Abstract: A method and a device for driving an electromagnetic consumer (device) which includes a movable element, in particular a solenoid valve for metering fuel into an internal combustion engine. Within a timing window, a switching instant is determined by evaluating the time characteristic of a variable which corresponds to the current flowing through the electromagnetic consumer. A clocked voltage control is provided within the timing window.

Abstract: A method is provided for controlling an electromagnetic actuator having an electromagnet including a magnetic core presenting a pole face and an electromagnet coil wound around the magnetic core, a return spring and an armature connected to an actuation mechanism and movable toward the pole face by a magnetic force of the electromagnet against the force of the return spring. The method includes: detecting a time behavior and/or value of current and/or voltage present at the electromagnet coil during a time period when the armature does not move relative to the electromagnet, and deriving a value corresponding to the actual ohmic resistance and/or inductance of the electromagnet coil from the detected time behavior and/or value from the detecting step for compensating changes in the ohmic resistance of the electromagnet coil.

Abstract: A microprocessor-based control for a solenoid operated device, wherein the microprocessor employs a tri-state output to achieve fast, precise control of the device without overburdening the microprocessor. The system has three selectable control modes: a first control mode in which the solenoid is de-energized, a second control mode in which the solenoid is fully energized, and a third control mode in which the solenoid is pulse-width-modulated. The various control modes are selected by the microprocessor and indicated by the logic level of a tri-state output. In the first and second control modes, indicated by first and second logic levels, the energization state of the solenoid is controlled directly by the microprocessor. In the third control mode, indicated by a third logic level, the energization state of the solenoid is controlled by an external PWM circuit based on PWM commands supplied to the PWM circuit by the microprocessor.

Abstract: The circuit arrangement for an auxiliary relay that actuates a starting relay for a starter device of an internal combustion engine includes a temperature measuring device (20) and a control and/or regulating circuit device (16,16') for controlling, in a turned-on state, an operating current (I) flowing through a relay coil of the auxiliary relay according to a temperature of the auxiliary relay or starting relay measured by the temperature measuring device (20) so that the operating current (I) and mean value of the operating current (I) are controlled according to the temperature. The control and/or regulating circuit clocks the operating current and can vary the duty cycle to reduce the power losses.

Abstract: A control circuit for electrical contactors, starters and the like which include one or more pairs of separable main contacts is controlled by an electromagnet assembly. In order to reduce, if not eliminate, audible noise generated by the electromagnet assembly, the electrical current to the electromagnetic assembly is regulated to minimize the rate of change of magnetic flux therethrough to thereby reduce, if not eliminate, audible noise. By regulating the electrical current to the electromagnet assembly, the power consumption of the electromagnet assembly is reduced which, in turn, reduces undesirable heating of a solenoid coil within the electromagnet assembly.

Abstract: A pulse width modulated drive circuit drives a solenoid operated valve in response to an input voltage signal from a control apparatus. The solenoid operated valve includes a coil that is energizable in response to energy received from the pulse width modulated drive circuit. The pulse width modulated drive circuit includes a pulse generator stage and an output stage. The pulse generator stage receives the input voltage signal from the control apparatus and a feedback signal from the coil which ultimately combine to form a control voltage in response to which the pulse generator stage generates a pulse width modulated signal whose duty cycle depends on the control voltage. The output stage receives the pulse width modulated signal from the pulse generator stage and generates in response thereto a pulse width modulated output signal across the coil. The pulse width modulated output signal has pulse width generally proportional to the control voltage and carries energy from a source of energy.

Abstract: A circuit breaker comprising a switch for controlling the connection of a load to a power source, the switch having a fixed contact and a movable switch contact supported on a pivotable switching member and resiliently biased away from the fixed contact. The circuit breaker includes a solenoid having a first winding for initially moving the movable contact towards the fixed contact and a second winding for holding the movable contact against the fixed contact, a fault detection circuit adapted to detect a fault at the load and in response to disable the solenoid, and a reset switch for initially enabling energization of the first winding and when the movable contact is sufficiently close to or in contact with the fixed contact for subsequently enabling energization of the second winding. The reset switch is arranged to be operated by a part of the switching member by virtue of the movement of the movable contact in order to control energization of the windings.

Abstract: An electric gun driver for controlling a solenoid within a dispenser which dispenses a liquid material, such as a heated adhesive, for application to packaging materials. The electric gun driver includes a switch mode power supply for receiving a wide range of input voltages so that the electric gun driver is adaptable to various power supply systems throughout the world. The improved electric gun driver also includes a computer for monitoring and regulating the operation of the dispenser device, a power circuit, and a hysteresis band modulator for receiving a reference current from the computer and a feedback current from an operational amplifier so as to provide a modulation signal to the power circuit. The power circuit includes two switches in the form of insulated gate bipolar transistors respectively controlled by gate driver and detector circuits so as to modulate the solenoid current for controlling and regulating the dispenser.

Abstract: A power supply circuit, using direct current or rectified alternating current sources having output and return supply lines (a, b), for a coil of an electromagnet having at least one principal winding (B1) and a secondary winding (B2). The power supply circuit includes a first semiconductor element (T2) having a gate and a source drain path and capable of providing or blocking a supply of current to the secondary winding (B2), the source drain path connected between the secondary winding (B2) and the return supply line (b); and a switching means (10) connected between the primary winding (B1) and the gate of the first semiconductor element (T2).

Abstract: An engine fuel system including a solenoid actuated fuel control valve (16) which is energized to cause fuel delivery to the associated engine. The valve is initially closed to achieve pilot delivery of fuel by a high current pulse supplied to the solenoid winding (7) and is then allowed to open under the influence of a spring, the opening movement of the valve member being controlled by supplying current to the solenoid winding. Finally by supplying further current to the winding the valve member is closed to achieve closure of the valve for the main delivery of fuel.

Abstract: A method of energy-saving regulation of the attraction of an armature of a switching magnet, particularly an electromagnet for a control element in an internal combustion engine, wherein a medium voltage U.sub.Z is formed by switching to the lowest-available supply voltage U.sub.V, the medium voltage being sufficient to regulate a current I.sub.S in order to build up the magnetic field of the electromagnet.

Abstract: An inductive load driver circuit with shared flyback protection includes a first transistor (209) which drives a first load (229), and a second transistor (231) drives a second load (251). A first clamp voltage steering diode (217) is coupled between an input terminal (207) of the first transistor (209) and a zener diode (203), and a second clamp voltage steering diode (239) coupled between an input terminal (233) of the second transistor (231) and the zener diode (203). A power supply terminal (201) is coupled to the zener diode (203).

Abstract: The control system for a linear solenoid valve controls output of an oil pressure according to a current value to be fed to the linear solenoid which operates the linear solenoid valve. A solenoid current monitor detects the current value fed to the linear solenoid and an IG voltage monitor detects the voltage level of the battery. A linear solenoid current value setting unit sets a target current value according to a target oil pressure level and a duty ratio setting unit sets a duty ratio for applying the battery voltage to the linear solenoid on the basis of signals coming from the current monitor, the voltage monitor and the current value setting unit. A solenoid driver applies the battery voltage to the linear solenoid for a predetermined period in accordance with the duty ratio set by the duty ratio setting unit.

Abstract: An electronic circuit, and corresponding method, for controlling the closing velocity of electrical switchgear, includes an actuator and a current detection circuit that detects whether an optimum amount of current is flowing through the actuator. When the optimum amount of current is detected, a current optimizing resistor is inserted into the path of the current flowing through the actuator, thus limiting the current flowing through the actuator to the optimum amount. This, in turn, limits the closing velocity of the electrical switchgear and minimizes contact bounce.

Abstract: A solenoid driver (10) capable of detecting the operational status of a solenoid (12) including the position of an armature within a solenoid coil and an operational method. The solenoid driver (10) generates a first solenoid current within the solenoid (12) and measures a first decay time t.sub.1. The first solenoid current is insufficient to pull the armature into the coil of the solenoid (12). A comparator circuit (22) continuously monitors the solenoid current and initiates a timer within a counter circuit (34) to compute the first current decay time. A second solenoid current is generated within the solenoid (12) that is sufficient to pull the armature into the coil of the solenoid (12). The second solenoid current is turned off and a second decay time t.sub.2 is measured. The decay times are stored in storage registers (R1, R2) within a controller (36). The controller (36) compares the measured decay times with stored values and outputs the armature position information over a communications bus (34).

Abstract: A method is provided for adapting a control for an electromagnetic actuator for actuating an adjusting device in a system, in particular for actuating a cylinder valve in a piston engine, to operation-dictated changes in the electromagnetic actuator. The electromagnetic actuator includes at least one electromagnet, a restoring spring, an armature operately coupled to the cylinder valve and disposed for movement counter to the restoring spring. The electromagnet is energized, during an idling phase of the engine, with a current having a path deviating from a normal current in a normal mode of operation. Portions of a course over time of current through the electromagnet are detected. The detected course of current is compared with a predetermined curve. The control for the electromagnet for the normal mode is adapted if there are deviations between the detected course of the current and the predetermined curve.

Abstract: An electromagnetic force generated in a valve driving apparatus is rapidly decreased when a valve body moves to a position close to the end of its stroke so that a shock generated when the valve body reaches the end of the stroke is reduced. The valve body is movable between opposite ends of its stroke so as to open and close a valve provided in an internal combustion engine. An electromagnetic coil generates an electromagnetic force exerted on the valve body. A current supplied to the electromagnetic coil is controlled in accordance with an operational condition of the internal combustion engine. The current flowing in the electromagnetic coil is rapidly decreased when the valve body approaches the end of its stroke.

Abstract: A pulse-width modulation control system having a power source, driver circuits connected to the power source, and two solenoids, such as those for a vehicle automatic transmission, connected to the power source through the driver circuits, and pulse trains of a predetermined PWM duty ratio are supplied. The supplied currents are detected and A-D converted. In the system, one pulse train lags behind the other at the leading edge. When PWM controls two solenoids at the same time using an on-board microcomputer, two voltage memory circuits are additionally needed, since the microcomputer ordinarily has only one A-D converter. With the arrangement, only one voltage memory circuit is needed, rendering the system configuration simple.

Abstract: An under voltage trip device for low and medium voltage breakers is disclosed. A first power supply receives unregulated power from a control voltage supply which is rectified and regulated with portions of the power supply monitored by a processor. The output of the first power supply is supplied to a second power supply which allows pulsing modulating power to be supplied to a solenoid connected thereto. The current supplied to the solenoid is measured and calculated by the processor and stored therein as well as being compared to stored values, thereby determining solenoid armature position and predicting or warning of solenoid failure. Connected to the second power supply is a third power supply which operates in a voltage regulator supply mode and a switcher mode during start-up and continuous running operation respectively, such mode being controlled by the processor.

Abstract: An electrical circuit applies an oscillatory electrical current to a coil of a solenoid in order to cause the solenoid to move in response to a command signal. The circuit includes a signal divider for generating an upper peak current signal value from the command signal and a lower peak current signal value which is a fixed percentage of the upper peak current signal value. A current sense resistor generates a current sense voltage representing current through the coil. A first comparator compares the current sense voltage to the upper current signal value. A second comparator compares the current sense voltage to the lower current signal value. A set/reset flip-flop latches a current driver on and off. A current driver applies a driving current to the solenoid coil as a function of output signals generated by the first and second comparators so that the coil current will have a lower peak current value which is substantially a fixed percentage of the upper peak current value.

Abstract: A method of controlling movements of an armature in an electromagnetic circuit which includes at least one holding solenoid applying magnetic forces to the armature and at least one resetting arrangement for applying a resetting force to the armature. The method includes the following cyclical steps: switching on a holding current to flow through the solenoid for holding the armature at the solenoid; after a predetermined period, switching off the holding current for causing the armature to begin a motion away from the solenoid; after switch-off of the holding current detecting, across the solenoid, a voltage change caused by the displacement of the armature for recognizing a starting moment of armature motion from the solenoid; and deriving a control signal from signals representing the voltage change ascertained in the course of the detecting step.

Abstract: A circuit breaker shunt trip accessory unit contains a solenoid driven plunger that interacts with the circuit breaker operating mechanism to interrupt circuit current by means of an external signal. A mechanical override feature insures operation of a blocked solenoid plunger once the source of the blocking is removed.

Abstract: An electromagnetic contactor to which voltage generated through full wave rectification of an alternating current or DC voltage is loaded. The device provides control for a closing operation with a large pulse width according to a set-up frequency and control for maintaining the closed state of the electromagnetic contactor with a small pulse width for executing ON/OFF control. The device comprises a detector for detecting a peak voltage value of the voltage subjected to full wave rectification and an average value or an effective value thereof and a controller for stabilizing the input at a constant level by controlling a pulse width of a frequency set up based on a voltage value detected by the detector.

Abstract: A solenoid device, for example in an electrical contactor system, is provided for use with an alternating current power source. An electrical contactor includes an electromagnetic coil assembly configured to generate a non-zero effective magnetic force in response to an alternating current signal applied across the coil assembly. A switch proximate the coil assembly is configured to operate responsively to the effective magnetic force. A wave shaping device is configured to introduce a direct current component to an alternating current signal provided by the alternating current power source and to output at least part of the alternating current signal modified by the direct current component across the coil assembly.

Abstract: A device for driving a load, in particular an electromagnetic load. The device includes a current detector for detecting the current flowing through the load, a power transistor connected in series to the load, which is triggered in dependence upon the current flowing through the load, and a further transistor arranged in parallel to the power transistor. The device has the advantage of reducing the power dissipation in the power transistor.

Abstract: A proportional valve has an output proportional to an electrical input signal. In a preferred embodiment, the valve is actuated by a proportional solenoid having a coil which is controlled by a control signal in proportion to voltage or current. The proportional solenoid is controlled by a relatively high current such as a rectified mains voltage. A control circuit ensures that the coil of the proportional solenoid is not overloaded. Particularly, it ensures that a maximum current value is not exceeded. In this way, the mains supply required in prior art devices may be eliminated.

Abstract: A remote closing operator is positioned within a circuit breaker enclosure to allow remote operation of the circuit breaker operating mechanism to close the circuit breaker contacts. A closing solenoid and associated logic circuit controls the state of the contact closing springs. The solenoid is energized to initially release the contact closing springs and is later prevented from operation upon any further attempt to release the contact closing springs after the contacts are closed.

Abstract: A solenoid driver circuit is provided that operates a solenoid in a quiet operation by reducing solenoid armature velocity. A pulse signal and a ramp signal are provided by a frequency generator and a ramp generator, respectively. A frequency switching circuit receives the pulse and ramp signals and responsively provides a time varying pulse signal that has a duty cycle that decreases with time. A dwell circuit allows the frequency switching circuit to control the solenoid for a first time period and then provides an on signal to the solenoid, maintaining the solenoid in the on position. The solenoid driver circuit is particularly suitable for use with solenoid controlled valves.

Abstract: A fuel injector control circuit is disclosed. The circuits can be used with a plurality of different fuel injectors and can be programmed to produce a plurality of different injector current waveforms. The control preferably includes a microprocessor with memory connected to a multiplexer and an application specific integrated circuit. The control can also be used to increase the current rise time of a specific injector current waveform.

Abstract: An internal combustion engine assembly including a solenoid pump having an armature and a solenoid winding encircling the armature such that the armature moves in response to current flow, including unwanted current variations, through the solenoid winding and a control circuit connected to the solenoid winding for detecting unwanted variable current flow in the solenoid winding and for controlling actual current flow in the solenoid winding in response to the detected unwanted variable current flow to thereby precisely control movement of the armature.

Abstract: A reduction in contact bounce in an electromagnetic switch is accomplished by optimizing armature speed over its travel path with a circuit arrangement for controlling a drive current in the coil of the electromagnetic switch. A superposed speed loop including a speed sensor produces a measured voltage in response to speed of the armature. A converter coupled to the speed sensor converts the measured voltage into a value corresponding to an actual speed of the armature. A first summer receives a constant reference value corresponding to a desired speed for the armature and the value corresponding to the actual speed of the armature, and produces a difference voltage corresponding to a difference between the desired speed and the actual speed of the armature. A proportional element amplifies the difference voltage and produces a desired current value corresponding to the amplified difference voltage.

Abstract: Electronic driving components sized to drive contactors of a determined power class are generally used. The object of the invention is to create a process and circuitry which allows contactors of different power classes to be driven by a single driving component. The user selects on a scale the switching position corresponding to the contactor to be driven. A reference voltage proportional to the magnitude of the starting current of the respective contactor is thus selected. An automatic regulation keeps constant the starting current during the starting time of the contactor. For that purpose, a measurement voltage proportional to the magnitude of the starting system and dropping across a measuring resistor is supplied to a first input of a comparator, a reference voltage which may be selected by a coding switch (6) being applied to the second input of the comparator. The output of the comparator co-operates with a switching element which switches the starting current.

Abstract: A method of detecting when a moving component of an electromagnetically operable device attains a final position after de-energizing a winding of the device comprises allowing the energizing current to fall to zero and prior to the component reaching its final position, connecting a sensing circuit in parallel with the winding, the current flow in the sensing circuit increasing from the instant of connections and decreasing when the component reaches its final position, said sensing circuit detecting the change in current flow.

Abstract: A varying voltage is applied across a coil of a contactor. The varying voltage has a characteristic (frequency) which varies as a function of the position of the armature. The varying voltage is transmitted to a coupler which transmits information to a controller. The coupler may include one or more light sources (LEDs) which are sequentially energized and de-energized to sequentially render a phototransistor conducting and nonconducting. The frequency of the output from the coupler corresponds to the frequency at which the phototransistor is changed between the conducting and nonconducting conditions. A controller determines whether the frequency of the output from the coupler corresponds to the intended position of the armature of the contactor or to an unintended position by comparing the frequency of the output from the coupler to known frequencies for various positions of the armature.

Abstract: The present invention provides a method and device for bringing the driven load of an internal combustion engine into motion by controlling the throttle or fuel delivery system of the engine and supplying a series of voltages to an electromagnetic clutch in a clutch engagement cycle. The throttle is set to a position or the fuel flow is regulated such that a specified torque output is produced by the engine. A detection means designates the time at which this output torque has been achieved. At this time, as designated by the detection means, a series of voltages is output to the clutch comprising a first voltage or voltage sequence to ensure engagement of the clutch, a second lower voltage to rapidly reduce holding torque to induce clutch plate slippage, a third voltage to maintain a desired rate of slippage, and a fourth voltage, preferably the rated voltage of the clutch, to lock the clutch plates together.

Abstract: This invention discloses a versatile power and control circuit for an electric door strike that is operable in four different modes with readily adjustable release times. In addition, the invention is directed toward the provision of a highly efficient power supply that permits miniaturization and prevents overheating in the confined space that is available for installation in a door jamb.

Abstract: This invention relates to a method and apparatus for recognizing the impact time of a solenoid valve armature during de-energizing. In order to obtain a detectable impact signal of the armature, a measuring current is provided in the magnet coil during the armature's downward movement to generate a magnetic measuring field. When this magnetic measuring field is changed due to the armature movement, an induction voltage is generated, which is monitored to detect the time of impact of the armature.

Abstract: A duty solenoid valve control apparatus and a duty solenoid valve control method, in which a plurality of duty solenoid valves different in operation from each other are controlled without increase of the program capacity of a computer. The apparatus comprises a duty signal generating device for generating a duty signal corresponding to a time ratio, an overexcitation signal generating device for generating an overexcitation signal to overexcite a solenoid coil, a holding signal generating device for generating a holding signal to hold a duty solenoid valve, and a signal synthesizing device for synthesizing the duty signal, the overexcitation signal and the holding signal into a drive signal for driving the solenoid coil.

Abstract: An overdrive circuit having a first current source which supplies an overdrive current and a second current source which supplies an ordinary current smaller than the overdrive current. A first circuit operates the first current source that supplies the overdrive current for a predetermined time period after the start of current supply. A second circuit stops the action of the first current source after the predetermined time period has passed and drives the second current source to supply the ordinary current as the driving current.

Abstract: A relay control circuit and method for closing a contact in response to an input signal received at a starting time. According to a preferred embodiment of the invention, a rapidly increasing electrical current is applied to the coil during an initial time period beginning at the starting time in response to the input signal, whereby a rapidly increasing force is applied to the contact to move the contact towards a closed position. The electrical current applied to the coil is decreased after the initial time period and maintained above a predetermined minimum magnitude until the contact is closed.

Abstract: Electronic drive circuitry for a solenoid that utilizes a pulse width modulation scheme is disclosed. The solenoid is connected in series with a transistor and a sense resistor. The voltage across the sense resistor is compared to a reference value to determine if an over-current condition exists within the solenoid. The circuitry operates on a repetitive time window scheme in which current is allowed to flow through the solenoid at the beginning of each time window, regardless of whether an over-current condition exists. If an over-current condition was detected at any time during the time window, then the current will be shut off to the solenoid during the next time window after the initial portion of that window. Conversely, if no over-current condition was detected during a time window, current will be allowed to flow during the entire duration of the next time window.

Abstract: A solenoid actuator for controlling the flow of fuel used by an engine is provided. The solenoid actuator includes a solenoid housing, timing circuit housing and a solenoid connector. The solenoid housing contains a pull coil and a hold coil. First side and second side pull coil conductors are electrically connected to a first side and a second side of the pull coil, respectively. Similarly, first side and second side hold coil conductors are electrically connected to a first side and second side of the hold coil. The first and second side, pull and hold coil conductors all exit from the solenoid housing. A timing circuit housing containing a timing circuit receives the first and second side, pull and hold coil conductors. The second side pull coil conductor is connected to the timing circuit. A ground conductor extends from the timing circuit housing and is electrically connected to the timing circuit and the second side hold coil conductor.

Abstract: A fuel injection valve drive control apparatus in which an opening current is supplied to an excitation coil to open an electromagnetic fuel injection valve, and thereafter a holding current is supplied to keeping the valve open, comprising a first switch connected in series with the coil, a valve driver for controlling conduction of the first switch, and a flywheel circuit and a second switch in parallel with the coil. The second switch is turned on a predetermined time following the start of supply of the holding current. A timer, provided to measure the predetermined time, starts clocking in response to the supply of the holding current or the valve opening current, or turning off of the first switch. The activation time of the second switch is shortened, whereby power consumption is reduced.

Abstract: A relay device (103) having a coil (144) and a set of contacts (146, 147) employs an apparatus (100) and method (200) for drawing current through the coil (144) to close, and maintain closure of, the set of contacts (146, 147). A first terminal of the coil (144) is coupled to a power supply (101) and a second terminal of the coil is coupled to a holding circuit (108, 115, 126) that establishes a first current through the coil (144). The second terminal of the coil (144) is also coupled to a closing circuit (112) that establishes a second current through the coil (144), wherein the first current and the second current together are at least sufficient to close the set of contacts (146, 147) and the first current is sufficient to maintain closure of the closed set of contacts (146, 147). A control circuit (118, 128) is coupled to the closing circuit (112) and the holding circuit (108, 115, 126) to remove the second current after the set contacts (146, 147) are closed.

Abstract: For dislodging of particulate material from precipitator plates, high voltage electrodes, hoppers, conveyance ductwork, etc., an electro-mechanical rapper module is removably combined with an electronic controller module in a single cylindrical unit that can be controlled and operated independently of any central controller. The rapper is preferably of the type that utilizes a spring-loaded hammer upstroke: being largely independent of gravity it can operate in any orientation. The controller drives the rapper in repetitive bursts at a rate of about 3 impacts per second, and provides selection of impact amplitude, on time and on delay. The unit can be controlled from a remote switch closure, and can be actuated manually by a pushbutton test switch on a control panel inside a top cover. The controller and rapper can be readily separated by removing a clamp, and can be operated as separate electrically-connected units.

Abstract: A photodetection system and related circuitry designed to sense the intrusion of an opaque object in a light plane. Upon sensing the intrusion, the system quickly initiates a machine-stopping sequence prior to the opaque object coming into contact with the machine while that machine is operating. The system comprises a SYSTEM microcontroller and a WATCHDOG microcontroller, both of which operate an output control device of the light curtain switch of the invention, wherein the output control device comprises a plurality of electromechanical relays. Both microcontrollers also perform system hardware and software integrity checks. Furthermore, the WATCHDOG microcontroller evaluates the performance of the SYSTEM microcontroller by transmitting a false intrusion signal to a photosource, determining whether the false signal has been detected, and then verifying that the SYSTEM microcontroller has initiated the machine-stopping sequence.

Abstract: A drive circuit of an electromagnetic contactor including a series circuit of a surge absorber and a diode connected in parallel with the coil of the contactor, and a transistor connected in parallel with the surge absorber. There are two operation modes. In a first operation mode, the contactor is opened immediately after the contactor has been closed by a starting pulse. In a second operation mode, the contactor is opened after the contactor has been closed by a starting pulse and held by holding pulses following the starting pulse. In the first operation mode, the transistor is kept in an on state for a delay time after starting the contactor. This prevents the current due to counter electromagnetic force of the coil from flowing through the surge absorber before the current is reduced below the allowable level of the surge absorber by the transistor. This makes it possible to protect the surge absorber from being overheated.

Abstract: A method for triggering a plurality of relay exciter coils connected parallel to a common voltage source includes turning each of the coils on and off with relay switching means associated with the coils, and triggering the respective coils to be turned on after reaching a response state thereof with a common clock generator having a given clock ratio, through the relay switching means, for establishing a steady state of a holding current being reduced relative to the response state. The method further includes turning off the coils with a common OFF-switch, keeping the respective relay switching means closed for those coils being intended to continue to be operated in the steady state of the holding current, for establishing a response current rising within a short time within the associated coil, and triggering the coil again with the clock generator having the given clock ratio after a predetermined period of time.

Abstract: A remotely controlled actuator assembly is provided to switch a large power distribution switch used in an electrical utility power grid. The actuator of the assembly throws the switch between at least two positions to establish at least two power routing conditions. The actuator assembly includes a position-sensing device to repeatably and accurately indicate the position of the actuator. The position-sensing device generates a signal indicative of the extent of displacement of the actuator. The generated signal provides feed-back to a control system which control the extent of actuator travel.

Abstract: An electromagnetic switch includes separable contacts, an electromagnet having a coil which is energized to close and hold closed the separable contacts, a power supply for applying current to the coil, and a closed-loop control circuit for sensing and regulating, throughout a contact closure cycle, the current applied to the coil to a selected current reference. The current reference may include a closing current reference for closing the contacts and a holding current reference for holding the contacts closed.