Abstract: A protection circuit for a semiconductor switch for switching a load is disclosed. Control circuitry is used for switching the semiconductor switch on in response to a switching signal and for switching the semiconductor switch off in response to a deactivation signal. A deactivation circuit is used for generating the deactivation signal. An overvoltage detector circuit responsive to a voltage at an output of the semiconductor switch that exceeds a predetermined value is used for generating an overvoltage signal. The overvoltage detector circuit includes a Zener diode that has its cathode coupled through a resistor to the output of the semiconductor switch and its anode coupled to the collector of the diode connected transistor. A first logic circuit is used for causing the deactivation circuit to generate the deactivation signal in response to the switching signal and the overvoltage signal.

Abstract: The fault latch and filter circuit used in a MOSgated driver for a high side power MOSgated device to turn off the MOSgated device high side output in response to a given fault condition is located in the high side of the circuit and in a floating well of a semiconductor chip containing the driver circuit. The fault latch and filter are connected to the output driver circuit through a gate which also receives the high side filter and latch which are operated by the input control logic circuits through a level-shift up circuit. The fault latch circuit has an output which is level-shifted down by a single PMOS device to a fault reporting latch circuit on the low side of the device.

Abstract: In accordance with the present invention, an output current limit circuit for protecting a power MOS output device of an integrated circuit from an excessive drain current comprises a power MOS device 110, a means 30 to sense a predetermined trigger current, and a means 20 to reduce a gate-source voltage on MOS output device 110 to a predetermined approximately fixed value. A drain current I.sub.D flows through power MOS device 110 from output terminal 102 in response to the gate-source voltage. A short circuit condition may allow an excessive amount of drain current I.sub.D to flow through output terminal 102. The gate-source voltage is reduced in response to sensing the trigger current. Reducing the gate-source voltage raises a drain-source resistance of MOS device 110 and reduces drain current I.sub.D so that MOS device 110 is not damaged by the short circuit condition.

Abstract: A current-limiting protector package for use in conjunction with telephone terminal blocks comprises a two-piece interfitting housing which is made up of two housing halves soncially welded together. A pair of tip or ring terminals is disposed within each housing half along with a current-limiting device in the form of a positive-temperature-coefficient (PTC) device of the conductive polymer type. Lower end portions of the tip or ring terminals project outwardly from the housing so as to be capable of electrical engagement with opposed sets of terminals provided upon the telephone terminal block, while upper end portions of the tip or ring terminals project outwardly from the housing so as to be accessible to a line test probe whereby the lines or circuits of the telephone terminal block can be tested in connection with their operative status without necessitating removal of the protector package from the terminal block.

Abstract: An apparatus for thermal protection of an electric motor is provided, including a monitoring device for generating a signal representative of the current in a conductor supplying electrical power to the electric motor. A control circuit processes the current signal and utilizes the processed signal and motor thermal parameters, including the thermal resistance and thermal capacitance of the rotor, to generate signals representative of the temperature of at least the rotor. A comparator circuit, which may be part of the control circuit, compares the temperature signals to reference maximum temperature signals and produces a control signal when the temperature signals and reference signals satisfy a predetermined relationship. The control signal may be applied to a contactor to interrupt current to the motor. A method for thermal protection of an electric motor is also provided, including thermal modeling of the rotor temperature.

Abstract: Protective circuit with a threshold circuit for discharging overvoltage surges to ground and with a low-value resistor positioned in a line wire at the subscriber's end meets a higher level of lightning protection by connecting a voltage-limiting component (V1, V2) in parallel with the low-value resistor (R1, R2). Such may a varistor connected in parallel with each of the series low-value feed or sensing resistors. The invention meets symmetry requirements, places low voltage requirements on low-value resistors and preceding parallel components, makes use of inexpensive voltage-limiting components and thereby results in cost saving.

Abstract: To enable the mounting of arrester in a small-sized package of a resin-sealed type for general use, such as a T0-92 package or a T0-220 package, by modifying the arrangement of diodes and thyristor there is provided: a diode-bridge thyristor type of semiconductor arrester, comprising: a pair of opposed metal plates (20, 21); a thyristor (T1) between the metal plates (20, 21); three pairs of diodes (D1, D2: D3, D4: D5, D6) between the metal plates (20, 21); and three leads (22, 23, 24), each provided between each pair of diodes.

Abstract: A photo chopper circuit consisting of a photo chopper, an overvoltage detection/control device, a power switch, and a protective diode for connection to the power supply line, voltage detection line, and ground terminal of a satellite antenna allocator, wherein if the photo chopper is erroneously connected to the voltage line of the satellite antenna allocator for motor drive or the power supply line of the satellite antenna allocator, the overvoltage detection/control device is turned on to switch off the power switch or, the protective diode reverses flow of voltage to protect the photo chopper.

Abstract: An integrated power module combining drivers and power devices includes a diagnosis module integrated with or connected to the integrated power module. That includes protectors. The protectors provides protection against power device failure, transistor stack failure, gate drive failure, power failure, and other conditions. In a first level of diagnosis and protection, a gate driver is responsive to hard faults, such as short circuit and under voltage conditions, to disenable the power devices, for example, switching transistors of an inverter. In addition, the first level of protection includes soft faults, such as detection of overcurrent and over temperature in the power device, conditions that are merely reported to the controller, whereby the number and frequency of the events can be monitored. The second level of protection also provided by the diagnostic module may include power interlock to ensure that full power is being delivered to the integrated power module.

Abstract: An electronic device offering protection against connection of a direct current power supply unit with reverse polarity includes a branch disposed between two potential lines and including a reverse biased diode and a first component sensitive to a flow of current. A first switch is disposed on the downstream side of this branch, on one of the potential lines. A control circuit has two terminals receiving a control signal and, connected in series between those terminals, a second switch and a second component sensitive to a flow of current. The first switch, normally open, is closed by the second sensitive element if the latter detects a flow of current. The second switch, normally closed, is opened by the first sensitive component if the latter detects a flow of current.

Abstract: In a protection circuit for protecting a plurality of chargeable electric cells by detecting overdischarge and overcharge by detection circuits for respective electric cells to control a protection switch upon detection, the detection circuit is a single chip device comprising an overcharge detection circuit and an overdischarge detection circuit to produce first and second detection signals, respectively, first and second terminals to be connected to an electric cell, third and fourth terminals for receiving first and second input signals, respectively, and fifth and sixth terminals for delivering first and second output signals, respectively. The first input signal and the first detection signal are processed by an OR gate to produce a first processed signal which is delivered to the fifth terminal. The second input signal and the second detection signal are processed by AND gate to produce a second processed signal which is delivered to the sixth terminal.

Abstract: An electrical device such as an electrical contactor interfaces at least one alternating current transformer having an output providing a signal proportional to changes in alternating current and includes at least one filter for filtering the output signal of the transformer. Each of the filters have an input connected to the transformer and an output having a signal proportional to the transformer output signal and inversely proportional to selected frequencies of the alternating current. The electrical device also has means for determining a value related to the alternating current using the output of each of the filters. The filter may have a resistor and a capacitor for filtering the transformer output signal in order that the filter is a low-pass filter. Alternatively, the filter may be a band-pass filter.

Abstract: The invention is a MOV based surge arrester that uses MOVs manufactured from a recently patented process. These new technology MOVs are significantly more uniform in their composition, resulting in more uniform performance. The uniform performance characteristics allow MOVs to be utilized parallel more successfully, eliminating many of the previous problems encountered. Instead of attaching wires to each MOV, the MOVs are packaged by placing them between a pair of contact plates, preferably manufactured from aluminum. The pair of plates are connected together and tensioned using non-conductive nuts and bolts. This packaging significantly increases the surface area between the contact plates and the MOVs. Wiring is minimized. Also, the use of the metal plates increases the ability of a surge suppresser to remove the heat generated in severe over-voltage situations. Additional plates can be utilized to increase surge arrestor surge current capability.

Abstract: A static protection circuit for a semiconductor integrated circuit device which provides static protection for an integrated circuit driven on multiple different power supply voltages is provided.The static protection circuit comprises a transistor having its two controlled terminals connected to each of the power supply lines and a GND line, respectively, and its control line connected to one of said controlled terminals; and a transistor having its controlled terminals connected to each of said power supply lines and its control terminal to which a nonconductive voltage is applied.

Abstract: A leak detector and circuit interrupter for detecting the presence of a liquid in the base of a dispenser containment box and interrupting the supply of electrical power when such liquid is detected is disclosed. There is a user enableable circuit for selectively enabling the pump and an override circuit which is operable when enabled to disable the user enableable circuit. An optical liquid sensing probe is positioned near the bottom of the containment box with optical coupling to the override circuit. The optical probe is coupled to a light emitting diode, a photosensitive transistor, and includes a light path with at least one total internal reflection surface normally coupling the light emitting diode and the photosensitive transistor. The probe normally maintains the override circuit in an ineffective state, but, when the light path is interrupted by an accumulation of liquid in the bottom of the containment box, changes state thereby enabling the override circuit and disabling the pump.

Abstract: A circuit tester comprising a ground fault circuit interrupter having two pair of leads connected to opposite sides of the interrupter in series for connecting the ground fault interrupter between an electrical circuit and a power source to indicate current leakage in an amount greater than about 0.005 amperes, a method for utilizing the circuit tester for detecting amperage leakage in the circuit, and an electrical circuit which will be interrupted whenever there is ampere leakage above that magnitude.

Abstract: An object of the present invention is to provide a thyristor valve arrester capable of measuring leakage currents of arrester elements in a simple construction and a DC power transmission thyristor valve having it used therein.A multiple of laminated arrester sets are arranged in parallel with a multiple of thyristor valves. Each arrester set is made of a plurality of arrester units arranged in parallel. Each adjoining arrester sets has through an insulator an inter-stage connecting conductor therebetween at a position corresponding to the respective thyristor valve terminals. An end of each arrester set and the respective inter-stage connecting conductors have a leakage current ammeter and a surge counter connected therebetween in electrical parallel. Each inter-stage connecting conductor and the respective thyristor valve stage are connected together by a thyristor valve connecting conductor.

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: An arrangement for protecting an electrical circuit such as a telephone circuit from a voltage transient comprises a voltage clamp or foldback device (3) arranged to be connected between a current-carrying line (1) and ground (1'), a capacitor (2) in series with it, and an inductance (4) series connected in the line. During normal operation the arrangement acts as an LC filter whose high frequency break-point is determined by the capacitance of the voltage clamp or foldback device (3) and the value of the inductance (4) which are chosen to give a break point of 1 kHz to 10 MHz. However, when the arrangement is subjected to a voltage transient, the voltage clamp or foldback device (3) fires causing the break-point to fall to a value determined by the values of the capacitor (2) and inductance (4). The arrangement may be used, for example, to protect the circuit against a rapid voltage drop caused by the firing of another circuit protection device such as a gas discharge tube 5.

Abstract: The present invention relates to an apparatus and method for distributing electrical power from power substation circuits. The apparatus of the present invention is responsive to overcurrent conditions and selectively actuates a switching network so as to restore power to at least a portion of the users connected to the faulty circuit of the power distribution system.