Abstract: An electrical distribution device with preventive checking of the state of the load, particularly for civil and industrial users, having a plurality of electrical tapping outlets which are mutually connected by a single-phase/multiple-phase electrical distribution line and at least one electrical connector for data transmission which is connected to elements for controlling the device. Each outlet is provided with elements for detecting plugs within the respective receptacles; these elements indicate the presence or absence of the plugs to elements for connecting the outlet to the electrical distribution line; each outlet is also provided with elements for detecting phase/neutral polarity and elements for detecting the state of the load. The connecting elements selectively close normally-open coupling elements between the electrical distribution line.

Abstract: In order to obtain an improved operating behavior in the event of short circuits on a high-voltage line having a phase shifter, the phase shifter is used as a current limiter in the event of a fault. A fault signal, which results in an increase in an opposing voltage at an additional transformer of the phase shifter, is produced for this purpose, as a function of a fault current.

Abstract: A single circuit-breaker is provided in the phase conductor, and the bridging circuit is provided on the load side of the single circuit-breaker, and a magnetically driven switching contact closes a bridging current branch leading to the neutral conductor. The bridging circuit conducts a part of the short-circuit current past the magnetic drive and/or the switching contact. A resistor whose resistance value amounts to between 25 and 50% of the value of the smallest load-circuit impedance (L.sub.2, R.sub.2) to be expected, may be provided in the bridging current branch. In such an arrangement, the bridging circuit and the circuit-breaker can form one unit.

Abstract: An electrical apparatus (100) line actuator (102), such as a voltage regulator or circuit breaker, has resident therein a personality module, electronically reconfigurable memory device (126) which stores actuator operational information, such as specifications (132), historical and maintenance information. An apparatus controller (106) communicates with the personality module (126) and can change the operational information stored therein. If either or both of the controller (106) and actuator (102) is replaced at a site, the controller (106) of the replacement apparatus configuration (100) can read the operational information stored in the personality module (126) and adapt its operational interaction with the actuator (102) in conformance with the information.

Abstract: A power distribution circuit is provided that isolates both power source and load faults. In one embodiment, the power distribution circuit includes two power MOSFETs connected with the channels of the power MOSFETs in series and having their gates electrically connected together. The body diode of one power MOSFET is aligned with the opposite polarity with respect to polarity of the body diode of the second power MOSFET. The power MOSFETs are adapted to be coupled between a first power source and a load. The power distribution circuit also includes a first sensor that detects when the power MOSFETs conduct too much current and switches the power MOSFETs off by discharging the gate voltage of both power MOSFETs during such overcurrent conditions. Accordingly, when both power MOSFETs are switched off, the opposing polarity of the body diodes in the power MOSFETs ensures that one of the body diodes will be reversed biased in case of a short circuit failure in either the load or the power source.

Abstract: A broadband communications network having an uninterruptible power supply. The power supply has one input connected to AC line voltage and another input connected to a gas powered electrical generator. The power supply contains an uninterruptible power supply module having a controlled ferroresonant transformer and a battery. The power supply also contains a bypass module having a controlled ferroresonant transformer. Switches are provided to allow either of the inputs to be connected to either the UPS module or the bypass module for the generation of power signals for supplying power to the broadband communications network.

Abstract: The present invention relates to a line fault monitor for detecting a short circuit in a terminal-side loop line and disconnecting the short-circuit portion from a power supply, so that the position of the short circuit can easily be specified. The line fault monitor includes at least one of a mid-point line monitoring device and a beginning/end line monitoring device. The mid-point line monitoring device has a first fault indicator lamp for indicating a fault in a line connected to one terminal, and a second fault indicator lamp for indicating a fault in a line connected to the other terminal. The beginning/end line monitoring device in the side of a receiver has a first fault indicator lamp for indicating a fault in a line connected to a beginning terminal, a second fault indicator lamp for indicating a fault in a line connected to an end terminal, and a representative fault indicator lamp for representatively indicating a fault in any one of the lines connected to the beginning and the end terminals.

Abstract: An apparatus for enabling pilot wire relays to communicate across voice-grade, non-metallic communication channels converts sinusoid signals representative of phase currents at a location in an electric power distribution system to audio band signals representative of the phase of the current signal at that location. These audio band signals are transmitted over a voice-grade non-metallic communication channel to a remote interface module where they are converted to square waves which are compared against square waves representative of the currents in the electrical power distribution system at that location.

Abstract: An electrical control system for sensing instantaneous total electrical power consumption being delivered into a facility and for interrupting selected electrical current consuming loads within the facility when the total incoming current consumption exceeds one or more preselected maximum level for a continuous first preselected time period. The system utilizes existing power transmission lines within the facility to sequentially transmit at least two pulsed digital shut down signals on each of at least two phases or legs of transmission lines within the facility to one or more remote shut down units at the end of the continuous time period. Each remote unit then interrupts electrical power to at least one electrical load within the building for a second preselected time period, after which power is restored to the electrical load until the total current consumption again exceeds one of the preselected maximum load levels continuously for the first time period.

Abstract: A power stoppage minimizing system for a distribution line and a method of using a distribution line minimize a power stoppage section and a power stoppage time when a short circuit occurs in the distribution line, and employs a first and a second distribution line each connected through a circuit breaker to a corresponding bus and each having switches in position thereon; a normally open tie point switchgear provided between adjacent ends of the first and second distribution lines; a protective relay for opening, when a short circuit has occurred, the circuit breaker a fixed time after the occurrence of the short circuit on the first distribution line; a first unit for opening a switch on the side of a power source and nearest a point where the short circuit has occurred; a second unit for opening, after the switch is opened by the first unit, a switch on the side of a load nearest the switch opened by the first unit; and a third unit for closing the tie point switchgear after the opening of the switch by th

Abstract: A fast and reliable method for determining power system transient stability is presented for on-line power system dynamic security assessment. This method is based on the direct (Lyapunov theory) approach controlling the unstable equilibrium point (UEP). Lyapunov technique, however, cannot be used on-line, since calculating the controlling UEP is a computational intensive problem, even for a computer. The invention comprises determining the controlling UEP of a reduced system and relates the controlling UEP of the reduced system to the controlling UEP of the original system. The invention has a sound theoretical basis. The invention eliminates the difficulty of having to find the controlling UEP. The method of the invention determines the constant energy region that surrounds the controlling UEP of the original system. This region is used to approximate the stability region boundary intersection point that a particular fault trajectory will traverse.

Abstract: The relay includes an input module capable of receiving 70 volt and 5 amp signals, respectively, from conventional instrument transformers, which are responsive to power line signals at their primaries. Output signals from the input module have specified, standardized levels suitable for electronic processing circuits, i.e. 1.4 volts and 0.1 volt. The output signals from the input module are applied through an accessible connector to a separate processing module which uses those signals in a conventional manner to determine possible faults on the power line. Low-level testing is accomplished by testing the outputs of the input module and by applying test signals simulating the standardized outputs of the input module to the processing module.

Abstract: In a power receiving system, a network transformer, a protector breaker and a current detector are connected between the load side of each of a plurality of network lines and a network bus, a breaker is connected to the primary side of the network transformer, the current detector being operative to detect an accident current on the secondary side of the network transformer, and relays or an operation controller is provided which is responsive to the detection signal to open the breaker and protector breaker to switch off accident currents on the primary and secondary sides of the network transformer, whereby the protective range is so expanded as to cover a line section between the network transformer and the protector breaker and the scale of the overall power receiving system is reduced.

Abstract: A NO-BLO-FUSE comprising a current sensing device is used to generate a voltage drop proportional to the current flowing through the device. When the voltage drop reaches a predetermined level, resulting from an over-current condition, it trips a control means that opens a solid state switch in the line. After a defined delay interval the circuit will automatically reset to close the solid state switch. If the over-current condition still exists, the control means will again open the solid state switch. This cycle is repeated at the delay interval until the over-current condition has subsided. Circuits are also disclosed which provide over-voltage protection, through detectors which trigger the control means when an over-voltage condition is detected. The application of the invention to lightning or surge protection is also disclosed, for single line and multi-line environments.

Abstract: A micro computer based power line protection, monitoring and management system that manages one or more source(s) and one or more user(s) of the power. Further disclosed are many means of rendering the surge protection operative in many different modes, and conditions, means of providing primary protection and secondary protection in a safe way such that the system integrity is maintained in that various situation/conditions of power surges, transients and crosses, further coupled with a power management system that allows safe switching between surges and manages different loads and provided by its predetermined parameters and conditions. External communication means additionally provide the means of controlling and monitoring the sources and the loads. Various control means and isolation means separate the primary from the secondary protector providing fail safe protection under varying power conditions such as power crosses, surges and transients.

Abstract: A safety disconnect system for an installation comprising machines which are designed to interact, has a machine disconnect level in which a dedicated disconnect circuit is allocated to each machine, an area disconnect level, in which disconnect areas which comprise groups of associated machines can be disconnected, and a system disconnect level which is allocated to all the machines of the installation. The disconnect circuits in each case have an electrically operable switching element which is connected via safety circuits to a main box for the central control of the safety disconnect system and, through this box, to a power supply. The safety circuits have operable tripping elements at the area disconnect level and at the system disconnect level, are constructed as latching circuits and are passed through the main box in which they can optionally be linked to one another by means of a switching matrix such that groups of associated machines are disconnected if one of the tripping elements is operated.

Abstract: An arrangement to coordinate protective devices is provided by defining operation of the instantaneous characteristic portion of an upstream protective device to coordinate with a downstream current-limiting fuse based on the peak let-through current of the downstream current-limiting device, with instantaneous operation being set to occur only above the peak let-through current of the downstream current-limiting fuse. Accordingly, for fault currents which are seen by both the instantaneous device and the current-limiting device and that are within the ratings of the current-limiting device, the upstream device will not respond and the downstream current-limiting fuse will interrupt the fault, as intended.

Abstract: An isolation circuit, which draws essentially zero current in a normal or stand-by state, uses a normally closed relay in combination with a storage element. A capacitor can be used as the storage element to energize the relay, using previously stored energy, in the event that a communication line to which the isolator is coupled exhibits a short circuit or low voltage condition. In this instance, the prestored energy on the capacitor activates the relay for a predetermined period of time, thereby open circuiting the communication line. When voltage is reapplied to one side of the isolator circuit, the relay is continuously energized and maintained in its open circuit condition until the low voltage or short circuit has been remedied.

Abstract: A nonvolatile fail-safe system providing protection from bus fault propagation for a multi-channel electric power generating system includes a controller which provides excitation control and protection for a first generator unit, position control for its generator control breaker (GCB) and position control for a bus tie breaker (BTB); protection logic which generates a trip signal for the BTB when a bus fault is detected isolating the load distribution bus from the tie bus, and thereafter generating an excitation isolation control signal and a GCB trip signal isolating the load distribution bus from the generator unit upon sustained presence of the bus fault. A latching generator control relay is electrically coupled in series with the excitation control and is responsive to the excitation isolation control signal for de-energizing the generator by isolating the excitation control.

Abstract: Control and self-monitoring system for an electrical apparatus comprising three poles, each including a closing coil and an opening coil, an opened auxiliary contact, and a closed auxiliary contact, wherein each of the poles is provided with a microprocessor receiving, in particular, information from the opened auxiliary contacts and controlling two static relays in series respectively with the circuit of the opening coil and in the circuit of the closing coil, the microprocessors being subscribers to a local bus comprising a serial bus under the control of a management member and connected to a processor station receiving the signals collected by the microprocessors and the signals issued by the protection devices or by the operator.

Abstract: A system for protecting a remote power supply for supplying power to an optical subscriber network, via a pair of power supply lines, from a remote power supply apparatus, being provided with power supply branch apparatuses inserted into the power supply lines in correspondence with each power receiving circuit respectively mounted in subscriber transmission nodes. Each of the power supply branch apparatuses comprises relay contacts inserted into its own power supply branch lines connected between the power supply lines and its own power receiving circuit, and a relay energized by an overcurrent detector or first and second communication units to change over the relay contacts. The relay contacts are opened and closed subscriber by subscriber sequentially to detect a faulty portion, and thereafter, the power is fed again selectively to the subscribers which have not experienced the fault.

Abstract: A main controller installed in a distribution substation of an electric power system sends a request signal to each of section controllers installed in individual section switches upon detecting a distribution line fault. Each of the section controllers performs fault detection individually. Each section controller judges whether its associated section switch is dividing the distribution line between faulty and normal line sections on the basis of fault detect signals from the other section controllers. If it is judged that its associated section switch is dividing the distribution line between faulty and normal line sections, that section controller opens its associated section switch.

Abstract: A feeding system is provided for supplying a current to repeaters on a communication cable including a feed line for conducting a current to the repeaters. The feeding system includes a plurality of branching units provided on the communication cable and terminal stations each being connected through at least one of the repeaters to one of the branching units, and each of the terminal stations feeding a current through the feed line to the repeaters. In addition each of the plurality of branching units includes at least one switching circuit for switching to connect the at least one of the repeaters to the communication cable or to the ground, depending on the amount of current conducting through the feed line in the communication cable. Further, the current thresholds of the switching circuits in the plurality of branching units are preferably different from each other.

Abstract: In a protective relay (10), which contains a microprocessor (30), for monitoring a power transmission line, an output enable decoder (72) and a one-shot timer (74) produce a very short (5 microsecond) signal in response to an address signal from the microprocessor. The output from the timer is applied as one input to AND gate (70). A conventional address decoder, responsive to an address signal identifying a particular output port from the microprocessor, provides another output to AND gate (70). AND gate (70) produces a latch control signal when the two signals are coincident in time. The latch control signal enables the particular output port to receive instructions from a data bus (60).

Abstract: A breaker failure relay circuit is responsive to either a trip signal from a protective relay or a manual trip signal, as well as the current through a circuit breaker protecting a transmission line. The trip signal is applied to an edge triggered timer (28) having selected pickup and dropout times, and is also applied as one input to one OR gate (24). The circuit breaker current is applied to an overcurrent element (34), the output of which is applied to a reset input of the edge triggered timer (28) to reset and disable the timer and also as one input to another OR gate (30). The other input to OR gate (30) is the output of the edge triggered timer (28). The outputs of OR gates (24, 30) are applied to an AND gate (26), the output of which is applied to a second timer (32) and as another input to the one OR gate (24). The output of the timer (32), if and when it occurs, is used as a trip signal for a backup circuit breaker.

Abstract: A microprocessor based tie relay controls a tie circuit breaker between a main bus and a transfer bus to which any one of a number of feeder lines may be connected through a disconnect switch when the feeder circuit breaker associated with that feeder line is out of service. Settings for the protection characteristics of each of the feeder relays controlling the feeder circuit breakers are stored in non-volatile memory together with a default protection characteristic suitable for protecting any of the feeder lines. The appropriate protection characteristic for the feeder line connected to the transfer bus is selected for use by the tie relay in controlling the tie circuit breaker. This selection may be made manually by an operator, or preferably automatically by the microprocessor of the tie relay which monitors the states of the feeder circuit breakers and of the disconnect switches and selects the settings associated with the feeder line whose feeder circuit breaker is open and disconnect switch is closed.

Abstract: An alarm system in which a pair of transmission lines are disposed in a loop to define two channels of transmission from a controller to a group of interconnected detectors, the improvement comprising a spaced group of line fault isolators interleaved with respective sub-groups of detectors and connected across the lines for sensing a short circuit on the transmission lines so as to isolate the short circuit condition; the isolators including an arrangement for switching, in response to a signal transmitted from the controller, those isolators which are physically located adjacent to the short circuit without interfering with the operation of other detectors in the loop.

Abstract: In accordance with illustrative embodiments of the present invention as disclosed herein, a safety switch for preventing accidental firing of an explosive well tool includes a tubular metal body connected between the cable head and the well tool, a conductor wire extending through such body for carrying current from the cable to the well tool, and a contact plug mounted in a slide opening in the body and arranged to be selectively advanced into shorting contact with the conductor wire.

Abstract: A remote power-feeding and protection system for equipment connected by two transformers to a four-wire transmission link.The remote power-feeding and protection system and the remote power-feeding extractor protection device are intended for equipment connected by two transformers to a transmission link with two pairs of wires ensuring remote power-feeding of the fed equipment.Each transformer is connected to the two wires of one pair by two identical windings serially-connected between these two wires through a capacitor. The two pairs of wires constitute a phantom feed circuit, the two wires of a given pair being connected to the same terminal of a D.C. generator. The extraction and protection device comprises two rectifier bridges each separately connected by their inputs to a pair of wires and interconnected by their outputs in order to provide remote power feeding.

Abstract: Discriminating circuits are coupled to receive signals from a protected transmission circuit. Each discriminating circuit also receives from a direction detector signals indicating whether any fault which occurs is forward of, or reverse of, a predetermined point. The discriminating circuit is arranged to produce an output signal to trip a circuit breaker of the protected circuit only if a fault occurs within the protected circuit. In this respect, the discriminating circuit only outputs a trip signal if it receives within the same time period both a signal from the direction detector indicating that the fault is appropriately located, and high frequency signals from the protected circuit. The system thus utilizes the high frequency noise invariably generated when faults arise in transmission circuits.

Abstract: A state signal is formed to indicate a transition to a bypass mode of operation. In forming the signal of each winding system of a corresponding converter transformer on a side of the converter transformer are determined, weighted with weighting factors and summed up. The summation current formed in this manner does not have any null zones in the normal operation of the converter. All weighting factors are different if the phase currents between the converter and the converter transformer are used to produce the summation current. In the case of a converter transformer which is connected to the converter via a delta-connected winding system and in which the winding currents are used, certain differences formed by the weighting factors are not to be the same. A DC Hall converter with an insertion hole is particularly well suited for weighting and combining the currents of each individual winding system.

Abstract: A device (10) for interfacing a line voltage breaker box (14) with a low voltage controller (30). The device (10) includes a housing (12) which shields the electrical component contained therein. A plurality of low voltage connectors (46) are mounted in the housing and electrically connected with a low voltage controller (30). Each of the connectors (46) includes a low voltage actuator (32) which is selectively energized by the controller (30). A plurality of line voltage connectors (56) are mounted in the housing (12) at a location spaced from the low voltage connectors (46). These line voltage connectors (56) electrically connect line voltage to breakers (16) in the breaker box. Each of the connectors (56) include a line voltage switch or contact (54) which is operatively associated with at least one of the actuators such that energization of the actuator causes the switch (54) to close and power to be supplied to said breakers and appliances operatively associated therewith.

Abstract: An electronic circuit for use with an electrical generator having a voltage regulator which responds to raise or lower control signals to change the voltage output of the generator. The electronic circuit has a circuit for sensing the magnitude of the difference between the voltage output of the generator and the voltage of a bus to which the generator is to be connected. The electronic circuit also includes a circuit for generating control pulses, each control pulse having a fixed maximum pulse duration when the magnitude of the difference is greater than a first predetermined value but which decreases with a decreasing magnitude of difference down to a fixed minimum pulse duration at a second and lesser predetermined magnitude of difference when the magnitude sensed is less than the first predetermined value.

Abstract: A method and apparatus for detecting voltage losses in a power distribution line wherein a plurality of voltage sensing devices are used to generate an alarm signal which identifies the phases and locations corresponding to points at which voltage losses are detected.

Abstract: Protective relay for use in an electrical power system having electrical conductors which are energizable with an AC voltage. The protective relay includes a circuit for sensing the AC voltage to produce an AC output that has zero crossings and a time period between zero crossings, a circuit for supplying an electrical signal representing a preselected pickup value of volts-per-Hertz for the relay, and a circuit responsive to the AC output and to the electrical signal for generating an electrical level as a function of both the time period and the pickup value and for producing an output signal for the relay when the AC output exceeds the electrical level. In this way, the output signal is produced when a volts-per-Hertz value of the AC voltage exceeds the preselected pickup value of volts-per-Hertz for the relay. Other protective relay apparatus and methods are also disclosed.

Abstract: In a circuit arrangement for automatic connection of a remote feed current path of a remote feed loop fed from both sides for electrical loads with direct current series feed, a parallel circuit of a first four-terminal network comprising two feed outputs and a second four-terminal network containing a connecting two-terminal network, controllable by current sensors, is provided for the acquisition of a feed output per remote feed current path, this being undertaken by way of diode current branches. The circuit arrangement can advantageously be employed for the remote feed of regenerators and communications transmission links.

Abstract: A power transmission system with current-limiting devices having a plurality of power transmission stations for transmitting power from a power-receiving line to respective loads wherein each current-limiting device includes a series circuit constructed of current-limiting elements and a bypass switch connected in parallel thereto. The terminals at one end of the limiting devices are connected to corresponding buses of the transmission stations while the terminals at the other end are connected to each other.

Abstract: A transmission line protection system arranged such that a leakage current detector is provided at an end of an insulating device such as an insulator connected at one end to a corresponding one of arms of a steel tower and connected at the other end to a transmission line of each phase, thereby detecting an arrester leakage current flowing in the transmission line of each phase, an output signal of the leakage current detector being led to a repeater through an optical fiber cable, an output of the repeater being transferred to a control/supervisory board in a substation through an optical fiber cable. In the control/supervisory board, preferably, a received digital signal which was converted from an analog signal at said leakage current detector is displayed on a cathode ray tube. In such an arrangement, it is possible to smoothly perform supervision of the status of the transmission lines without causing maloperations due to influences from the transmission lines.

Abstract: A microprocessor-based electronic control unit utilizes a random pattern lock and key failure detection scheme to detect failures in the system being controlled or the control unit itself. The microprocessor system is programmed to receive a random data word, to output the same data word, and to perform a variety of tests which result in the generation of a data stream having a particular relationship to the random data word such that the data stream and the random data word bits can be combined to form a predetermined data word that is needed to maintain microprocessor control of the associated electrical system. If the microprocessor fails to generate a data stream which results in the formation of the proper predetermined data word, the control unit output will be locked into a predetermined state.

Abstract: A protective relay for detecting power arcing faults on a low-voltage spot network. The protective relay can monitor the voltage difference between each phase conductor, the voltage difference between each phase conductor and the neutral conductor, or the current on each phase conductor. Using one of these three sets of values, the protective relay first filters the input signal so that only frequencies indicative of a power arcing fault on the low-voltage spot network are analyzed. The signals passed by the filter are amplified, rectified, and averaged and the peak of each signal detected. If the peak has a duration longer than a predetermined value, a fault indication is provided.

Abstract: Differential current static trip circuits interconnected with upstream and downstream current sensing transformers in a protected system provide automatic coordination of the downstream static trip circuit breakers. The differential current transformer associated with the breakers vectorially sense the difference between the upstream breaker currents and the sum of the downstream breaker currents. The output is processed within the trip circuits for I.sup.2 t and fixed time band delays to insure that the downstream breakers clear the fault.

Abstract: A circuit arrangement comprises two feed circuits which are connectible to a load with mutually opposite polarity. The circuit arrangement avoids mechanical contacts in the load circuit, at least with respect to one feed circuit. This is achieved in that switches, provided for the activation at at least one of the feed circuits, are disposed outside of the output circuit and in that a transistor is disposed between such a feed circuit and the load, this transistor being conductive given an activated feed circuit and being inhibited given a deactivated feed circuit. The circuit arrangement can advantageously be employed in remote feed devices of communications transmission device for the purpose of optionally feeding a remote feed section with a remote feed current or with a fault locating voltage.

Abstract: A protective relay for detecting power arcing faults on a three-phase electrical power spot network. A phase-to-phase power arc on a spot network produces harmonics on the phase-to-phase voltages, and the phase currents; a phase-to-ground arc produces harmonics on the phase-to-neutral voltages. The protective relay of the present invention monitors one or more of the three phase-to-phase voltages, the three phase-to-neutral voltages, or the three phase currents and indicates a fault based on the harmonic content of those signals.

Abstract: In a high-voltage switching system, nodes (1, 2, . . . , 8) are connected in the form of a ring via switching points (12, 23, . . . , ) which in each case contain a circuit breaker. In this system, the breaking currents of the circuit breakers are to be limited and thus the breaking capacity of the circuit breakers provided in the system is to be reduced if a short-circuited part (for example node 1) is separated from a faultless part of the system. This is achieved by opening a switching point (for example 45) of the nodes connected in the form of a ring, between the contact feeders of which switching point and the non-available node (for example (1) in each case at least one available node (for example 2, 3, 4, 5, 6, 7, 8) is provided, via which a component short circuit is fed into the ring.

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, D7) 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.

Abstract: A fault detection and clearance system for paralleled electrically similar power transmission lines wherein at each end of the line matched separate directional relays respectively connected to trip associated fault clearance circuit breakers have polarized windings and operate windings. The polarized windings are energized by an alternating current proportional to the summation while the operate windings are energized by an alternating current proportional to the difference (phase considered) of fault currents going into the breakers in both lines at the adjacent end in the event of a fault.

Abstract: In a switching system having n nodes (1,2 . . . 6) which are connected via interruptible current branches (11,12 . . . 16) in the form of a ring, in the case of non-availability of at least one of the nodes or at least one of the switching points provided in the interruptible current branches (for example 11) the nodes which are still available are to be connected in the form of a ring, the structure of which is nearly unaltered in the undisturbed areas of the switching system with respect to the corresponding structure of the ring provided in the undisturbed system. For this purpose, n dual isolating switches (31a, 32a, . . . ) and a circuit breaker (a) are provided which are connected to the nodes (1,2 . . . 6) in such a manner that each node (for example 1) can be connected to any one of the other nodes (for example 2) via one of the n dual isolating switches (for example 31a), the circuit breaker (a) and another one of the n dual isolating switches (for example 32a).

Abstract: A zone selective interlock module is interposed between a pair of upstream and downstream static trip circuit breakers for controlling the short-time and ground fault zone selective interlock functions of the breakers. When a signal is received from a downstream static trip breaker, the module transmits a low-level interlock signal to a static trip breaker upstream. The interlock signal, in turn, activates the programmer circuit of the upstream breaker causing a shift in the upstream programmer time delay characteristics. The module also provides an energy storage feature to ensure the integrity of the interlock function in the event that the control power is lost upon the occurrence of a fault.

Abstract: A switching device that relates to the arrangement of a switching network for use within an electrical power distribution system. There is an improved security of power delivery to various loads while at the same time enabling a reduction in the number of required circuit breakers and related gear. This network also presents additional options in design and operating modes, when applied to distribution systems. These options result in a reduction in the total installed capacity of the sources together with reduced continuous current and fault current ratings of conductors and interconnected apparatus. The invention provides a switching network has six conducting branches, each branch containing at least one switching means such as a circuit breaker. The branches are connected at their ends to form four 3-sided rings, each branch forming a side of and being shared by two of the rings.

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.