Abstract: Methods and devices for locating partial discharges in electric cables with a high-voltage source coupled to the cable to be tested, a decoupling unit connected to an end of the cable and a data-processing system that is connected via a sensor unit to the decoupling unit and that detects a partial discharge or partial discharges when they exist from the sensor signals. The methods and devices particularly distinguish themselves by a short evaluation duration for the locating process. This is done by detecting events, parameterizing the events identified as pulses, formation of pairs of the events identified as pulses and parameterized, classification of the event pairs, assignment of a partial discharge from the classification and determination of the location of the partial discharge(s) from the different in transit times between the respective partial discharge and its accompanying reflection.

Abstract: The invention relates to circuit arrangements for cable checking, cable testing, cable diagnosis and/or cable fault localization with a voltage source having a first voltage multiplier for a positive voltage and a second voltage multiplier for a negative voltage current sources that are connected to one another in combination with the voltage multipliers to generate a test voltage over the load impedance of the cable to charge and discharge the load capacitance of the cable and a control device that is interconnected with the voltage source and the current sources and devices with a circuit arrangement of that type. The circuit arrangements distinguish themselves, in particular, by the fact that arbitrary voltage curves of different amplitudes can be generated through the cable as the impedance acting as the test specimen.

Abstract: The invention relates to methods and devices for locating partial discharges in electric cables with a high-voltage source coupled to the cable to be tested, a decoupling unit connected to an end of the cable and a data-processing system that is connected via a sensor unit to the decoupling unit and that detects a partial discharge or partial discharges when they exist from the sensor signals. The methods and devices particularly distinguish themselves by a short evaluation duration for the locating process. This is done by detecting events, parameterizing the events identified as pulses, formation of pairs of the events identified as pulses and parameterized, classification of the event pairs, assignment of a partial discharge from the classification and determination of the location of the partial discharge(s) from the different in transit times between the respective partial discharge and its accompanying reflection.

Abstract: A method and an apparatus are provided to reduce or eliminate interference signals that have been additively superimposed on a useful signal for locating a cable sheathing fault of a buried electrical cable. A correction unit includes a filter, a delay device and/or a DC component estimator. The correction unit automatically determines a transient interference signal and a DC offset voltage component that have been superimposed on the useful signal as received in an input signal of the correction unit, and then subtracts these determined interference signals from the input signal to provide the interference-free or interference-suppressed useful signal as the output.

Abstract: A method and an apparatus provide targeted guidance for a user to locate and trace-out the path of a buried electrical cable, and to locate a cable fault along the cable. A current pulse is applied to the cable, whereby a magnetic field is generated around the cable and an acoustic signal is emitted from the cable fault. The apparatus detects and measures magnetic field information to locate the cable. The apparatus measures a time delay between detecting the magnetic signal and detecting the acoustic signal. By comparing successive time delays at successive measuring positions, a relative proximity to the cable fault is determined. The cable location information and the cable fault distance information are combined to produce a direction indication for the user. Tracing the cable layout and determining the cable fault location can be carried out in a single procedure using a single apparatus.

Abstract: An apparatus for testing a cable or other capacitive load object with a VLF alternating cosine square, rectangular or trapezoidal test voltage, includes one or two DC voltage sources and a switching arrangement controlled by a measuring and control unit, to produce the test voltage with alternating switched polarity. The apparatus further includes a choke coil serving as an energy store, which is controlled by a switching element to be activated if the voltage/time slope arising during the switch-over after a respective half-wave of the test voltage falls below a defined threshold value.

Abstract: A measuring apparatus is connected to a cable to perform testing and diagnosis of the cable. The measuring apparatus includes a voltage source, a resistance, a switch, and an inductance forming a charging circuit, and two anti-parallel thyristors or switched diodes together with the inductance forming a series resonant circuit loop. The apparatus produces a low frequency alternating voltage signal train including a low frequency test signal followed by a low frequency diagnostic signal. The diagnostic signal is a damped decaying signal oscillation in the resonant circuit connected to the test cable. At least one of the signals is bipolar. Both cable testing and cable diagnosis can be performed using the same single measuring apparatus in a single measuring procedure.

Abstract: An apparatus including a portable receiver with an acoustic sensor and a magnetic field sensor is adapted for locating a fault in an underground electrical line by evaluating ground-borne acoustic signals and electromagnetic signals emitted from a succession of sparking arc-overs caused at the fault location by voltage pulses fed into the electrical line. The apparatus further includes an arrangement for eliminating interference noises from the acoustic signals, wherein the acoustic received signals are delivered to and stored in a memory, and then a respective acoustic signal is processed with reference to or in combination with a previous stored acoustic signal by a processing algorithm in a processing unit so as to reduce or suppress the acoustic interference noises in the acoustic signals. Start time points of the individual acoustic signals are synchronized with reference to associated electromagnetic signals. A result of the processing algorithm is supplied to an evaluating unit.

Abstract: A method and an apparatus are provided to reduce or eliminate interference signals that have been additively superimposed on a useful signal for locating a cable sheathing fault of a buried electrical cable. A correction unit includes a filter, a delay device and/or a DC component estimator. The correction unit automatically determines a transient interference signal and a DC offset voltage component that have been superimposed on the useful signal as received in an input signal of the correction unit, and then subtracts these determined interference signals from the input signal to provide the interference-free or interference-suppressed useful signal as the output.

Abstract: An electrical pulse fed into an electrical cable, e.g. a power transmission or distribution cable buried underground, produces an acoustic signal, e.g. an arc-over or discharge noise, at a fault in the cable. This acoustic signal is detected and used to locate the fault. But the acoustic signal has interference noise superimposed on it, which makes it difficult to identify the acoustic signal in the noise-burdened received signal, and thus also makes it difficult or impossible to accurately locate the fault. To minimize or avoid the influence of interference noises, the relevant acoustic signal is identified in the received signal by comparing the received signal with predetermined sample data, such as signal patterns, characteristics or characteristic sets.

Abstract: A voltage pulse is transmitted into a test object, and returned reflection pulses are evaluated to determine the location of a fault in the test object. The return signal includes a reflection from the fault and undesired interfering reflection pulses, which are removed or compensated-out from the return signal to produce a corrected pulse diagram. A circuit arrangement for this includes a bi-directional coupler, a separation filter, a measured signal detection circuit with two input channels, a memory storing a database, a computer processor, and a measured signal evaluation unit. A method in this regard includes a first step of measuring the input impedance of the test object, and a second step of measuring the return signal pulses, transforming the return signal to the frequency domain, compensating the frequency domain data to remove interference, transforming the data back to the time domain, and representing or evaluating the pulse diagram.

Abstract: An apparatus including a portable receiver with an acoustic sensor and a magnetic field sensor is adapted for locating a fault in an underground electrical line by evaluating ground-borne acoustic signals and electromagnetic signals emitted from a succession of sparking arc-overs caused at the fault location by voltage pulses fed into the electrical line. The apparatus further includes an arrangement for eliminating interference noises from the acoustic signals, wherein the acoustic received signals are delivered to and stored in a memory, and then a respective acoustic signal is processed with reference to a previous stored acoustic signal by a processing algorithm in a processing unit. Start time points of the individual acoustic signals are synchronized with reference to associated electromagnetic signals. A result of the processing algorithm is supplied to an evaluating unit.

Abstract: A method and apparatus for the location and indication of cable splices and cable faults is disclosed. An audio frequency generator can be coupled to a cable under test and the magnetic field generated by the cable can be monitored by a receiver. A receiver includes at least two antenna coils situated to detect orthogonal components of the magnetic field. From test values measured at various test points along the cable route, a degree of inhomogeneity of the magnetic field along the cable route can be determined and displayed. Location of a cable fault and cable splice is then apparent in the display.

Abstract: A procedure and a system for the evaluation of the quality and/or efficiency of a cable or a cable segment by a current measurement is disclosed. This is achieved by supplying between the core and the screen of a cable a voltage with alternating polarity and rectangular shape. The periodic duration' of this voltage is selected in a way so as to permit the current measurement of the charge current shortly before a polarity reversal, providing a current value equal to the leakage current.

Abstract: A procedure and a system for the evaluation of the quality and/or efficiency of a cable or a cable segment by a current measurement is disclosed. This is achieved by supplying between the core and the screen of a cable a voltage with alternating polarity and rectangular shape. The periodic duration' of this voltage is selected in a way so as to permit the current measurement of the charge current shortly before a polarity reversal, providing a current value equal to the leakage current.

Abstract: A line locating device and method that is capable of determining the location of a line even when a significant amount of transmitted signal is coupled to neighboring lines. A device according to this invention includes a transmitter that couples a transmitted signal onto a metal line where the transmitted signal is a first signal having a carrier frequency modulated with second signal of a lower frequency. The device also includes a receiver that receives a received signal from the metal line and evaluates the signal in terms of period and polarity to determine an incoming signal or an outgoing signal. The receiver addresses an appropriate signaling unit in response to the incoming signal or the outgoing signal.

Abstract: Hand-held transmitting and/or receiving apparatus, including a housing made of electrically non-conductive material, an electric circuit positioned within the housing, an electrical ground plane positioned within the housing, an antenna resonator element extending approximately parallel to the ground plane and having a first free end and a second end electrically connected by a ground connector to the ground plane and an arrangement for connecting the ground plane and the resonator element to the electric circuit. The resonator element, the ground plane and the ground connector are positioned about and fixed to a dielectric body positioned inside the housing. This antenna is easily manufactured and reduces the influence of mechanical tolerances and mechanical and thermal influences on the electrical parameters of the antenna.

Abstract: The invention is directed to a system and process operating on an air-standard cycle either to cool or heat a room. The system may be advantageously employed to cool or heat relatively small areas or rooms, particularly driver's cabins in locomotives and the like. In cooling operation, outside air is expanded in a turbine, cooled below ambient, and introducted into a heat exchanger. Air from the room to be cooled is introduced into the heat exchanger and heat is removed therefrom. Suitable valves are provided to change the operation of the heat exchanger to that of a regenerator and to direct the flow of air accordingly. Specifically, air heated by compression in the compressor is directly introduced into the room and air leaving the room is passed through the regenerator/heat exchanger and released into the atmosphere.

Abstract: A process used to locate cable faults, in particular to locate non-burnout cable faults in the vicinity of branched cables. The pulse reflection method is used and a capacitor is charged and then discharged across a spark gap by means of spark-over at a fault in the cable. Simultaneously with a main capacitor in an impulse wave generator, a second pulse capacitor is discharged into the cable by means of a short circuit switch. The resulting reflection wave is input via a decoupler into a first channel of a digital storage unit. After opening the short circuit switch, the main capacitor in the impulse wave generator and the second pulse capacitor are again charged and then again discharged into the faulty cable by closing the main switch. The pulse capacitor is discharged by means of a plasma-triggered spark gap. The spark gap is triggered by the charge of the impulse wave generator.

Abstract: A process and apparatus for regulating the quantity of fresh air in high-speed trains by means of pressure-wave valves. A signal for adjusting a drive unit is determined from the passenger count and outside temperature. This drive unit causes a stop fork to move into a flap stop position of the valve in the "open" operating mode so that the required amount of fresh air can be supplied. The process according to the invention results in a considerable saving on energy, since only the absolutely necessary amount of fresh air need be heated or cooled and the period of time in which ventilation can be used rather than cooling is lengthened.