Abstract: A line protector for a communications circuit comprises a generally cup-shaped housing; and a generally disc-shaped solid state overvoltage arrester having electrodes formed at axially oppositely facing surfaces thereof for connection to a line circuit and a ground circuit respectively. An elongate contactor extends into the housing for contacting a first one of the electrodes and projects outwardly of the housing for contacting one of the line circuit and the ground circuit. An insulator member receives and positions the solid state overvoltage arrester with the other of the electrodes thereof in contact with a closed end of the cup-shaped housing and with the first electrode in position for contacting the contactor. An elastomeric member surroundingly engages the contactor and is surroundingly engaged by the cup-like housing for retaining the contactor, the insulator member and the overvoltage arrester in asembled condition within the housing.

Abstract: A voltage limiter arrangement, including a voltage limiter including a central connecting lead and outer connecting leads positioned on each side of the central connecting lead. A surge arrester magazine is provided including a surge arrester magazine housing and contacts for connection to leads of the voltage limiter. The surge arrester magazine is provided with an open upper end. A receiving member is provided including a receiving opening for accommodating the voltage limiter, the receiving opening including a bottom wall with openings for each of the central connecting lead and the outer connecting leads. The receiving member includes guide elements for guided insertion of the receiving member into the open end of the arrester magazine for guided connection of the central connected lead and the outer connecting leads with contacts of the surge arrester magazine. The surge arrester magazine open upper end preferably includes an inner wall contour corresponding to the guide means of the receiving member.

Abstract: A solid state circuit interruption arrangement in a distributed power network provides fast and reliable circuit interruption. A common power source provides power to a plurality of loads via respective current paths. A main circuit breaker and a plurality of solid state circuit breakers are arranged to interrupt the current paths in response to command signals sent from a central controller. Current sensors and voltage sensors are coupled to the current paths for monitoring purposes. An automatic controller responds to any of the current sensors detecting a fault condition by automatically generating a command signal, which forces the associated solid state breaker to interrupt the associated current path. Thereafter, the controller automatically generates a signal to the main circuit breaker to interrupt the power provided from the common power source in the event that the associated current path is not interrupted by the solid state breaker.

Abstract: A solid state relay includes a protective input stage at its control terminals to isolate the control circuit from line voltage or line current in the event of relay failure. The protective circuit includes a series combination of a voltage responsive element and a current responsive element. The current responsive element connects to the input or control terminal of the solid state relay and the voltage responsive element connects to ground. The interconnection of the current responsive element and voltage responsive element serves as the device input terminal for connection to a control circuit. In the event of relay failure, the voltage responsive element reacts to the increased voltage by providing conductivity, by way of the current responsive element, between the solid state relay input terminal and ground.

Abstract: Arrangement for arcless interruption of a-c load current in response to a current interruption command. Separable contact means serially connected with controlled impedance means, and parallel connected diversion means are intermediate the a-c source and the load. The controlled impedance comprises field effect transistors (FETs). Since FETs usually have only a single inherent junction, at least a pair of the FETs are oppositely poled so that load current can be cut off notwithstanding the direction of current flow when interruption is commanded. The pair of FETs may be connected back to back. An alternative embodiment has two branch circuits each comprising a FET and a separable contact means. Upon interruption load current is sequentially transferred from one to the other branch circuit and then to the diversion means.

Abstract: A high-speed high-voltage FET current interrupter which opens the cathode circuit of microwave tubes when internal tube arcing occurs. By removing the detrimental fault current which causes degradation to the microwave tube body and grid, the longevity of the microwave tube and the pulse energy storage capacitor is greatly increased over those transmitters which use dissipative crow bar circuits. Even more important is that the transmitter reset time after an arc occurs is orders of magnitude faster than transmitters using crow bars or primary power interrupters when arcing occurs--an important feature when engaged in a "dog fight".

Abstract: A connection control device for controlling the connection of a small generator unit, which is installed at the consumer's location, to an electric power system. The connection control device detects variations in frequency components which result from interruptions in the distribution of electric power to the consumer from the electric power system. When a significant variation in a frequency component is present, the connection control device disconnects the consumer from the electric power system in order to prevent injury to line workers.

Abstract: An apparatus for protecting electrical installations against transients includes one or more devices comprising a network of varistors connected through a gas discharge tube to live, earth and neutral conductors. The varistors each have a terminal connected to an associated pole of the tube and the other terminal to the associated conductor. The apparatus may have three devices connected in cascade and preferably, inductances connected in series in the live and neutral conductors between the devices and the load. Preferably, varistors interconnect the conductors between the inductances and load. Relatively cheap and efficient apparatus for discharging transient over-voltages is provided.

Abstract: A simplified solid state transient voltage and overcurrent protector for telecommunications equipment providing uniform protection characteristics between telephone lines and between either line and ground is shown in which two symmetrical thyristor chips are mounted with their normal common layer connected together on an enlarged heat sink. The assembly, together with current limiting PTC elements is encapsulated to form a dual-in-line package.

Abstract: An appliance leakage current interrupter (ALCI) comprising a ground fault detecting circuit and a trip mechanism that is automatically actuated in response to the presence of a ground fault. Actuation of the trip mechanism automatically interrupts the flow of current to the appliance and permits movement of a reset button to take place to visually signal that current to the appliance has been interrupted, although interruption of current flow is not in any way dependent on movement of the reset button, whereupon if movement of the reset button is prevented for any reason, flow of current to the appliance is still automatically and instantaneously interrupted in response to the presence of a ground fault. A test button is provided, actuation of which simulates a ground fault to enable a user at any time to determine whether the ALCI is working properly.

Abstract: A water sensing type power breaker circuit is incorporated into an electric appliance such as a hair dryer or the like and is used to cut off a power supply to prevent an accident due to an electric shock immediately when the electric appliance is dropped into the water.A water sensing type power breaker circuit includes first and second contacts having one polarity connected to a power supply and the other polarity connected to a load, an impedance element circuit including first and second impedance elements connected in series each other and which is connected in parallel with the load, a water sensing element made of an electrical conductor connected to an intermediate point between both the impedance elements through a conductor, and a relay for detecting a current flowing through the conductor to open the first and second contacts when the current flows through the conductor. The relay is held by itself so that the first and second contacts are opened.

Abstract: A motor drive circuit comprises a motor, a DC source connected to said motor, first and second switching elements turned on and off to control a current flowing to the motor having one terminal connected to a common connecting point of the first and second switching elements, and when the current flowing to the motor is stopped by the first switching element, the second switching elements is turned on to break the motor, a reverse current bypassing circuit connected to at least one of said first switching element and said second switching element for bypassing a reverse current supplied by the DC source, a reverse current blocking circuit connected to said second switching element for blocking the reverse current and a surge absorbing circuit connected to at least one of the first switching element, the second switching element and a series circuit of the second switching element and the reverse current blocking circuit for absorbing a surge generated when the first switching element is turned off in response

Abstract: An arrangement for opening a circuit coupled to an electrical power source associated with a neutral circuit. The arrangement includes a bi-stable latch for electrically engaging and disengaging a pair of contacts in response to the value of the sum of currents in the circuit and the neutral circuit exceeding a predefined limit. The arrangement also includes a mechanism for opening and closing a pair of main contacts which are used to open and close the circuit. The mechanism can be operated by a shunt trip solenoid such that the solenoid causes the operating mechanism to open the contacts when the contacts of the bi-stable latch are closed.

Abstract: A method for initiating a rapid current limiting device utilizing a device which integrates the current during a selected time interval. The equivalent RMS current is predicted based on the integration to generate a signal which initiates the current limiting device when the predicted RMS current exceeds a preselected value.

Abstract: A current of an alternating current electric line is detected by a current transformer, the output of the current transformer is rectified by a rectifier, a series connection of a switching means and a resistor is coupled across the output terminals of the rectifier, a control circuit composed of a capacitor, a comparator and a reference voltage generator is coupled in parallel to the switching means through a diode, when the DC output voltage exceeds a predetermined voltage based on the reference voltage of the reference voltage generator, the comparator outputs a signal for closing the switching means, and the voltage which is applied to the control circuit is limited to a predetermined value.

Abstract: A device for suppressing electromagnetic static and voltage surges induced on radio frequency transmission cables is disclosed. The device comprises a blocking capacitor connected to prevent the conduction of DC currents but to permit the transmission of radio frequency signals. An inductor coil is connected between one side of the capacitor and ground. The inductor coil is of a value that blocks conduction of radio frequency signals but allows static and low frequency DC voltage surges to be conducted to ground. A gas discharge unit is also connected from the same side of the capacitor to ground. The discharge unit is a secondary discharge device that only operates when the transient speed and magnitude of the surge is sufficient to cause a back emf to develop across the inductor coil above a predetermined limit. The gas discharge unit assures that the capacitor is not damaged by the back emf.

Abstract: The invention relates to a circuit arrangement for switching current from a contact to a thyristor connected in parallel to the contact. In the inventive circuit arrangement ohmic resistances (7, 8, 9, 10) are connected in parallel to the contact (1), whereby each ohmic resistance (7, 8, 9, 10) can be individually disconnected by means of a delayed-opening contact (3, 4, 5, 6) and the disconnection times are staggered. In this manner, it is possible to accomplish stepwise current switching and thus reliably prevent arcing at the contact (1).

Abstract: Overvoltage protection circuit (10) has a power transistor (11) that drives an inductive load (19). A resistor (16) is connected between an output electrode (14) of the transistor and a control electrode (12) of the transistor, and a constant current source (18) is also connected to the control electrode. The resistor and constant current source determine an effective zener voltage to limit the maximum voltage which can exist at the transistor output electrode (14), and this is accomplished without the use of a zener diode while utilizing a minimum number of components. This effective zener diode voltage can be readily adjusted by adjusting either the magnitude of the resistor (16) or the constant current source (18).

Abstract: A circuit for limiting temperature without distortion in audio power amplifiers, comprising a temperature sensor for sensing the temperature in an audio power amplifier, and a variable-gain amplifier connected ahead of the audio power amplifier circuit and having a gain control input connected to the temperature sensor to vary the input signal of the audio amplifier in a linear manner. A linear limitation of the power, and therefore of the temperature, is thus obtained in the audio amplifier without introducing distortion.

Abstract: A grid electrode voltage control aparatus is for a scorotron charging device having a corona discharge electrode operatively connected to a corona producing power source and disposed opposite a counter electrode, and a grid electrode disposed between the corona discharge electrode and the counter electrode. A shunt-regulated stabilized power supply is operatively connected to the grid electrode and has an output variably responsive to the intensity of current flowing through the grid electrode. A series-regulated stabilized power supply (preferably comprising a dc-dc converter and a current limiter) is operatively connected to the shunt-regulated stabilized power supply.