Abstract: An electronic tripping device for a circuit breaker contains circuitry for simulating the response curve of a fuse. This circuitry can be controlled by a single setting mechanism representing the nominal currents or rated currents of fuses. This improves the coordination of protection in sophisticated power supply equipment containing both circuit breakers and fuses. Tripping devices equipped with microprocessors or operating in an analog fashion can be configured for the mode of operation. The new protection system achieves particularly safe operation for the user in that the setting mechanism is combined with a rating plug for the “fuse” mode, thus directly setting the tripping device to one current value. In a manner similar to a true fuse, consequently, the setting mechanism is provided with appropriate labeling. The simulated curves may contain a point of inflection below a limit in a lagging manner, to increase the nominal switching capacity and selectivity limit of a circuit breaker.

Abstract: A circuit arrangement is described for monitoring an electronic tripping device for low-voltage switches having a microprocessor device which, in conjunction with a digital-analog converter, evaluates an overcurrent so that line power supply system. The microprocessor device (MPE) has a zero crossing comparator with which a constant test current pulse is transmittable, at zero crossings, to the electronic tripping device via an additional current transformer winding to measure the amplitude. In the case of deviations from the setpoint value, (re)calibration or actuation of the line tripping contacts, with an alarm signal being emitted, takes place.

Abstract: An undervoltage circuit breaker has an electromagnet for triggering a switching device and a driver circuit that supplies power to the electromagnet. The driver circuit contains a pulse generator for generating a holding current for the electromagnet and a capacitance dimensioned so that delayed triggering of the electromagnet is possible. Due to the variable pulse duty factor of the pulse generator, the energy content of the capacitance is utilized favorably. An elevated operating voltage can also be selected and therefore a smaller capacitor may be selected to advantage.

Abstract: A circuit configuration for supplying power to electronic tripping devices from a current-transforming device. A switched-mode power supply unit, in particular a choke/step-up transforming device having a pulse-width voltage control, is connected downstream of a charging capacitor. Once a set point of the output voltage at an output capacitor is reached, only a very high pulse duty factor is provided. Particularly, maximum power point control is provided during an initial charging phase. Circuit configurations of this kind serve the power supply of overvoltage tripping devices in low-voltage and medium-voltage systems.

Abstract: A circuit-breaker with current transformers and with an electronic tripping device having a housing contains a data storage device for characteristic values of the current transformers and the circuit-breaker. The data storage device provided with interfaces to the electronic tripping device and to the current transformers is detachably mounted on the outside of the housing of the tripping device.

Abstract: A method of determining the ground-fault current flowing in a multi-phase circuit is based on the use of standard current transformers having iron cores for the phase conductors and the neutral conductor. Allowance is made for the current-dependant linearity error of the current transformers by subtracting the product of the highest phase-current and associated error from the vectorial sum of the currents. This results in a single-sided position of the tolerance band of the measured ground-fault current and prevents spurious tripping.

Abstract: A voltage transformer with increased electric strength has a resistance divider made of ohmic resistances as well as a working amplifier and an inductive transformer. The secondary side of the inductive transformer forms the undervoltage side of the voltage transformer. Since high electric strength resistances are cheap to obtain, this voltage transformer is particularly useful in cases where an inductive voltage cannot be used because of its size and price, for example in low voltage power switches with voltage display or voltage measurement.

Abstract: In a hydropneumatic accumulator, the gas volume contained therein is monitored by measuring the volume increase in the hydraulic fluid, which takes place during a pressure increase at a given minimum pressure. Moreover, for monitoring purposes, the hydraulic pressure is measured and a signal transmitted at insufficient gas volume as a function of the volume increase and the pressure increase. In order to obtain reliable signals concerning the filling state of the accumulator at all ambient operating temperatures, the temperature of the environment and the gas volume is detected, a standard value for the volume increase proportional to the ratio of the gas temperature to the minimum pressure determined and the volume increase causing the pressure increase compared to this standard value.

Abstract: In a circuit arrangement for measuring currents at high potential, a capacitor, charged in accordance with the current to be measured, is shunted by a light emitting diode which generates a light pulse sequence with a frequency proportional to the current. In series with the diode is a switching element with a control terminal, to which the output of a control device is connected. The input of the control device is connected to a threshold arrangement disposed parallel to the capacitor and the supply terminals of the control device are connected to the capacitor.

Abstract: The invention is directed to a control electrode for high-voltage apparatus which alters the electric field in the vicinity of the voltage-carrying parts. The control electrode includes a formed body of a conductive plastic foam material. The control electrode is suitable, for example, for multipole medium-voltage switching apparatus wherein the pole spacing can be reduced with the air of control electrodes of the invention.