Abstract: A circuit for protecting the ac generator and/or load of a diesel-engine generator set is provided. Included is a circuit for measuring indications of the current in each phase of the ac generator, and a switching circuit for protecting the ac generator if the current in any phase is greater than a predetermined current for a predetermined length of time, or if the current in any phase is less than a predetermined function of the currents in each of the phases for the predetermined length of time. For diesel-engine generator sets which generate three phase 460 V at up to thirty amperes continuously, the preferred predetermined overcurrent for any phase of the ac generator is thirty-five amperes, and the predetermined length of time (to permit inrush currents) is five seconds. Preferably the current in any phase should be less than fifty percent of the average of the current in the three phases.

Abstract: A device for detecting a primary fault current at a three phase current system and converting the detected fault current into mechanical action for breaking the circuit includes circuitry for breaking the circuit in response to a selected secondary current substantially instantaneously rising to a predetermined level and a device for adjusting the predetermined level.

Abstract: A circuit protection device designed to protect a pair of electrical circuits by fracturing at such time as an overcurrent condition has occurred in a first of the circuits, this novel device comprising a substantially flat substrate of non-conductive, frangible material upon which a resistive component and a fuse conductor reside in an adjacent relationship on a common surface. The resistive component is part of a first circuit, and the fuse conductor is part of a second circuit. The resistive component, at the time of an overcurrent therethrough, becomes hot and causes a heating of the near surface of the frangible substrate.

Abstract: Disclosed is an electrical power system adapted to receiving power from a source of alternating current, typically a small alternator and supplying a direct potentially to a load. This power system contains protective circuits which control or shut off a portion or all of the electrical power system in response to abnormally high or low voltage conditions. The high voltage protection circuit short circuits the alternator in response to abnormally high load voltage. A second high voltage sensing circuit, locks out the main regulation and rectification circuit for a selected period of time after the over voltage sensing point is exceeded. The low voltage protection circuit abruptly reduce output to zero once the output voltage decreases to a minimum level. This voltage then remains at zero until the circuit is reset by an external signal.

Abstract: A vehicle storage battery protection system that senses a drop in battery voltage to a level at which the battery still retains sufficient power to start the vehicle. If the sensed voltage remains at or below this level for a time greater than the time normally required to start the vehicle, the battery is disconnected from the load and a hysteresis signal is provided to prevent a reconnection as the battery voltage begins to rise after the load has been disconnected. The load is automatically reconnected to the battery upon operation of the ignition switch to restart the vehicle. A reset circuit provides a small test voltage to the disconnected load, and senses a voltage drop caused by operation of the ignition switch to start the vehicle. This sensed voltage drop is detected and causes a main switch to reconnect the battery to the loads.

Abstract: An overtemperature sensing and signaling circuit for electronic trip units includes a voltage divider (16) and a trigger circuit (18). The voltage divider is formed of a first resistor (R1) and a positive coefficient resistor (PT1). The trigger circuit is formed of a first bipolar transistor (Q1) of the PNP-type conductivity and a second bipolar transistor (Q2) of the NPN-type conductivity.

Abstract: A transient protection circuit provides protection from high voltage transients appearing along a transmission line by sensing a predetermined threshold of the voltage developed thereon and opening the conduction path through first and second switching circuits in the transmission line. The switching circuits are implemented with first and second serially coupled transistors sharing a common drain and enabled by a control signal during normal operation. The first and second transistors each have a diode oriented to conduct from the source to the drain for bi-directional operation. During high voltage transient conditions, a sensing circuit detect a predetermined threshold of the potential on the transmission line and disables one of the first and second transistors which opens the conduction path through the first and second switching circuits thereby suppressing the surge currents flowing therethrough.

Abstract: An energy dissipation circuit for protecting a semiconductor integrated circuit from electrostatic discharge (ESD). The dissipation circuit provides an energy dissipation path between any combination of two pins of the semiconductor integrated circuit to be protected.

Abstract: Conductive polymer PTC compositions have improved properties, especially at voltages of 200 volts or more, if they are very highly cross-linked by means of irradiation, for example to a dosage of at least 50 Mrads, preferably at least 80 Mrads, e.g. 120 to 600 Mrads. The cross-linked compositions are particularly useful in circuit protection devices and layered heaters.

Abstract: A differential current circuit breaker is disclosed in operation with a transductor circuit. The transformer has a secondary winding which is coupled to a measuring resistor in series with a generator, in particular a square wave generator, for alternating magnetization. The circuit breaker includes an evaluation circuit coupled to a tripping mechanism that acts through a breaker mechanism on switching contacts in the conductors being monitored. The evaluation circuit is coupled to a tap between the secondary winding and the measuring impedance. The generator capable of setting the generator frequency within a larger frequency range than is required to compensate for tolerance adjustment in the generator itself.

Abstract: A protection circuit for a solid state instrument includes a plurality of fuses and a switching device arranged in parallel with the input capacitance of the solid state instrument, The fuses protect the instrument from high voltage surges, and the switching device protects the instrument from lower voltage surges. The fuses and the switching device are solid state devices and thus can be fabricated along with the solid state instrument.

Abstract: The interface circuit described comprises a plurality of control stages, each of which can detect and indicate a short-circuit in the corresponding load or the associated power transistor.In particular, the interface circuit is arranged to disable a transistor permanently when short-circuits occur repeatedly in the load in order to prevent damage to the transistor.

Abstract: A sampling frequency conversion apparatus having N (where N is an integer, which is two or more) sampling conversion means serially connected, each of the N sampling frequency conversion means comprising a first digital filter for outputting a signal with longer bit length than that of an input signal, and first sampling means for sampling a signal which is output from the digital filter at a sampling frequency, the sampling frequency decreasing as the stage of the sampling frequency conversion means becomes later. Thus, the earlier stages which should be operated at a high speed, the bit length of signals becomes short. In the later stages where the bit length becomes long, the sampling frequencies are decreased. Consequently, the apparatus can be operated at a high speed and constructed at a low cost.

Abstract: A device and method for interrupting current flow to an electrically-powered apparatus is disclosed. The device includes a means for detecting a selected value of a physical parameter associated with the operation of the externally powered electrical apparatus, a trigger circuit incorporating an integrated circuit, a firing device which responds to the trigger circuit by generating a conductive plasma, an electronic measurement circuit to prevent unwanted firing of the firing device and thin conductors which are destroyed by the firing device when the conductive plasma forms an electric arc between them. Current flow to the electrically-powered apparatus is thereby terminated.

Abstract: A current regulator circuit for shunting excess current from a current supply utilizes two separate shunting paths, depending on the amount of excess current on the supply line. The first shunting circuit is activated when the current exceeds some minimum level established by a zener diode. The second current shunting circuit is selectively activated by a switching circuit which compares the current in the first shunting circuit to a reference voltage that is proportional to the line current. This arrangement is advantageous in that it shunts excess current without generating significant levels of heat or adversely affecting current sensing devices.

Abstract: A surge protection apparatus, has a signal terminal, and first and second power supply terminals which are connected to the internal circuit to be protected, and first and second diodes which are connected between the signal terminal and the first and second power supply terminals, and a protective transistor acting as a discharge path for the surge voltage which is connected between the first and the second power supply terminals. As a result, even if the discharge capability of the internal circuit connected between the first and second power supply terminals is small, the surge voltage can be discharged in a short time through the protective transistor. Moreover, since the protective diode at the positive power supply side is connected to the power source of low impedance, the plural signal terminals will not be coupled by the junction capacitance. Thus, crosstalk does not occur between the plural signal terminals.

Abstract: A controllable semiconductor switching device having integrated overload protection of a load current path, including a switching section in the load current path and a multiplicity of main switching cells acting in parallel and having load-side terminals and non-load-side terminals including control terminals. The control terminals of the main switching cells are directly connected in a highly conducting manner among one another. A multiplicity of auxiliary switching cells are provided which carry a part of a total load current in parallel with the main switching cells in order to achieve an overload protection, and having load-side terminals and non-load-side terminals. The number of auxiliary switching cells are less than the number of main switching cells. The main switching cells and the auxiliary switching cells form the switching section.

Abstract: A fail-safe device is provided for an overvoltage protector element where the protector includes a body having first and second contact surfaces and a tip lead, a ring lead and a ground lead extending from the body. The fail-safe device includes a heat deformable dielectric base and an electrically conducted spring member having first and second contact ends. The base is disposed against the element body with the base having first and second spacer ends separating the spring's first and second ends from the protector body's first and second contact surfaces.

Abstract: The governor rope on an elevator is provided with an auxiliary brake which is a fail-safe brake and which operates to stop movement of the governor rope when the elevator car moves away from a landing with its doors open. The brake includes two rope gripper jaws in the machine room beneath the governor sheave, which jaws are held away from the governor rope by a solenoid so long as power is supplied to energize the solenoid. When the power supply to the solenoid is interrupted, the jaws are released to fall by gravity toward each other to grip the governor rope. The car emergency brakes are thus tripped and movement of the car stops. The brake may also be provided to control the counterweight governor rope.

Abstract: An analog-to-digital converter (ADC) having two cascaded A/D stages of the parallel type wherein the analog signal is compared with a set of threshold reference voltages. The first stage develops a set of most-significant bits and produces two analog residue signals: a normal residue corresponding to the difference between the analog input and the threshold voltage below the analog input, and a second residue corresponding to the difference between the analog input and the threshold voltage above the analog signal level. These two residue signals are amplified and directed to the second A/D stage. The sum of the residue signals equals one LSB of the first A/D stage, so that the two residues supply to the second stage information about the quantization error of the previous stage as well as the quantization step size to be used to define full-scale at the second stage.