Abstract: A surge arrester designed for use with lines of 2 kV or less has a housing (10) which, in combination with a cup-shaped gasket (25), an O-ring gasket (45) and a lid (20), seals a varistor element (30) inside against environmental contaminants such as water or pollutants.

Abstract: Apparatus and method for protecting equipment against electrical power surges which is not `ground-centered`. A protection circuit in accordance with this invention comprises at least (a) two input terminals, (b) two fuses in series respectively, (c) a triac which is over-current activated and connected at outputs of the fuses, (d) an over-current sensor in series between one of the fuses and an output terminal, to activate the triac, and (e) a static potential limiter which is overvoltage activated and connected between the triac and a ground terminal. Each fuse is appropriately rated to blow before the activated triac or the activated static potential limiter of the protection circuit are destroyed.

Abstract: A circuit arrangement protects power semiconductor switches against switching overvoltages. The switches can be switched on and off via their control input and form a pair of arms in a power converter. The circuit arrangement includes a comparator which has a downstream analog amplifier with a limiting characteristic curve and is connected in an electrically conductive fashion on the output side to a control input of the power semiconductor switch to be protected, an actual voltage and a predetermined desired voltage of the main terminal of this power semiconductor switch being present across the comparator. The result is a circuit arrangement for protecting against overvoltages, it being possible to dispense with an RCD wiring network for the power semiconductor switches, since very small voltage deviations are detected immediately and the power semiconductor switch is switched off in a controlled fashion.

Abstract: A surge suppressor disconnect protection circuit is coupled to a first surge suppressor electrically coupled to the terminals of an AC source to protect the first surge suppressor from predetermined overvoltages. The circuit includes a relay switch connected in series with the first surge connected to the AC source terminals for rectifying the AC to generate a DC signal. The adjuster filters the DC signal and scales the filtered DC signal. An amplifier is electrically coupled to the adjuster and to and providing a difference signal integrator time constant is electrically connected to the amplifier and produces a signal which is proportional to a length of time the scaled DC signal is greater than the first voltage reference. A comparator is connected to a second voltage reference. The comparator output is electrically coupled to the relay switch which opens the switch contact to set it to a high impedance state when the integrator output signal exceeds the second voltage reference.

Abstract: A current induction arrangement develops a power supply voltage and a measurement signal from current flowing in a circuit path so as to optimize both the energy developed in the power supply and the fidelity of the sinusoidal signal used to measure the waveform in the circuit path. The arrangement includes a capacitor accumulating current to develop a positive voltage with respect to common, a current transformer inducing current from the circuit path and providing an output having a positive induced-current signal component and a negative induced-current signal component. A rectifier circuit is arranged to receive the output from the current transformer, and to produce the positive induced current signal component at a positive output terminal and the negative induced current signal component at a negative output terminal. A first zener diode is connected to receive the positive induced-current signal component, and the circuit permits the positive induced-current signal to charge the capacitor.

Abstract: A ground fault interrupter, operable in a measurement state, is employed with a DC circuit having a DC power source and a load. The DC source supplies DC current to the load along a supply current path and receives DC current from the load along a return current path. The ground fault interrupter comprises a first resistance in series with the supply current path, a second resistance in series with the return current path, and a current interrupter disposed in series with one of the current paths. The current interruptor interrupts the one of the current paths in response to actuation of the current interrupter. The ground fault interrupter further includes a measurement unit for measuring voltage drops across the respective first and second resistances during the measurement state, obtaining a measurement value using a difference between the voltage drops, and comparing the measurement value to a predetermined threshold.

Abstract: A power conditioning device protects sensitive electronics in modern electronic equipment from disruption or destruction caused by transients which can cause both induction and injection currents into the grounding system of the electronic equipment. This device nominally comprises an isolation transformer and a ground impedance between the earth ground connection from a distribution panel and the safety ground connection to the powered equipment. In addition, this device may also comprise a voltage clamping device such as an MOV and a capacitive filter to provide a complete power line conditioner. This device may be used in systems with guarded or driven grounds, or in a system with a high voltage reference to safety ground. In addition, ground conditioning can be added to a Ground Fault Circuit Interrupter (GFCI) to attenuate ground surge currents.

Abstract: A snubber energy recovery circuit for protecting switching devices from current and voltage, which comprises a snubber circuit connected in parallel with a switching device, a recovery path for recovery the energy stored in the snubber circuit, and a constant-current source for maintaining current flowing in the recovery path at a constant value. The snubber circuit is composed of a snubber diode and a snubber capacitor, with one end of the recovery path being connected to the junction point of the snubber capacitor and snubber diode.

Abstract: A three-terminal surge arrestor unit employs air gaps augmented with semiconductors to protect a circuit having two ungrounded conductors. Conductive electrodes and the semiconductors are mounted on a common axis in a sandwich arrangement and secured in fixed relative positions. Two air gap lightning arrestors provide current paths for the respective conductors to ground in response to lightning strikes or other damaging surges, and an equalizer is incorporated in the electrode configuration to establish a current path between the conductors to protect them from an excessive voltage differential. The resulting configuration is a single, three-terminal unit designed to replace multiple unit air gap systems and gas tube arrestors.

Abstract: An insulating substrate has a heat generating resistor and an electrical conductor on its surface. A pair of conductors, such as power or communication leads, are connected to a protected circuit. A rated voltage element and the heat generating resistor is connected in series between the lines. The electrical conductor is connected in series between one of the lines and the protected circuit. When a continuous overvoltage greater than a rated voltage of the rated voltage element develops in the lines, the rated voltage element acts to draw excess current through it and the heat generating resistor. When this current reaches a certain point, heat from the overcurrent in the heat generating resistor ruptures the substrate and the electrical conductor so that both the rated voltage element and the circuit are isolated from the conductors. This protects the protected circuit from destruction of, and consequent loss of protection by, the rated voltage element.

Abstract: An overcurrent protection circuit is provided with a counter which permits a preselected number of reinitiations of current following the detection of an overcurrent condition. Each stoppage of current in response to the detection of an overcurrent condition is followed by a predetermined time delay and a subsequent reinitiation of current. After the predetermined number of reinitiations, current is permanently stopped from flowing between first and second circuit points until a manual reset occurs.

Abstract: An actuator in which an output shaft can be made to stop by a simple structure and in which actuator assured restart of the output shaft can be performed. The actuator comprises a motor, an output shaft provided with an external threading, and a connecting member having an internal threading engaged with the external threading of the output shaft. The actuator further comprises a resilient member for applying a predetermined load to the output shaft when the output shaft reaches the end of its moving range. The connecting member may comprise an internal screw member having a first protrusion formed on an outer surface thereof and a gear member having a second protrusion. When the second protrusion impacts with the first protrusion, a large starting torque is obtained. Further, two PTC thermistors are provided in a protection circuit, each thermistor allows flow of a current in only one direction, so as to prevent a reduction of a starting current.

Abstract: A method and an apparatus for relieving a capacitor of a controlled series compensator as a function of the load on its arrester when high-current line faults occur. The current flowing through the arrester is used to determine its absorbed energy, from which a temperature gradient is then determined as an indicator of a sudden load on the arrester and compared with a limit value. This comparison value is processed, as a function of the determined actual arrester temperature and the measured line current, to yield a control signal. The power converter valve of the controlled series compensator is triggered in response to this control signal in such a way that its equivalent impedance is switched from capacitative to inductive. The number of disconnections required as a result of high-current line faults is thereby considerably reduced, thus greatly increasing availability of the system.

Abstract: An integrated circuit power device includes many cell blocks which are electrically connected in parallel, with each of the cell blocks including at least one cell such as a MOSFET, electrically connected in parallel. A transient responsive current limiting means, such as a resistor/capacitor circuit, is electrically connected to each cell block, so that the leakage current into defective cell blocks is maintained below a predetermined level without limiting the operating speed of the device. An operable integrated circuit power device is thereby obtained, notwithstanding a defective cell block. The circuit resistors are preferably formed using the same mask and material as the gate. The circuit capacitors and common gate electrode are preferably formed using the same mask and material as the source electrode. The use of common materials eliminates the need for extra fabrication steps.

Abstract: The utilization of clusters of two or more metal oxide varistors (MOVs) connected in parallel for suppressing surges and transients. Particular embodiments are disclosed for both grounded and ungrounded power systems. Also disclosed are two-stage and multi-stage uni-directional and bi-directional suppressors. Uni-directional means that the suppressor is intended to be placed between a source and a load for the purpose-of preventing voltage surges and transients from being propagated from the source into the load. Bi-directional suppressors are intended to be placed between a source and a load and provide suppression in both directions simultaneously.

Abstract: In a surge absorber, capable of suppressing a voltage surge and a current surge together without interrupting a signal transmission, an input electrode and an output electrode are spaced apart on the surface of a varistor substrate, and a resistance element is connected between the electrodes. A ground electrode is provided on the reverse side of the varistor substrate so as to face the input electrode with the varistor element therebetween. Thereby, a varistor element is formed by the input electrode and the ground electrode where a voltage surge and a current surge can be suppressed by the resistance element, and where a signal waveform is not weakened by capacitance of the varistor element, and ordinary signal transmission is not interrupted.

Abstract: The present invention relates to solid state surge protectors, having thermally sensitive fusible fail short protection associated therewith, enclosed in a hollow housing which provides three terminals and is specifically designed to be the same volume as gas tube surge arresters presently in use so that it may readily be replaced in any assembly which utilizes a gas tube arrester at the present time.

Abstract: A circuit analyzing system includes a current transformer for extracting current from a phase or neutral conductor of a three phase line, a filter connected to the output of the current transformer and functioning to substantially trap current at the fundamental frequency while substantially passing currents at various harmonic frequencies thereof, and signal processing circuitry connected to the output of the filter to perform various functions with the harmonic frequency current input thereto. Among these functions, as shown in various preferred embodiments, are measurement of the harmonic signal in RMS and conveyance of the output to a display instrument for a user or utility's convenience in monitoring harmonic frequency circuits, which have become more common with the advent of electronic equipment having internal power supplies such as personal computers, work stations, printers, and the like.

Abstract: The reactor switch is provided for switching on and off a reactor (2) in a multiphase electrical high-voltage network. It has switch poles (3) which are arranged phase-by-phase between the reactor (2) and a part of the network containing, a high-voltage line (1). These switch poles (3) in each case contain at least two series-connected switching chambers (11, 12; 13, 14) in parallel with which at least two series-connected varistors (15, 16; 18, 19) are connected. This reactor switch is intended to be capable of disconnecting short-circuits occurring between the reactor switch and the reactor (2) without problems.

Abstract: A device for motor and short-circuit protection in low-voltage plants includes a contact device (3) which is connected in series with a tripping circuit comprising two parallel-connected current branches. One of the branches comprises a first thermistor (1) serving as an overload protective means and connected in series with a second thermistor (2) serving as a short-circuit protective means. The second branch comprises a multi-turn excitation coil (4) which is adapted to influence the contact device (3) for opening thereof at an overcurrent. The resistivity of the two thermistors (1, 2) has a positive temperature coefficient in the temperature range in question. The first thermistor (1) may consist of a ceramic material or electrically conductive polymer composite. The second thermistor (2) consists of polymer composite with a extremely high content of electrically conductive filler and is, in addition, layered.