Abstract: The invention relates to a multi-channel digital oscilloscope having a plurality of analog inputs, circuits for the analog processing of input signals, sampling and digitizing circuits, means for triggering and synchronizing different channels and electrical isolation means. The invention is characterized in that, for N channels, where N is greater than 1 and at least equal to the total number of channels, at least the sampling and digitizing circuits are located between the analog input and the isolation means.

Abstract: A process and apparatus for identification of the direction of rotation of two periodic electrical signals present on two electrical conductors, particularly of a three-phase power system. In this process, the signals are sampled from two conductors by two wires of the test apparatus provided with a connection to ground via a user of the apparatus. The direction of rotation is determined from information provided by the two signals. The direction of rotation is determined during the zero-crossing of the voltage between the two phase signals. The invention can be used in a apparatus for testing of the direction of rotation of the phases of a three-phase network.

Abstract: A procedure to measure the grounding resistances of electrical installations by measuring the loop impedance. According to this procedure, using voltage generator transformers, a current is injected into the loop and this current is measured using current measurement transformers. Two transformers are united into a single transformer, used as impedance transformer, and the loop impedance is established by taking several measurements that allow determining and eliminating parameters of the transformer, by analysis of the measurement results.

Abstract: A procedure to measure the grounding resistances of electrical installations by measuring the loop impedance. According to this procedure, using voltage generator transformers, a current is injected into the loop and this current is measured using current measurement transformers. Two transformers are united into a single transformer, used as impedance transformer, and the loop impedance is established by taking several measurements that allow determining and eliminating parameters of the transformer, by analysis of the measurement results.

Abstract: A multimeter instrument for measuring variables, such as electrical current, voltage, or resistance includes touch-sensitive zones for selection of the variable to be measured. The measurement circuit associated with the variable selected with the aid of touch-sensitive selection zones is activated by the zone selected.

Abstract: A process and apparatus for identification of the direction of rotation of two periodic electrical signals present on two electrical conductors, particularly of a three-phase power system. In this process, the signals are sampled from two conductors by two wires of the test apparatus provided with a connection to ground via a user of the apparatus. The direction of rotation is determined from information provided by the two signals. The direction of rotation is determined during the zero-crossing of the voltage between the two phase signals. The invention can be used in a apparatus for testing of the direction of rotation of the phases of a three-phase network.

Abstract: The invention pertains to a multimeter instrument for measuring a plurality of variables, such as the current or voltage of an electrical signal or the electrical resistance of a circuit, the instrument comprising a plurality of measurement means each associated with a predetermined variable, and device (20) for selection of the variable to be measured.

Abstract: An acquisition process for signal sampling includes high-speed analog signal sampling, storing the samples of the analog signal in a matrix of memory cells, and re-reading the samples from the cells at low speed. Two identical memory devices are provided in each memory cell. One sample of an analog signal is stored in one memory device, and one sample of that signal that is out of phase is stored in the other memory device.

Abstract: The invention concerns an acquisition process by analog signal sampling.

Abstract: A polarized bistable electromagnetic relay arrangement comprising at least two monostable instantaneous electromagnetic relay devices with a L-shaped yoke, a permanent magnet disposed between both relay devices so that one magnetic pole be magnetically connected by polar masses to both yokes of the relay devices and polar masses magnetically connect the other pole of the magnet to both blades whereas the magnetic circuits of both relay devices are designed so that the magnetic flux produced by one energized coil passes in series through both blades while superposing themselves to the magnetic flux produced by the permanent magnet.