectric response. Standard types of measurement methods, for example the FDS and PDC methods, may be used as measurement methods for the frequency domain and the time domain.

Abstract: Testing a transformer by applying to the transformer a test signal, the frequency of which may be lower than the nominal frequency of the transformer. The voltage of the test signal may also be lower than the nominal voltage of the transformer. A number of frequency-dependent parameters are measured, particularly the eddy current resistance and the hysteresis curve of the transformer, in order to derive a simulation model which simulates the behavior of the transformer at different frequencies. Using this simulation model, it is possible to predict operating parameters of the transformer, such as the terminal voltage on the secondary and the terminal current in the secondary, during operation with a frequency deviating from the frequency of the test signal, particularly during operation with the nominal frequency of the transformer.

Abstract: Testing a transformer by applying to the transformer a test signal, the frequency of which may be lower than the nominal frequency of the transformer. The voltage of the test signal may also be lower than the nominal voltage of the transformer. A number of frequency-dependent parameters are measured, particularly the eddy current resistance and the hysteresis curve of the transformer, in order to derive a simulation model which simulates the behavior of the transformer at different frequencies. Using this simulation model, it is possible to predict operating parameters of the transformer, such as the terminal voltage on the secondary and the terminal current in the secondary, during operation with a frequency deviating from the frequency of the test signal, particularly during operation with the nominal frequency of the transformer.

Abstract: There is described a fully automatic portable testing device which can be used generally for testing test-pieces to be operated at high voltages and/or high currents, such as current or voltage transducers or transformers for example. For this purpose, the portable testing device comprises a switched-mode power amplifier (3) whose output is connected to a matching transformer (4-7) having a plurality of secondary windings (5-7), which can be changed over. The test-piece on which measurements are to be made is in each case removably connected to the secondary windings (5-7) of the matching transformer. The portable testing device also comprises a control which in particular may have a digital signal processor (8) and/or a controller or computer (9) and which on the one hand controls the power amplifier (3) in a purposive way and preferably also performs an automatic changeover of the secondary windings (5-7) of the matching transformer, in order to generate a desired testing signal.