Abstract: The interface card fixedly secured to the circuit breaker supplies information representative of the circuit breaker type and rating to a standard removable trip device. It comprises for example resistances designed to be connected in parallel to a resistance of a divider bridge defining in the trip device the instantaneous tripping threshold, modifying this threshold automatically according to the circuit breaker type and rating. The interface card can also supply the trip device with information representative of the rated current flowing in the primary winding of the current transformers fixedly secured to the circuit breaker.

Abstract: A protective relay communication interface includes a transformer having primary windings arranged as, at least two, sets of opposed windings. The interface is connected to a local relay sensing a current at that point on a power line to be protected. The interface is also connected to a communication link to a remote relay sensing the current at a remote position on the power line. It is by this communication link that signals representative of the sensed currents are transmitted from each relay to the other. A local signal from the local relay is passed through part of, but not all of, the primary windings inducing a corresponding signal in the secondary windings of the transformer which is transmitted to the remote relay via the communications link. A received remote signal from the remote relay is passed via at least two mutually opposed sets of the primary windings to the local relay.

Abstract: An ON-OFF control of a clutch-brake for a press machine, having fail-safe operation. The clutch-brake drive control is provided by turning double solenoid valves on and off. Two lines of drive control signal generators output drive control signals to semiconductor elements when a running command pulse signal is recognized as valid. A bus collating circuit forcibly cuts off AC power supplies of solenoid driving circuits when synchronization and coordination of the operation of each of the lines are checked and found not in coordination. Two lines of fault detecting circuitry forcibly cuts off the AC power supplies of the solenoid driving circuits by automatically detecting a fault of the semiconductor elements.

Abstract: The invention is a self-terminating helper flip-flop buffer circuit pertinent to a dynamic random access memory (DRAM) or static random access memory (SRAM) device. The invention turns off a device which is sourcing current to pull the data line low. The device is turned off when the potential on the low data line has transitioned to the trip point of the output data latch. The circuit of the invention senses the transition and provides the self terminating signal to the current source.

Abstract: Metal oxide varistors are connected in parallel with grounded capacitors to oad outlet terminals coupled to a power source through inductor coils forming a low pass filter with the capacitors to delay propagation of a voltage increasing transient pulse to the power source until ground shunting paths of low resistance are developed in the varistors. Electromagnetic shielding partitions the inductor from the capacitors and varistors within a power outlet box mounting the load outlet terminals to prevent interference with absorption of transient energy by the varistors during the delay in establishing the ground shunting paths.

Abstract: An overvoltage protective device for a series capacitor (C) has a main spark gap and a first auxilary spark gap, arranged adjacent thereto, for ignition of the main spark gap. A second auxiliary spark gap is arranged in association with the first auxiliary gap for ignition thereof. The first and second auxiliary spark gaps are connected between one of the electrodes of the the main spark gap and a voltage divider which comprises resistors (R1, R2, R3 ) and a varisistor (VR1) . When the knee voltage of the varisistor is exceeded, the second auxiliary spark gap is ignited, the arc of which initiates ignition of the first auxiliary spark gap, the arc of which in turn moves towards and ignites the main spark gap. During the arcing time of the spark gap, a controlled discharge of the series capacitor through a resistor (R2) takes place.

Abstract: A protective device for electric motors for protecting electric motors from high operational temperatures, has an element for determining an operational temperature of an electric motor and an element for automatically switching off of the electric motor when a predetermined limiting operational temperature is exceeded. The determining element is formed as electronic element for determining the operational temperature indirectly from an at least another operational parameter of the electric motor. The element for automatically switching off is formed as electronic element for automatically switching off of the electric motor.

Abstract: A multiphase common mode transient suppressor is disclosed which uses a plug choke placed at the utility power service input to the circuit of the present invention. The plug choke contains, for example, three coils corresponding to three power carrying input conductors. Each coil is wound in the same direction, and has the same number of turns. Preferably, a magnetic core is provided around which the coils are wound. At the output of the plug choke are placed three capacitors, in parallel between a grounding conductor and three output conductors. The choke in combination with the capacitors creates a resonant circuit.A control circuit is provided which is connected to the plug choke via a catcher coil. The catcher coil "catches" the flux induced by the transient and dissipates its energy through a resistor, thus dampening the resonant circuit. Current through the resistor is controlled by a semiconductor switch.

Abstract: A low voltage electric power monitoring and circuit breaker system includes two processors. The first processor activates the circuit breaker when an overcurrent condition is detected and the second processor monitors the current sensed by the first processor and activates the circuit breaker for overcurrent conditions which should have caused the first processor to activate the breaker. If a current of this magnitude is detected, the second processor activates the circuit breaker as a backup protection for the first circuit breaker.

Abstract: Fault gas seals to prevent the ejection of a surge arrester from a loadbreak bushing due to the generation of such gas in response to the failure of arrester devices in such surge arrester. A metal O-ring support is bonded to the conductive insert of the arrester housing or added as a retrofit to such housing. Annular grooves in the loadbreak probe are fitted with O-rings which are compressed against the support to provide a gas-tight passage along the probe surface. An additional annular groove can be used to receive a fastener to hold the retrofit in position.

Abstract: Apparatus for remotely controlling electrical equipment includes a ground fault interrupter circuit having a selectively operable circuit breaker for connecting and disconnecting power to the electrical equipment, a transmitter for generating amplitude modulated electromagnetic radiation when it is desired to operate the circuit breaker, and a receiver responsive to the electromagnetic radiation for selectively operating the circuit breaker.

Abstract: An apparatus for protecting an electrical power system supplying electrical power to an electrical load comprises a transformer for sensing an operating condition of the electrical power system and for producing an analog signal representative of the operating condition, and a microcomputer for periodically sampling the analog signal and for converting the analog signal into a series of digital signals. The microcomputer includes circuitry for deriving a digital value representative of a square root of the series of digital signals and circuitry for processing the digital value over time to determine a processed value which is a function of both the sensed operating condition and time. A circuit breaker is responsive to the microcomputer for disconnecting the power system from the load in the event that the processed value is not within preset limits.

Abstract: An electrical connector with the function of instantaneous breaking of a current in response to detection of a leak. The connector comprises: a current supply cord for connecting a load to a source; a pair of plug blades connected electrically with the current supply cord and projected out of a connector body; a sensor mounted in the connector body for detecting a current leak; a breaker device for breaking the connection between the plug blades and the current supply cord in response to a detection by the leak detection sensor.

Abstract: The overload protection circuit 12 comprises a resistor bridge 20 with a low impedance sensing resistor r and high impedance resistors R1 to R4 which generates voltages Va and Vb at the inputs 32 and 34 of a comparator 22. Voltage Vb depend upon the value of the load current so that the comparator provides at its output 36 a control signal for opening the switching device 24 comprising a field effect transistor when the load current exceeds a maximum value. Resistor R5 reinforces the effect of the control signal. This circuit can be used in a system which comprises a central power supply unit 8 which powers a plurality of devices such as 4. The status of the circuit 12 is reported to the system 8 though line 14 and circuit 12 comprises a control circuit 26 which is responsive to set and reset control signals on lines 14 and 18 from the unit 8 to close or open the switch 26.

Abstract: The invention relates to a protective circuit for the protection of the user from overvoltage and overcurrent, in particular for telecommunication installations. Prior art protective circuits comprise a fuse connected into the line connection, and a surge arrester with a heat-sensitive protection device, forming a cross path between the current path of the line connection and the earth conductor, the heat-sensitive protection device disconnecting the cross path in case of excessive power, and connecting it to the earth conductor.In the protective circuit according to the invention, a response of the heat-sensitive protection device (5, 6) will cause disconnection of the cross path of the surge arrester (1, 2) and closing of a short-circuit cross path (7, 8) behind the fuse (3, 4) between the line connection (a, a'; b, b') and the earth conductor (E). The protective circuit can be accommodated in a miniature plug for application in telecommunication installations.

Abstract: This lightning arrester includes (i) a tubular housing comprising a plurality of tubular sections disposed in telescoping aligned relationship to define an internal chamber and (ii) a stack of arrester elements located within this chamber. Locking means between adjacent telescoping sections holds the sections together in aligned relationship.Each locking means between adjacent sections comprises radially-projecting lugs on a telescoping portion of one of the sections and generally L-shaped slots in a telescoping portion of the other of the sections. The lugs fit into the slots and are displaced into locking portions of the slots by twisting motion of one of the adjacent sections relative to the other.In one embodiment, the housing sections are molded components of polymeric material and the lugs are also of polymeric material and are integral portions of the tubular housing on which the lugs are located.

Abstract: A method for the overload protection of devices which cannot endure continuous running on account of heat loss, to avoid a complex, cost-intensive direct coupling of the device to be protected to a temperature measuring element. The inside temperature within the housing of the device is merely measured and, on the basis of device-specific characteristics stored in an evaluation circuit, a permissible operating period assigned to the inside temperature is calculated. The permissible operating period is then used as a basis for the preset operating period cycle time.

Abstract: The ejecting electrical outlet has magnets positioned within the electrical receptacle. Springs are positioned between the magnets and are compressed when the prongs of a plug are entered into the outlet. The strength of a magnetic field generated by an overload electric current is sufficient to defeat the attractive forces between the magnet and to permit decompression of the spring and ejection of the plug from the electrical outlet.

Abstract: A circuit for protecting a CMOS chip against damage from electrostatic discharges (ESD) has four SCRs connected between the line to be protected and the two power supply terminals, V.sub.DD and V.sub.SS. The SCRs are poled to conduct ESD current of either polarity to each power supply terminal. The bipolar transistors for the SCRs and the associated components are arranged in the chip in an advantageous way that reduces the input/output parasitic capacitance and improves the protection capability of this proposed circuit with a low ESD trigger-on voltage.

Abstract: Circuitry is described for isolating a section of a loop circuit (L) from a bi-directional supply unit (20) in the event of a short circuit in the section. One or more circuit elements (21), such as fire detectors, are connected in respective portions of the loop circuit and between respective pairs of bi-directional isolators (1,2,3,4). Each isolator includes switching means (TR1,TR3) providing low and high impedance paths for respectively supplying current to said circuit elements and isolating said circuit elements from the supply unit (20). Each isolator also includes sensing means (TR2, D1, DS7) for sensing a short circuit in any one of the circuit elements (21) whereby the sensing means causes a change in state of the switching means from the low to the high impedance path thereby isolating the circuit elements in the respective section of the loop from the supply unit.