Abstract: An input protection device is presented for improving I/O electrostatic discharge ESD tolerance. The present invention protects a selected device by providing a sufficient potential difference between the substrate and the source of the device in question to protect it against an electrostatic discharge. In one embodiment of the invention, a resistor is placed between the substrate and the internal V.sub.SS connection. All V.sub.SS to substrate contacts have to be removed for internal V.sub.SS busses to be maintained at a predetermined resistance between the substrate and V.sub.SS. In other embodiments of the invention, an active device is placed between the substrate and the internal V.sub.SS connection. As with the first described embodiment, all V.sub.SS to substrate contacts have to be removed for internal V.sub.SS busses to be maintained at a predetermined resistance between the substrate and V.sub.SS. The active device presents a high impedance when not powered on and is very conductive when powered on.

Abstract: In a control circuit for controlling a power transistor included in a power device, the transistor is turned-off when a drop of a control voltage level or overcurrent in the power transistor is detected. Signals for discriminating the overcurrent from the voltage drop are generated and individually outputted from the control circuit, whereby the reason why the transistors were turned-off can be monitored. After a predetermined time period has passed from the overcurrent had been detected, the transistor is automatically turned-on to recover the operation of the transistor. A capacitor for supplying the control power voltage is re-charged during the time period. It is not necessary to carefully determine the on/off timings of the input signal for waiting the recovery of the control power voltage.

Abstract: This series-capacitor compensation equipment comprises a series-capacitor bank in series with a power line and an overvoltage protection circuit for the capacitor bank comprising the series combination of a surge arrester and electric bus structure connected in series with the power line and in parallel with the capacitor bank. The surge arrester includes metal-oxide varistor elements which impart a relatively high resistance to the arrester when the voltage across the arrester is in a normal range and a relatively low resistance when the voltage across the arrester rises to a predetermined value that produces arrester operation. The capacitor bank will discharge through the overvoltage protective circuit should a varistor element fail during arrester operation.

Abstract: A voltage doubler (2) having a series arrangement of two smoothing capacitors (C1,C2), is able to use less expensive smoothing capacitors (C1,C2) having a far lower rated voltage which is only slightly above the maximum voltage occurring during normal operation. To this end, a first and a second over-voltage prevention circuit (30,31) are coupled across the smoothing capacitors (C1,C2) of the voltage doubler (2) to protect the smoothing capacitors (C1,C2) against over-voltage if one of the smoothing capacitors (C1,C2) is short-circuited. The first and the second over-voltage prevention circuit (30,31 ) may both be an over-voltage detector, or an under-voltage detector each being coupled across one of the smoothing capacitors (C1,C2). It is also possible to combine an over-voltage detector coupled across one of the smoothing capacitors (C1,C2) to an under-voltage detector coupled across the same smoothing capacitor (C1,C2).

Abstract: A disconnect switch circuit for disconnecting an under-voltage battery from a hard disk drive connected between a voltage supply line and ground includes a MOSFET device connected between the battery and the voltage supply line, control means responsive to the supply voltage on the voltage supply line for generating a control signal powering the gate of the MOSFET switch. The control signal turns on the MOSFET switch when the supply voltage is in normal condition and turns off the MOSFET switch when the supply voltage drops below an under-voltage limit, thereby beginning head retract in the hard disk drive.

Abstract: A surge protector is adapted for a broadband coaxial system in which electrical signals having a frequency range from DC to one gigahertz are transmitted. The surge protector has a pair of coaxial cable connectors, a surge protection device, and a fail-short mechanism. The fail-short mechanism has a first operating condition in which the center and outer conductors of the coaxial cable connectors are isolated from each other and a second operating condition in which the center and outer conductors of the coaxial cable connectors are conductively coupled to each other. The impedance of the fail-short mechanism allows the surge protector to have an insertion loss with a magnitude not greater than about -0.2 decibels and a return loss having a magnitude of at least about -20 decibels, and the fail-short mechanism is adapted to conduct a fail-short current having a magnitude of at least about 30 amperes for at least about 15 minutes when the fail-short mechanism is in its second operating condition.

Abstract: Circuitry (10) and structures (30) are provided for electrostatic discharge protection. A first bipolar transistor (Q1) has a collector electrically coupled to a first node (12), a base electrically coupled to a second node, and an emitter electrically coupled to a third node (14). A second bipolar transistor (Q2) has a collector, a base electrically coupled to the second node, and an emitter electrically coupled to the first node (14). The second bipolar transistor (Q2) supplies a base current to the base of the first bipolar transistor (Q1) in response to the first node (12) reaching a threshold voltage relative to the third node (14), so that the first bipolar transistor (Q1) conducts current between the first (12) and third (14) nodes in response to the base current.

Abstract: An arrangement is described with several surge arresters arranged next to one another with their longitudinal axes substantially parallel. Each surge arrester is coupled to a common conductor rail via connecting lines which extend substantially radially away from the longitudinal axis of the surge arrester in a direction opposite to the position of exhaust openings on the circumference of the surge arrester. In the event of an electric arc, a current flowing through the connecting line thus generates a magnetic field which pushes the electric arc away from the surge arrester. The exhaust openings on each surge arrester are positioned so that the electric arc does not occur in the area between two adjacent surge arresters and is pushed away from the surge arresters by the components of the magnetic field. In addition, the direction of flow of the current in the connecting lines forms an angle smaller than 90.degree.

Abstract: A superconducting magnet abnormality detection and protection apparatus is for early and surely detecting abnormality in superconducting coils mounted on a vehicle and protecting the superconducting coils. Magnetic flux detecting devices are mounted inside an outer vessel, which is a vacuum container of a superconducting magnet, so as to be opposite to the superconducting coil. Voltages induced in the magnetic flux detecting devices are detected. Voltage signals are led to a decision device. By monitoring the change of the voltage signals with time in a comparing judgment device, it is determined whether there is an abnormality. If there is an abnormality, an alarm indicator informs of an abnormal state, and a protection device takes protection measures such as interruption of the current of the superconducting magnet. Owing to such configuration, heat does not penetrate from the outside into the superconducting coil via instrumentation lead wires of the magnetic flux detecting devices.

Abstract: A contactor control system for a DC electric power system for reducing contactor tip contamination from dry-switching includes a first switch connected in circuit between a power source and a controller for enabling the controller upon closure of the first switch. A PTC resistor is connected between the first switch and a filter capacitor whereby charging current is supplied to the capacitor upon closure of the first switch. A solid-state switch is connected in series circuit with an electromagnetic actuator of a contactor having power contact tips in circuit between the power source and a load. The series combination of the actuator and solid-state switch is connected in parallel circuit with the filter capacitor.

Abstract: A circuit for detecting phase imbalance in a three phase electrical system. The circuit includes a three phase current transformer or three separate current transformers for monitoring the current flowing in each phase of a three phase electrical system. The current transformers provide an induced current proportional to the monitored current. The induced current passes through a full-wave bridge rectifier which produces a voltage output proportional to the induced current. This voltage signal is passed to a two pole Sallen-Key filter which allows a desired signal having a particular frequency range to pass through and blocks the passage of an undesired signal having a particular frequency range. A scaling circuit then receives a portion of the desired signal and produces a scaled average signal which is of a preselected magnitude lower than the desired signal.

Abstract: An integrated circuit breaker having several accessory functions along with automatic overcurrent protection, allows selection between the various accessory functions in different combinations. Separate switches are arranged on the circuit breaker to allow factory as well as field selection of the accessory function combinations.

Abstract: For overcurrent protection of a switch-mode power supply in a high power audio amplifier, an active feedback overload shut-down circuit acts though a control input of a PWM (pulse-width modulator) in the switch-mode power supply. In a multi-output switch-mode power supply, e.g. a dual-rectifier supply providing .+-.53 volts and .+-.100 volts suitable for a class H amplifier, instantaneous currents in each of the two rectifier circuits are monitored by primary windings of a current-sensing transformer, providing from its secondary winding a signal that is rectified and monitored by a comparator-timer for current overload at a predetermined threshold. The primary windings are made to have a particular turns ratio so as to proportion the protection sensitivity for each dc output voltage. Upon sensing overload from either rectifier circuit, the comparator-timer applies a shut-down signal to the PWM, shutting down the power supply safely for a predetermined time period, e.g. 17 seconds.

Abstract: The disclosure relates to the methods and devices that enable series type buses to be protected against the consequences of a short-circuit in the decentralized units connected to this bus. There are provided means to detect the equalization of the potentials of the data wires and means enabling the disconnection, under the control of these detection means, of the decentralized unit responsible for the short circuit. A device is also provided to short circuit the supply wires of the bus according to a predetermined sequence in order to inform the central processing unit of the disconnection of said decentralized unit. The disclosure enables the protection of the central processing unit and of the decentralized units, connected to the bus, that are not malfunctioning.

Abstract: A fully automatic, photosensor-controlled time switch device, which includes a control box having an input port connected to power supply and an output port for connecting the load to be controlled, and a control circuit installed inside the control box and connected between the input port and the output port, the control box consisted of a photosensor, a set of relays, a multiple contact switch, a time control switch, and a load switch for controlling the operation of the load automatically at a predetermined time period.

Abstract: Surge protection for a data transmission line, typically a telephone line including two data signal conductors, incorporates a primary protector circuit for high voltage, high energy surges and a secondary protector circuit for low voltage surges. The primary protector circuit includes a normally non-conductive "breakdown" or "crowbar" device having a high breakdown voltage, a solid-state triac, or a thyristor, driven conductive by a surge exceeding its breakdown voltage; the crowbar device is connected from one or both conductors to ground. An inductance is connected in the circuit to extend the time in which the circuit reduces a surge to near zero voltage, and thus dissipates power from the surge. The second protector circuit includes at least one avalanche diode, Zener diode, or other threshold device in parallel with the primary protector circuit.

Abstract: A miniature station protector module for communication systems includes a hollow housing having a top surface and open bottom. A pair of line terminals and ground terminals are disposed in the housings top surface and extend inside the hollow housing, with the ground terminal disposed intermediate the pair of line terminals. A non-conductive printed circuit board with conductive paths thereon is affixed to the pair of line terminals and the ground terminal. A holding assembly is affixed to the ground terminal within the hollow housing and is adapted to receive a surge arrester therein. The surge arrester has at least a pair of electrodes and a ground terminal, with the ground terminal being an electrically conductive contact with the housing ground terminal, each one of the pair of surge arrester electrodes are in electrically conductive contact with one of the pair of line terminals. A protective housing circumscribes the surge arrester means and portions of the holding assembly means.

Abstract: A branch protection circuit is provided to isolate a power network from a faulty load such as an overcurrent condition. The circuit employs a current-sense field effect transistor formed from two power field effect transistors integrated onto the same silicon substrate. The current-sense-FET is provided to detect if the electrical current in the larger FET has exceeded a predetermined threshold level. The circuit does not measure the specific current flowing through the transistors, and the circuitry employed to detect if the threshold current level is exceeded is significantly less complex than circuitry otherwise required to determine a specific current flow through one of the transistors.

Abstract: A system and method for protecting relay contacts from erosion utilizes a sensor which senses voltage change in a switch controlling a load relay. In response to operation of the switch, the sensor sends a current to a set of pass transistors which are connected in series to the load power source and the load to turn off the transistors thereby cutting off load current flow to the load. A delay element is connected in series between the sensor and the set of transistors which cuts off the current flow to the set of transistors for a period of time selected to enable the load relay contacts to fully close or fully open before conducting electrical current therethrough.

Abstract: An arc suppressor for a sidactor type protective device wherein the sidactor type protective device comprises a sidactor body portion, two end line terminals, a central ground terminal, and a fail-safe mechanism mounted upon the terminals of the sidactor in order to shunt or short-circuit the sidactor under overload conditions. The arc suppressor comprises a housing or cap tightly enveloping or encasing the sidactor body portion so as to enhance the strength thereof and thereby maintain the structural integrity of the body portion by effectively preventing any cracking thereof under overload conditions. The prevention of the cracking of the sidactor body, in turn, insures that any plasma gas or cloud generated within the sidactor body under high-voltage overload conditions is contained within the sidactor body and does not escape therefrom so as to otherwise present an environment conductive to arcing between the terminals of the sidactor.