Abstract: In an apparatus for EMC testing of electrical devices, conductors are arranged at opposite sides of a chamber of conductive material at a spacing from and parallel to the chamber walls. These conductors form a symmetrical double line and are fed out of phase at one end by a radio frequency source. They are electrically connected to the chamber walls at the other end via terminating impedances.

Abstract: An interface having nine connections between a probe and test and measurement equipment includes a fixed voltage source located in the test and measurement equipment, which delivers through a first connection a positive fixed voltage, and through a second connection a negative fixed voltage. A voltage-programming resistor located in the probe produces a signal that is delivered from the probe through one of the connections to the equipment to control a programmed voltage source. The programmed voltage is delivered as a positive programmed voltage through one pin and as a negative programmed voltage through a second connection. A probe identification resistor is located in the probe. An ohmmeter in the equipment measures the resistance of the probe identification resistor through one of the connections.

Abstract: An apparatus is disclosed for testing concrete having an unknown water/cement ratio and an unknown compressive strength. The apparatus includes a transmitter assembly for transmitting microwave signals at one or more predetermined frequencies. A receiver assembly receives each microwave signal reflected from the concrete under test. The reflected microwave signals, together with the transmitted microwave signals, are used to determine a reflection coefficient magnitude for the particular microwave frequency. A processing unit uses the reflection coefficient magnitude to determine a value related to concrete strength. In one embodiment, the processing unit relies on a logarithmic function that correlates the reflection coefficient magnitude and a water/cement ratio. A value related to the compressive strength of the concrete can also be obtained using the value of the water/cement ratio or the value of the reflection coefficient magnitude.

Abstract: Prior to beginning a dielectric withstand (leakage current) or insulative impedance test, but after applying the high voltage that will be used in the test, the temporary charging currents resulting from application of the high voltage are measured and analyzed to determine if the test sample is properly connected to the test apparatus. If no charging currents are measured, or if the insulation resistance is too high, then it is determined that the test sample is not properly connected and the test is terminated.

Abstract: A device for sensing electric discharges in a test object with at least two electric connection conductors comprises transducer equipment and evaluation equipment. The transducer equipment comprises at least one transducer for direction-sensitive sensing of current pulses through the connection conductors by sensing a magnetic field, generated by the current pulses, and the polarity thereof. The transducer delivers a transducer signal to the evaluation equipment in dependence on said current pulses and their direction. The evaluation equipment generates, in dependence on received transducer signals, an indicated signal indicating an electric discharge in the test object.

Abstract: A method and device for testing the quality of a ground path, particularly although not exclusively for a telecommunications system. The device has terminals for connection to respective lines, such as tip and ring. A terminal is provided for connection to the local ground. Voltage-sensitive switches of increasing threshold voltage are alternatively connected between the local ground and each of the tip and ring lines via a rotary or other selector switch and the terminals. Current will flow if the local ground potential exceeds the threshold voltage of the voltage sensitive switches. A device responsive to mains frequency, e.g. a butt-in head set, provides an audible sound (mains hum) indicating the ground potential rise exceeds the threshold of the selected voltage-sensitive switch.

Abstract: A system for determining the fundamental frequency of a digitized AC signal is disclosed. Each signal zero crossing is detected, and in response to each zero crossing, two discrete impulses are generated. In response to the train of generated impulses, the system determines the fundamental frequency of the AC signal.

Abstract: A method of detecting the presence of an electric cable, the electric cable including conductive armoring and a conductive core that is electrically insulated from the armoring. In the method, the armoring is connected to ground, and a current pulse is emitted over the armoring by way of a current injector device connected to ground so that the return of the pulse to the injector device takes place via ground. The presence of the electric cable is detected in the proximity of a reception point by detecting, at the point, a signal that is representative of the pulse, by way of a detector.

Abstract: A male terminal inspecting tool of a connector (11) has a connector holder (2), a pin receiver (3) which is movably arranged at a position opposite to the connector holder (2) and has a conductive pin (4) inside it, and an operation lever (6), characterized in that a hole or slit (15) having the smallest dimension into which the front end portion of the male terminal (19) of the connector (11) can inserted is provided in the vicinity of the conductive pin (4) in the pin receiver (3).

Abstract: A measuring device displays waveforms representative of electrical signals and includes a selector, at least one input terminal, and a graphical display. The graphical display is suitable to view a waveform thereon. The measuring device receives an electrical signal from the input terminal and displays a first waveform on the graphical display representative of the electrical signal. The selector is selectable to one of a plurality of positions and the measuring device selects a set of waveform data in response to each of the positions. The measuring device displays a second waveform on the graphical display representative of the waveform data.

Abstract: The measuring device is intended for a metal-enclosed, gas-insulated high-voltage installation. It contains at least one Rogovski coil (10), which is arranged in an enclosure tube (3), filled with insulating gas, of the metal enclosure and serves to detect the current in a current-carrying conductor (9), led through the enclosed tube (3), and a measuring electrode (11), which surrounds the conductor (9) and serves to detect the voltage of the conductor (9). The current conductor (9) is rigidly connected to a current-conducting cast armature (13) of an insulator (14) fastened to the enclosure tube (3). In the measuring device according to the invention, a defined field geometry is maintained in the interior of the enclosure tube (3) even over long periods and under changing loads. Consequently, the sensors, in particular the voltage sensor containing the measuring electrode (11), can transmit output signals of high measuring accuracy.

Abstract: A method and apparatus for measuring sheet resistance and thickness of thin films and substrates. A four-point probe assembly engages the surface of a film on a substrate, and the thickness of the substrate is determined from the point of contact between the probes and film. A measuring apparatus then outputs a voltage waveform which applies a voltage to probes of the probe assembly. An inverter inverts the voltage and provides the inverted voltage on another probe of the probe assembly, thus inducing a current in these probes of the four point probe and through the surface of the film. Two other probes measure a voltage in the film created by the current. The voltages on the current probes provide a voltage close to zero at the other probes, thus allowing these other probes to measure voltages with greater precision. The current created by the voltage waveform and the voltage created across the inner probes are measured for each voltage level of the waveform.

Abstract: A battery test contact clamp assembly is set forth. In one embodiment, upper and lower printed circuit boards are spaced apart on four corner located mounting rods of conductive metal. The four rods pass through one of the boards and are held to it by a set of detents and four hubs located at corners to thereby define a rectangular structure where the boards can move closer together or further apart. Frictional mounting hubs are used for the four rods. They are connected electrically in a circuit which involves contact assemblies on the two boards and they are aligned with battery terminals for contact to thereby define an electrical flow path with a test circuit. The contacts are aligned with the battery terminals. Alternative embodiments include two boards with multiple conducting rods there between and they are connected in several independent test modules. Another embodiment features two test contacts mounted on a common board for testing of batteries having two terminals at one end of the battery.

Abstract: In a measuring system for an enclosed high-voltage switchgear having at least two poles, each of which is phase segregated, and with sensors for dielectric noise and a detector device connected to them for outputting a signal in the event of an noise, a time comparator is provided that blocks the output of a signal if the time difference between two noise signals from sensors of different phases is less than a certain interval of time, in particular an adjustable interval.

Abstract: A method and apparatus for determining specific material characteristics of plastic materials in which the plastic material is disposed between electrodes of a capacitive sensor and the impedance is measured and compared to a reference value, preferably stored in a computer.

Abstract: The hand held circuit tester includes a hollow handle. A probe extends from one end of the handle. First and second leads extend from the other. An LED carrying circuit board is situated within the handle. One end of the circuit board is connected to the probe by a spring. The other end is connected to the leads. A "U" shaped collar is received within slots in the circuit board in a position perpendicular to the plane of the circuit board. The collar edge abuts the edge of one of the handle parts to stabilize the circuit board relative to the handle.

Abstract: The invention consists of a system to compensate for the parasitic signal induced by a parasitic impedance in the signal path. An auxiliary signal, outside of the frequency band of the desired signal, is introduced to evaluate the effects of the parasitic impedance. A compensating signal is then generated by simulating the effects of the parasitic impedance on the desired signal. Those simulated effects are then superimposed over the normal signal path with a phase adjusted to eliminate the effects of the parasitic impedance on the total resulting signal.

Abstract: A device for measuring the levitation force of a high temperature superconductor sample with respect to a reference magnet includes a receptacle for holding several high temperature superconductor samples each cooled to superconducting temperature. A rotatable carousel successively locates a selected one of the high temperature superconductor samples in registry with the reference magnet. Mechanism varies the distance between one of the high temperature superconductor samples and the reference magnet, and a sensor measures levitation force of the sample as a function of the distance between the reference magnet and the sample. A method is also disclosed.

Abstract: The present invention relates to a process for determining harmonic oscillations of a fundamental component of an electrical signal, wherein the signal is sampled with a sampling frequency corresponding to a multiple of the fundamental component's frequency. The sampled values of the signal are subjected, after analog-to-digital conversion, to a discrete Fourier transformation to determine the harmonic oscillations. The sampling is performed with a non-integer multiple of the frequency of the fundamental component and the discrete Fourier transformation is performed while the frequency resolution is increased over several periods of the fundamental component to determine the harmonic oscillations.

Abstract: The inductance-change detection apparatus comprises an inductance-change converter that converts inductance-change in coils into voltage to output, a reference-voltage generator that generates and outputs a predetermined reference voltage, a frequency characteristic adder that adds a frequency characteristic similar to that of the converted voltage converted by the inductance-change converter to the reference voltage, a reference-voltage compensator that varies and compensates the frequency spectrum of the reference voltage containing the added frequency characteristic, in parallel in the direction of amplitude, corresponding to a parallel variation of the frequency spectrum of the converted voltage in the direction of amplitude, and an inductance-change detector that compares the converted voltage with the compensated reference voltage to detect inductance changes in the coils.