Abstract: An electrical power supply system includes an electrical power source system connected to a bus bar and a plurality of electric power transmission systems each connected via circuit breakers to the bus bar. The supply system has overvoltage suppression equipments each installed between the transmission system and the ground. The overvoltage suppression equipment includes a switching device and an impedance connected to the switching device. The switching device in a sound transmission system is closed when the circuit breaker operates in other faulty transmission system, thereby an overvoltage being occurred on the sound system is effectively suppressed.

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 embodiment of the present invention is a ballast for a high intensity discharge lamp that includes a non-automatically resetting thermal protector thermally coupled to a coil wound on a core and insulation between the coil and the core. Only one cycle is allowed into what may be a range of temperatures capable of destroying the insulation within the ballast.

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 junction box for the protection of electronic devices and communication lines from lightning surges, overcurrent and overvoltage. The box includes sockets for connection to the devices and liens along with a plurality of combinations of surge absorbing elements and low melting point metal wires for the protection feature.

Abstract: A surge protection device to protect telecommunication equipment coupled to telephone lines is shown having in a first embodiment three cells with each cell having a semiconductor element with a reverse breakdown PN junction mounted on a heat sink. The device includes a lead frame having a first pair of leads formed with a platform raised out of the plane of the remainder of the lead frame to provide suitable clearance relative to the semiconducting elements and each platform has a finger extending downwardly into engagement with a top electrode of a respective semiconducting element and is soldered thereto. A second lead lies in the plane of the lead frame and is soldered to a first heat sink plate mounting two semiconducting elements and another finger extending from one of the platforms is soldered to a second heat sink plate mounting the third semiconducting element. The heat sinks, semiconducting elements and portions of the leads are encapsulated in thermally conductive, electrically insulative epoxy.

Abstract: A transient voltage surge suppressor comprises a first series circuit formed of a normally-off voltage surge-responsive gas discharge tube and a first voltage clamping device connected across input terminals to which a line voltage is applied. It also includes a second series circuit formed of a first electrical energy absorbing impedance element and a second voltage clamping device connected across the first voltage clamping element, thereby forming a voltage-clamping, voltage divider circuit which clamps the voltage across the first voltage clamping element at a voltage level reduced in comparison with that obtained by the first series circuit alone. When the gas discharge tube turns on, it places both voltage clamping devices in the circuit simultaneously, so that the let-through voltage appearing across output terminals can be reduced to the voltage clamped by the voltage-clamping, voltage divider circuit.

Abstract: A gravure printing press with an electrostatic assist unit having a fault detection circuit and crowbar circuit in which the crowbar circuit has a transformer with a primary winding and a plurality of secondary windings. Each of the secondary windings has a field-effect transistor which is turned on in response to the detection of a fault condition whereby the voltage applied to the press is substantially reduced to zero and any electrostatic charge is substantially removed. A capacitor is coupled in parallel with the gate and source terminals of each field-effect transistor to lengthen the on-time of the transistors.

Abstract: There is provided a circuit that protects the electronic tripping circuitry of a circuit breaker system from external transient high voltages and prolonged high voltage faults. The circuit preferably includes a transzorb that conducts in response to receiving a voltage signal having a magnitude greater than the breakdown voltage of the transzorb. This transzorb clamps the output voltage to its breakdown voltage. The circuit also includes a fuse that is designed to blow in response to a prolonged high voltage fault.

Abstract: In an electronic endoscope apparatus, an overvoltage is produced by discharging electrostatic energy induced on an electronic scope made of a synthetic resin. The electronic scope used for the electronic endoscope apparatus comprises: a solid-state image sensor for producing an image signal of a biological body under medical examination, the image signal being derived from a signal line of the image sensor; and, an overvoltage protecting circuit for protecting the image sensor against an overvoltage caused by at least one of electrostatic energy induced on the electronic scope and interruption of source power supplied from the electronic endoscope apparatus to the image sensor, by maintaining at least said signal line at the same potential.

Abstract: A semiconductor integrated circuit includes a semiconductor chip having a predetermined circuit device and a PN junction diode group formed on the surface thereof. The PN junction diode group is supplied with a constant current in the forward direction, whereby the potential difference between the terminals thereof changes according to the surface temperature of the semiconductor chip. A potential difference generating circuit generates a fixed potential difference corresponding to a predetermined limit temperature of the chip surface, whereby the potential difference between the terminals of the PN junction diode group is compared with the fixed potential difference. As a result, when the determination in made that the temperature of the semiconductor chip surface reaches the limit temperature, the operation of the circuit device is temporarily or completely halted.

Abstract: A protection arrangement for coupling a two-wire line to a SLIC includes surge protecting triacs between each wire and ground, and normally closed contacts coupling the wires to the SLIC. The triacs are triggered via varistors coupled to the wires on the SLIC side of the contacts, which are opened in response to over-voltages on the line, as detected via a diode bridge and threshold circuit. The triacs are thereby not triggered during over-voltage conditions so that their power dissipation is reduced during such faults, whereas they respond rapidly to surge conditions which accordingly need not be handled by the contacts.

Abstract: An protection barrier provides voltage and current necessarily conveyed to hazardous, such as explosive, areas. The system includes a current sensing circuit which triggers a silicon control rectifier based crowbar circuit in the event over current is detected. This triggering, in turn, trips a relay severing the current path entirely. A reverse polarity circuit provides for immediate clamping of improperly bias connections in a similar crowbar arrangement, and also provides for tripping of the circuit breaker. Thermistors are also provided in current series in the event the circuit breaker fails to trip, or is forcibly bypassed. The circuit breaker additional provides a visual indicator when it is in the tripped position. The intrinsic barrier system is suitable to serving as a first stage protection to zener barrier modules as utilized in the prior art.

Abstract: A synchronized ballast for a discharge lamp having an increased dimming range. The ballast includes a combined overvoltage and reverse voltage protection device for an electronic circuit operable from a direct current supply is disclosed.

Abstract: An apparatus is provided for controlling an electric motor that is doing some sort of work, whereby the apparatus automatically senses the presence of a work overload. Once the work overload is sensed, the apparatus automatically reverses the direction of rotation of the motor to eliminate the work overload. The reversed rotation is limited to either a predetermined period of time or to a predetermined number of reverse rotations. Once the predetermined limit of reverse rotation is reached, the apparatus automatically resumes normal rotation of the motor.

Abstract: A protected digital output circuit coupled to a programmable controller, for controlling a load supplied through alternating-current (ac) power lines, including a fuse and a single controlled output switch connected in series with the load, and a pair of series-connected crowbar switches connected together across the ac power lines. The crowbar switches can be commanded closed together in the event that the output switch is commanded open but fails to open, thereby shorting the ac power lines and disconnecting the load by blowing the fuse. In routine diagnostic testing, the crowbar switches can be commanded closed separately to check their operation without blowing the fuse. A current detection circuit is used to check for current in the closed crowbar switch. A current sensor is also used to detect current through the output switch, when commanded closed for switching the load on, or for diagnostic turn-on testing when the load is disconnected.

Abstract: Protective circuits for preventing fires due to arc short circuits (as opposed to dead short circuits), are described. Current flow in excess of that existing during normal transient overloads is indicative of an arc short circuit. Protection is provided by triacs which are triggered by circuit current flow in excess of that existing during normal transient overloads. When triggered, the triacs, in series with the fuse or circuit breaker, are placed directly across the power source and thus actuated substantially instantaneously to interrupt current flow to the load circuit. By thus interrupting current flow the hazard of a fire is obviated. Means are also provided for giving a visual indicium that the protective circuit has been actuated by triggering of the triacs. Additional means are provided for triggering the triacs in response to an overheated main electrical service connection.

Abstract: A fault current protection arrangement for a power converter circuit utilizes gate turn-off thyristors as electronic switching devices. A gate turn-off thyristor is connected between relatively positive and negative voltage buses with a circuit interruption device connected in electrical series arrangement with a cathode terminal of the thyristor. A gate driver circuit is connected for providing control signals to the gate terminal of the thyristor for controlling its on and off states during normal operation. Upon detection of the fault current condition, the gate driver circuit is inhibited and the interruption device open-circuits the cathode terminal of the thyristor to divert current in the thyristor into the gate terminal. The resulting anode-to-gate current results in rapid turn-off of the thyristor.

Abstract: A power line filter suppresses or dissipates and clamps short rise time high voltage transients carried by power transmission lines and provides continuous protection against continuous type induced noise. The power line filter includes one or more modules connected to either direct current or alternating current power lines to protect sensitive electrical equipment from the transients and continuous noise. The module used with a direct current power line includes a continuous suppressor connected between a source and load, and a selenium surge suppressor and a metal oxide varistor connected in parallel across the source. The module used with an alternating current power line includes a continuous suppressor connected between the source and the load, and a selenium surge suppressor and a gas tube connected in parallel across the source. The module used with the alternating current power line can also include a metal oxide varistor also connected in parallel across the source.

Abstract: A fault current diverter for use with high voltage electrical equipment is operative to divert fault current to ground by establishing a non-arcing low impedance current path to ground. The diverter includes a switching device having a moving contact which, in response to the triggering of a chemical propellant charge, is rapidly driven so as to pierce solid insulation and make contact with a high voltage conductor or terminal thereby to establish the non-arcing low impedance path.

Abstract: A shunting element includes first and second electrical terminals for shunting an electrical component, a semiconductor component, and at least two electrically conducting parts partly formed in springs being electrically conductingly connected between the semiconductor component and one of the electrical terminals, the terminals being connected to each other with a low resistance through the electrically conducting parts when a current flows which raises the temperature in the semiconductor component to a given value.

Abstract: A system having a bus protected against overvoltage by a plurality of series connected zinc oxide varistors in a column, uses temperature sensors to protect the varistors from damage. First temperature sensors detect that a safety tripping temperature has been reached and lower the bus voltage. Second temperature sensors detect a thermal runaway temperature has been reached and disconnect the bus. Normal operation is restored when the detected temperature falls below the safety tripping temperature. To protect against very rapidly increasing overvoltages, the current flow is monitored and when it exceeds a threshold a signal representing current is integrated. When the integrated value reaches a first preset level the voltage on the bus is reduced and when it reaches a second preset level the bus is disconnected to permit the varistors to cool.

Abstract: A protection apparatus for a transistor inverter including a detecting circuit connected to a logic circuit detecting the base current and the collector-emitter voltage of a pair of transistors in the inverter to be protected. A logic circuit performs a logical operation on a binary signal based on the base current of one of the transistors and the collector-emitter voltage of the other of the transistors in the pair. When a short circuit in either one of the transistors is detected, the logic circuit operates a protective thyristor which causes a short circuit current to flow through fuses connected to the transistors, thereby electrically cutting off the transistors by the blow out of the fuses.

Abstract: A power line transient surge suppressor circuit features a nonlinear surge-bypassing network connected to bypass line surges around electrical loads connected to circuit output terminals. A fuse is inserted in series with the network, and blows in the event of short-circuit failure of a regulator device in the network. A thermal cut-out preferably of the irreversibly actuated type is inserted in series with the suppressor circuit input. A current-limiting heater resistor connected in parallel with the fuse supplies heat to trip the cut-out after the fuse blows, thereby permanently terminating power output to the loads. A similar suppression network is provided for the earth lead in three-wire systems.

Abstract: Circuitry for use in a power supply of the type which includes a power switching means and uses a waveform of predetermined shape to control the power switching means such as in a first mode the supply regulates its output voltage and in a second mode controls the current in the power switching means. The circuitry attempts to turn the supply off in response to an overvoltage condition at its output and failing that provides a short circuit path so that current sufficient to cause the fuse in the output to open will flow therethrough.

Abstract: A safety switch for a glass door, which is used for refrigerating and deep freeze chambers and comprises two or more glass panes of hardened glass, of which the front pane (21) remote from the refrigerating and deep freeze chamber is heated by an electrically conductive layer attached on the inner surface of the pane, which layer is connected to an upper and, respectively, lower collecting conductor, and the rear pane (22) facing to the refrigerating and deep freeze chamber is provided with at least one conductor attached on the pane. The conductors are connected to a current scanning device (20), which is capable to scan whether current flows through said collecting conductors and the conductor of the rear pane, and which is capable to break the connection between the conductors of the two panes (21,22) and a voltage source (46) in the event that current does not flow in the collecting conductors and/or in the conductor of the rear pane.

Abstract: A self-contained fused unit for the protection of electrical appliances against damage caused by abnormal power surges is disclosed. Fuses are selected so that the proper amperage required to operate any appliance can be delivered through the power surge isolator while full protection of the appliance against abnormal power surges is provided. Varistors connected between terminals of the device augment the protective action of fuses in the event that certain kinds of power surges are encountered which are so fast that fuses may not blow in time to protect the appliance. In such cases, the instantly decreased resistance in the varistors assures grounding of the excessive current without damage to the appliance occurring.

Abstract: The protective circuit against overpoling and overloading of an electronic consumer includes a combination of a zener diode connected parallel to the consumer and a parallel connection of a fuse and a conventional diode connected in series with one power supply terminal. Preferably an additional fuse is connected in series between the power supply and the first-mentioned fuse. In the case of a polarity reversal, a fuse burns out, but after restoring normal operational conditions the protective circuit permits operation of the consumer.

Abstract: A foldback power supply (12) is used in an automatic testing device for application of power to a device under test (17). Connection to the device under test is made by means of relay contacts (32, 34, 36, and 38). Arcing and unacceptable transients are avoided by means of a current sink (40) in parallel with the power supply (20). The current sink is operated to draw more than the rated current of the power supply so that the power-supply voltage drops to an acceptable level and the stored energy is simultaneously dissipated. The relay contacts (32, 34, 36, and 38) can then be opened or closed without unacceptably large transients and without the time delays that might otherwise be encountered in waiting for energy dissipation of the energy in the energy-storage elements of the power supply (12) and the device under test (17).

Abstract: Apparatus for preventing a fire in electrical equipment when a relatively constant overvoltage condition appears on an input line comprises a meltable fuse in the line and a surge arrestor connected between the equipment side of the fuse and ground. The surge arrestor is physically located adjacent the fuse for melting the latter and open circuiting the line when the overvoltage condition is present for greater than a net prescribed time interval. In a preferred embodiment, the line adjacent the electrical equipment is a printed conductive line on one side of a circuit board, with the fuse comprising a gap in the printed line that is bridged with a bead of solder. The surge arrester is located under the solder bridge, with one of its leads extending through the board and connected to the printed conductor within the solder bridge.

Abstract: The apparatus includes three electrodes housed in a single enclosure which is filled with a gas. A first one of the electrodes is connected to the junction of a load and a fuse. A second one of the electrodes is connected to an intermediate point of the load, which intermediate point separates the load into two normally equal impedance segments. A third one of the electrodes is connected to the other end of the load. When either of the impedances of the two segments of the load changes sufficiently to cause a breakdown voltage between either the first and second electrodes or between the second and third electrodes to be exceeded, current flows between the first and third electrode thereby short-circuiting the load and causing the fuse to break.

Abstract: A combination power and communication line protection apparatus includes a housing which contains a power line plug adapted to be received by a conventional wall power receptacle and a receptacle suitable for receiving a male line plug from equipment to be protected in addition to a pair of communication line or modular phone jacks into which an outgoing communication line may be received together with a data link communication line in parallel therewith. The apparatus provides an overvoltage protection for a pair of communication lines and an overvoltage surge protector for the power lines and utilizes the power line ground connection to provide the necesssary ground to protect the communication lines from overvoltages thereon.

Abstract: A method and equipment for protecting sensitive equipment against extended duration or transient over-voltages and their hazards. This is accomplished through a high-voltage fusing concept, a fast-acting clamping action and separate grounding points for power and control paths, respectively.

Abstract: Safety apparatus for a motor vehicle electric consumer having a temperature-dependent internal resistance, which includes a temperature indicating circuit for providing a signal which accurately indicates the consumer temperature to a threshold switch which actuates a switching device to interrupt current flow through the consumer whenever the consumer temperature exceeds a predetermined maximum value. The temperature indicating circuit either may be a consumer resistance measuring circuit such as a bridge circuit including the consumer in one leg thereof, or may be a consumer temperature replicating circuit, connected in parallel with the consumer, such as a special RC network. The switching device either may be a switch connected in series with the consumer, or a switch connected in parallel with the consumer, in which case the apparatus also includes an overcurrent device connected in series with the parallel combination of the switch and the consumer.

Abstract: An overcurrent protection system adaptable for use with power controllers the single or multi-phase ac, or dc types includes a load current sensing element in combination with an overcurrent sensing/inverse time delay circuit, a power switch and a crowbar circuit. The system also includes a drive circuit, a drive circuit input current sensor, a trip signal detector and a logic circuit. The overcurrent protection system, according to the present invention, uses the drive circuit to power the overcurrent sensing/inverse time delay circuit, to drive the power switch, and to provide a coupling path for an overcurrent fault signal across electrical isolation interface(s) thereof to the logic circuit. Thus, the need for a separate isolated power supply for powering the overcurrent sensing/inverse time delay circuit and the need for separate optical and/or electromagnetic isolation interfaces for coupling of the overcurrent fault signal are eliminated.

Abstract: A high-voltage crowbar circuit continually senses the load impedance and crowbars the output voltage applied to a load if the load impedance falls below a selected value. A differentiator circuit at the load senses variations in load voltage and can trigger the crowbar operation if the voltage variation as a function of time exceeds a preselected load.

Abstract: This disclosure relates to a wafer scale power interconnect system by which defective circuits on the wafer can be automatically disconnected from the power and ground lines supplied to each of the circuits. The disconnect device employs a gate between the power source and the circuit, which gate is controlled by a fuse that can be destroyed by an excessive current thereby opening the gate. The disconnect device may also be just such a fuse or a current limiter.

Abstract: A device for exciting a synchronous machine, comprises an exciter electrically connected to an exciting winding of the synchronous machine, a starting unit connected in parallel with the exciter and comprising at least one branch having a resistor and a thyristor switch placed in series. The control circuit of the thyristor switch has a threshold element. A protective thyristor is placed parallel to the branch of the starting unit and its control electrode is connected via the commutator of a current sensor of the starting unit branch to the control circuit of the protective thyristor. A safety device is inserted in series into the starting unit branch circuit.

Abstract: The invention relates to a current cut-out circuit for a high-voltage electric installation, a current source being located on an input side and an earth fault possibly occurring on its output side. The circuit is characterized in that between the input and the output, it includes for each phase, in series, a cut-out device (1) with a high arcing voltage, said device opening very rapidly, and a circuit-breaker (2) which opens rapidly and, shunt-connected between the input of the cut-out device with a high arcing voltage and earth, a resistance (4) for limiting an earthing current which passes via an automatic cut-out (3) with a very short closing time and a short opening time.

Abstract: To protect the battery in an automotive electrical system against over-charging upon failure of the voltage regulator to control current flow through the field of an automotive alternator, the field current is conducted through an interruptable network element, for example a fuse or a relay controlled switch. A voltage sensing network, for example a Zener diode, is connected to control current flow through a controlling element, for example a thyristor, which provides either an auxiliary current to burn out the fuse or a control current to the relay coil to interrupt connection to the field if over-voltage has been sensed. Simultaneously, an indicator lamp can be energized to indicate malfunction of the voltage regulator.

Abstract: Increased versatility in crowbar overvoltage protection for regulated power supplies is provided by a tracking circuit which allows setting the overvoltage limit at a predetermined increment above a programmable output voltage. In addition provision is made for programming up the crowbar protection circuit rapidly to anticipate the rise of voltage in the main power supply and for delaying the programming down of the protection circuit to allow the main power supply voltage to decay without triggering the protection circuit.

Abstract: A device, for protecting electrical equipment and appliances from electrical surges, having: male prong members to connect the device to an electrical outlet; a female receptacle to receive a plug of the equipment or appliance; current diverting means including a varistor and thermofuse for interrupting current at the female receptacle upon the occurrence on the line feeding the outlet of transient voltage spikes and surges exceeding a predetermined voltage level. The electrical outlets include power outlets and telephone connectors of the multi-prong or coaxial type. Equipment which may be protected by an embodiment of this device includes devices e.g. recorders, computer terminals, which may be connected to the telephone lines.

Abstract: A harmonic distortion attenuator in an AC power supply for reducing electrical energy consumption through the suppression of transient voltages in power supply lines or the like connected to the circuitry wherein a threshold voltage clamp, responsive to a transient, closes an electrical path between the power supply lines. A triac or current responsive device is provided in parallel with the threshold voltage clamp to shunt the current flow from the clamp when the current through the clamp rises above a predetermined limit.

Abstract: A conventional automatic electric circuit breaker is combined with a varistor to provide both overcurrent and overvoltage circuit protection. The varistor is connected between the load end of the circuit breaker and neutral to shunt to ground the currents associated with lightning induced voltage surges. As a fail-safe feature, abnormal leakage current drawn by the varistor under normal line voltage conditions directly and/or indirectly heats the thermal element of the breaker trip unit, ultimately tripping the breaker.

Abstract: Protection apparatus responsive to a fault condition in a high voltage, high current device to be protected; includes an ignitron and a hydrogen thyratron, connected in parallel across the device under protection, such that in event of a fault in the protected device, current is tandemly shunted away from the faulting device. Both the hydrogen thyratron and the ignitron receive simultaneous triggering signals from a fault-detection circuit upon the occurrence of a fault in the device under protection. Since the hydrogen thyratron responds to the fault-trigger signal more rapidly than the ignitron, it establishes a current-shunting path in the first fraction of a microsecond until such time as the slower-responding ignitron can become conductive and carry the brunt of the current to be shunted away from the faulting protected device.

Abstract: A protection circuit for producing one or more triggers in the presence of a monitored overvoltage condition employing photodiode networks for sensing the voltage overload, phototransistors responding to the photodiode outputs and operating gated semiconductors, which, in turn, discharge capacitors for trigger production. Separate networks are provided for each ac polarity operation. Monitoring may be with respect to supply voltage, power supply output voltage or one or more independent voltages.

Abstract: A device for protecting electrical appliances from electrical surges having male prong members to connect the device to an electrical wall outlet; a female receptacle to receive a plug of the appliance; a self-restoring, current diverting spark gap means for interrupting current at the female receptacle at a predetermined voltage level.

Abstract: The disclosed protector comprises a three electrode gas tube overvoltage protector serially connected with a heating element, the combination being connected in shunt across the load to be protected. Between that protecting shunt path and the source, a normally closed switch is provided which is responsive to the heating element and opens in the event of a sustained overvoltage condition. Accordingly, a prolonged surge which might otherwise destroy the gas tube and/or the protected load is isolated from both the shunt protection branch and from the load thus preventing damage to both.

Abstract: An over-voltage protection apparatus includes an over-voltage detector measuring the voltage between each energized conductor and a neutral or ground line associated therewith series connected between an A.C. power source and a utilization device and an over-current protection device, such as a circuit breaker, to disconnect the conductors from the energy source in the event the voltage on any one of the energized lines exceeds a predetermined threshold voltage. Suitable over-voltage detectors consist of any device which is non-conductive for all input voltages less than a threshold voltage and are conductive after the input voltage has exceeded the threshold voltage.The over-voltage protection apparatus described is applied to A.C. power circuits having at least one phase and at least two wires. Use of the apparatus to also provide protection in the event of an open neutral line condition, when unequal loads are present between at least two energized conductors and the neutral line is also described.