Abstract: A circuit arrangement for limiting the current to be switched of an electrical load, with the power input of the electrical load being controlled by means of a Triac, said Triac being connected in series with the electrical load, with a Diac being connected to the gate terminal of the Triac, said Diac being connected in series with a resistor arrangement whose resistance value is variable for the purpose of controlling the Triac, said Triac being disconnectible from the power supply by means of a first switch, wherein a second switch is provided by means of which the series arrangement comprised of the resistor arrangement and the Diac is disconnectible from the power supply, and wherein, on turning the electrical load on, the first switch is closed first, while the second switch is closed with a time delay. Advantageously, on turning the electrical load off, the second switch is opened first, while opening of the first switch occurs with a time delay.

Abstract: A low voltage power control circuit supplies substantially equal voltages to a plurality of loads distributed along a pair of parallel wires. Moreover, the voltage delivered is automatically controlled by a feedback control circuit, so that the number of loads in the system may be varied without causing a substantial change in overall supply voltage supplied to the plurality of loads.

Abstract: A motor control arrangement including a control circuit for controlling the speed of an electric motor (EM), which control circuit comprises a measurement resistor (MR) and a switching transistor (ST) having a control electrode and a main current path coupled in series with the electric motor (EM) and the measurement resistor (MR), a pulse width control stage (PW) coupled to the control electrode of the switching transistor (ST), a motor current measurement stage (MI) for controlling the pulse width control stage (PW) in response to a motor current of the electric motor (EM), and a motor voltage measurement stage (MV) for controlling the pulse width control stage (PW) in response to a motor voltage (EM) of the electric motor (EM).

Abstract: The invention relates to a device for controlling the variation of the power and/or the speed of a load (2), such as an asynchronous, synchronous, universal motor, a transformer, an inductance, a condenser or a resistor, comprising a switch (5) placed on a phase (4) of a single-phase or multiphase alternating-current supply-circuit (3), this switch (5) being associated with means (6) for controlling the cyclic ratio .alpha./T in which .alpha. corresponds to the time of opening and closing of the circuit (3) by the switch (5) and T to the period of the phase (4) on which this latter is placed. In fact, the switch (5) is of the bidirectional MOS, IGBT or bipolar transistor switch type, this switch (5) being associated with means (9) for controlling the switching time, of the DRIVER type, capable of extending the switching time at closing so that it be within a range from 10 microseconds to 1 millisecond.

Abstract: A dimmer for use in lighting control in which a triac control circuit in included which allows for control of both incandescent and low voltage lighting systems at low and high intensities 142,144. The triac control circuit includes a microcontroller 130 which alters the duration of the gate triggering pulse for the triac 134 based upon the desired intensity level of the load. This dimmer is used in a lighting control system and the dimmer is responsive to a system controller 2 as well as to momentary switch inputs which are made directly to the dimmer. The triac control circuit can also be used with other inductive loads.

Abstract: Power saving circuitry is provided for use with fluorescent lights, inductive loads and resistive loads. The circuitry comprises a power circuit connectable to an alternating circuit power supply and a control circuit. The power circuit includes a bilateral switch, and the control circuit includes means for timing the operation of the bilateral switch so that the switch conducts current for a predetermined time during each half-cycle of the power supply which terminates at a predetermined interval before the end of each half cycle. A preferred embodiment of the power saving circuitry, adapted for use with fluorescent lights or inductive loads such as electrical motors, also comprises a Back-EMF suppressor circuit. The bilateral switches are preferably made up of one or more unilateral switch devices such as field effect transistors. The subject circuitry reduces power consumption while at the same time providing for a power factor correction.

Abstract: Procedure and apparatus for the control of electric power, by which procedure the electric power supplied to a load is regulated by means of a regulator, e.g. a thyristor regulator. The regulator control signals, e.g. thyristor firing pulses, are produced by a separate control unit (6), from where they are passed in the form of optical signals via at least one optical fibre (2) to a socket or equivalent and further to a photosensitive device (Q), which converts the signals into electrical form and applies them to at least one controllable solid-state component, e.g. thyristor, in the power stage of the regulator.

Abstract: A method for regulating the power in a load connected to the mains through a controlled switch and a device for implementing the method. The method includes the following steps: detecting a mains synchronization pulse, which determines the start of a cycle, within a fixed time interval of the preceding cycle; as soon as the pulse has been detected, waiting for the end of the fixed interval, then counting down a first time interval that substantially corresponds to a selected time interval; at the end of the first time interval, triggering the switch on and counting down a second time interval that ends before the normal arrival of the next synchronization pulse; and at the end of the second time interval, counting down the fixed time interval within which the next synchronization pulse must be detected.

Abstract: An electric bulb saver is provided for use with light bulb sockets in either 110 V or 220 V screw type or bayonet circuits. The device includes circuitry comprising a resistor, a capacitor and a rectifier. The circuitry may also include in specified combinations, thermistors, a bridge rectifier, as well as additional resistors, capacitors, and rectifiers. The circuit may be housed in a socket, wall switch or plug, in an on-line connection, or in a device attached to the socket.

Abstract: An apparatus and method for controlling the voltage applied to a load is taught. The method includes receiving an AC line voltage, generating an operating AC voltage from the AC line voltage and applying this operating AC voltage across the load. A measured signal which is a function of the magnitude of the operating AC voltage is generated, and then averaged to generate an average signal representative of the average value of the measured signal. The operating AC voltage is continually readjusted in response to changes in the average signal. The apparatus implementing this method includes terminal means for receiving an AC line voltage, means for generating an operating AC voltage from the AC line voltage, connector means for applying the operating AC voltage across the load, and voltage detection means for generating a measured signal which is a function of the magnitude of said operating AC voltage.

Abstract: An ozonator power supply including a step-up transformer having one end of its primary winding connected to one side of an AC supply, its other end connected to the other side of the AC supply via a pair of switches connected in antiparallel, and a controller for providing switching pulses to said switches for making them conductive during variable portions of alternate half cycles of the AC voltage provided by said supply. An inductor is included in the circuit with the primary or secondary winding of the transformer that resonates with the capacitive impedance of an ozonator, for presenting a substantially non-reactive load to said AC supply.

Abstract: An improved phase-controlled power control apparatus includes a semiconductor switching element for varying the effective power delivered to a load from the power lines. The conduction angle of the semiconductor power switch element is varied from a nominal angle to compensate for changes in power line voltage and for changes in load current. The amount of load current flow is continuously compared to the power line voltage to detect any overcurrent condition, even very close to the zero-crossing of the power line voltage. The shape of the transition from load current on to load current off (or vice versa) in controlled to minimize audible noise from the load. The load current can be shared between a plurality of compatible power control sections.

Abstract: A lamp control module including a housing having a receptacle therein with a transformer winding wound around the inner walls of the receptacle in being operatively driven by a programmed microprocessor. The transformer winding of the module is further operative to be inductively coupled to a second transformer winding which is located within an on-off switch knob of a wall switch panel, and the second transformer winding is further connected to the gate electrode of an AC switch. Pulses which are generated in the lamp control module and controlled by data values stored in the microprocessor therein are transformer coupled from the housing receptacle transformer winding into the knob switch transformer and then to the gate electrode of the AC switch. These pulses are operative to control the phase angle and conduction time of the Triac and in turn control the conduction time that an AC voltage is applied from an external AC voltage source to a lamp.

Abstract: An electronic controller (22) designed to be placed within an electrical series circuit for the purpose of controlling voltage and amperage applied to a series load (21) within the same circuit. The concept of design being that the controller is attached exclusively to the series circuit and obtains operating voltage through the points of connection to the series circuit. The controller provides a wide range of variable amperage control to the load being driven. Further design features are that the controller operates within a series circuits comprising alternating current, rectified alternating current, pure direct current or a combination of any without modification.

Abstract: A phase-controlled power modulation system switches modes in response to circuit-threatening conditions to avert the necessity of a shutdown. Normal operation is in reverse phase control (RPC) mode. When an inductive load sensor detects the presence an inductive load, the system switches to a forward phase control (FPC) mode (FPC) to minimize voltage spikes that would otherwise result from the load's opposition to voltage transitions. When an overcurrent sensor detects an overcurrent, the system switches into an asymmetric hybrid mode (AHPC) to maximize delivered power while remaining within switch current handling capacity. In AHPC mode, an RPC component of a half-cycle waveform is cut off at the current limit, while an FPC component of the same half-cycle waveform is triggered after the source voltage drops to a confidence threshold below the current limit to ensure that current limiting is not triggered again during the same half-cycle.

Abstract: A system to control power from a source to a load consists of a cover plate, a touch-operable device that is mounted behind a flexible area on the cover plate, and a power control circuit that responds in accordance with a signal generated by the touch-operable device. The system is operated by touching a point within the flexible area of the cover plate to activate the device. In a preferred embodiment, the system provides power over a continuous range of values, depending on the particular point at which the device is activated. Alternatively, the system operates as a switch, alternately turning power on or off when any point on the flexible area is touched. The control circuit preferably includes an electronically adjustable voltage divider. The system is well-adapted to permit control of power to a load from multiple locations. The appearance of the front surface of the cover plate can be dictated entirely by aesthetic considerations and can, if desired, be entirely featureless.

Abstract: An apparatus for stepless control of electric loads by the phase-angle principle includes a semiconductor switch element with main electrodes. A trigger circuit furnishes turn-on pulses for triggering the switch element and includes a detector for the polarity of an instantaneous value of an alternating voltage to be switched, a turn-on pulse pregenerator circuit for furnishing turn-on pulse suggestions, a switch and driver unit, and a decision stage. The decision stage may allow or prevent the turn-on pulse suggestions to be switched through to the switch element, as a function of whether an output signal of the detector has changed its polarity between two of the turn-on pulse suggestions.

Abstract: An apparatus for stepless control of electric loads by the phase angle principle includes a semiconductor switch element. A trigger circuit is connected to the semiconductor switch element for furnishing turn-on pulses for triggering the semiconductor switch element. The trigger circuit includes at least one current flow detector, a turn-on pulse pregenerator circuit, a switch and driver unit, and a time-dependent circuit element. The on-state angle of each current half-wave is compared with a maximum allowable limit value of the on-state angle through the use of the current flow detector and the time-dependent circuit element, and a further triggering of the semiconductor switch element is prevented if the maximum allowable limit value of the on-state angle is exceeded. An apparatus for controlling the brightness of an incandescent bulb includes a transformer having a primary winding with two terminals and a secondary winding connected to an incandescent bulb.

Abstract: The invention pertains to electrical power control more particularly to a class of circuitry known as thyristor phase control. The novel circuit can be used to control heating devices, electrical motors and generators and many other types of equipment that require a precise control of the output of a thyristor.

Abstract: An electric power consuming system such as the lighting in a building has local control units for adjusting the power consumed by a preselected load or loads associated with each local control unit. The control units generate a selectable control voltage which has a first range specifying to the loads that no power should be consumed by the loads with voltage outside the first range specifying by its level the amount of power which the loads should draw. The system also includes energy management apparatus whose output is connected across the output of the control units and which can limit the power individual control units can specify to their loads. The invention comprises an interface circuit which connects the energy management apparatus to the control units and translates control voltages from the energy management apparatus falling within a second voltage range within the first range of the selectable control voltage, to a voltage falling outside the first voltage range.

Abstract: AC power loads such as from transformers, motors, high in-rush heaters, air conditioners, etc., are controlled by the use of bipolar transistors, FET transistors, gate turn-off SCRs and IGBT to turn on the load at zero-cross over and to turn off the load at any point in the sine wave which produces the desired amount of power. This reduces RFI and virtually eliminates di/dt at turn on since both voltage and current start at the same zero cross-over, and hence will improve the power factor. Both analogue and digital logic systems can also be utilized to produce this type of phase control, and a wide variety of possibilities are available such as serial and parallel input, the use of full wave bridge control, etc.

Abstract: A method and circuit for reverse phase control of alternating current being delivered to a load are disclosed wherein voltage-controlled semiconductor switches, such as MOSFET's and IGBT's, are used as electronic switches to conduct voltage during the leading edge of the AC voltage cycle and conduction is terminated when the desired phase angle of the current flow has been reached. The disclosed method and circuit eliminate the need for zero crossing detection of the AC waveform and ensure that the voltage-controlled switches are always turned on before the zero crossing thereby minimizing radiated interference and incandescent lamp hum. The method used is primarily digital in nature making mechanical input or electronic input for the power control equally efficient to implement.

Abstract: A load power control circuit which adjusts the level of power provided by a load in response to changes in the impedance across control terminals includes a control circuit which disconnects the load from the power source when the voltage across the control terminals in within a certain range. The control circuit is particularly useful in controlling fluorescent light fixtures controlled by electronic ballasts because the control circuit avoids the need for a separate on/off switch for the fixtures.

Abstract: A two-wire apparatus for controlling AC power to a load, by turning a thyristor on and off during each half cycle, includes a circuit that prevents the thyristor from being turned off prematurely. The circuit stores energy while the thyristor is off (i.e., non-conductive). After the thyristor turns on, the stored energy flows to the gate of the thyristor to keep it on until the end of the half cycle. The circuit permits reduced electromagnetic interference and increased load power rating; without requiring a third (neutral) wire for the apparatus.

Abstract: A phase switched power controller connects a load to a alternating current source for a proportion of each half cycle selected by the user. A first full wave rectifier is connected to the voltage source and produces an unfiltered full wave rectified output signal varying between zero and a predetermined peak. A low pass filtered full wave rectified signal is preferably obtained from a second full wave rectifier, the filtered voltage and unfiltered voltage being applied as inputs to a voltage comparator, the output of which triggers a timer. The timer determines the phase delay until a further pulse is triggered for activating a triac, applying power to the load during the remainder of each half cycle.

Abstract: A control circuit for generating gating signals to drive the SCRs of an AC switch coupled between a three phase AC source and a three phase load. A reference voltage signal is derived from the source and, after filtering, is applied to a squaring amplifier. The amplifier output is applied to a phase-locked loop (PLL). The output signal of the voltage controlled oscillator (VCO) of the PLL is fed back to the phase comparator thereof via two dividing counters. The output of one counter is applied to a logic block for generating a ramp reset signal in phase with a selected source phase-to-neutral voltage. The ramp reset signal is applied to a ramp forming circuit the output of which is applied to a first input of a comparator. The comparator receives a DC control voltage on its second input and provides on its output a gating signal corresponding to the source selected phase.

Abstract: A current switch which emulates a thyristor by using enhancement mode field effect transistors. A center tapped current transformer and a push-pull field effect transistor arrangement eliminates the need for either rectifier diodes or a full wave bridge connected to the current transformer.

Abstract: A position-sensing circuit includes an elongated electrically-conductive element divided into two elongated segments. A conductor moves along the element, maintaining electrical contact with at least one of the segments. A first capacitor is connected to the conductor and a second capacitor is connected to one of the segments. When the conductor bridges a gap between the segments, a step-wise change in the time constant of the circuit results. This step-wise change precisely and reproducibly indicates the position of the conductor as being across the gap. The circuit finds particular advantage in a three-way dimming system that permits a remote switch to provide power to a load even if a dimmer that controls the load has been set to provide minimum or no power to the load.

Abstract: A power controller having first and second power outlets, connections between one side of an A.C. line to one side of each outlet, a current sensing impedance connected between the other side of the A.C. line and the other side of the first power outlet, a triac connected between the other side of the A.C. line and the other side of the second power outlet, a first operational amplifier normally maintaining the triac in a non-conductive condition and a second operational amplifier to cause current to flow through the triac to the second power outlet after a selected time delay whenever an appliance such as a power tool that is coupled to the first power outlet draws a given amount of current through the sensing impedance.

Abstract: A solid state power controller off-line capacitor divider power supply coupler between an ac voltage source output terminal and neutral terminal, supplying regulated dc voltage levels referenced to the ac voltage source output terminal to a load such as the control and drive circuits of a solid state power controller. The invention circuit comprises an input capacitor having a first and second terminal. The capacitor first terminal is coupled to the ac voltage source neutral terminal. A first diode has an anode and a cathode; the anode is coupled to the capacitor second terminal. A positive filter capacitor has a first and second terminal. The first terminal being coupled to the first diode cathode and the filter capacitor second terminal being coupled to the control and drive circuit reference terminal. The invention circuit has a first positive regulator means with an input terminal, an output terminal and a reference terminal. The input terminal is coupled to the filter capacitor first terminal.

Abstract: The power delivered from a three-phase A-C power source and through a network of SCR's (connected, for example, to form a full wave rectifier bridge or to provide an A-C switch) to a load circuit is adjusted by controlling the conduction angles of the SCR's. The control is achieved by developing, from only one of the three alternating phase voltages provided by the A-C power supply, a reference square wave signal of the same frequency and whose amplitude excursions are precisely synchronized or keyed to the zero voltage crossings of the selected phase voltage, even though that phase voltage may include undesired harmonics, noise, transients or other distortion components.

Abstract: A method and apparatus for providing a pulse-generating control to energize the electrodes of an electrostatic precipitator which includes means for producing a voltage between the electrodes of the precipitator after a voltage pulse has been applied to the precipitator electrodes which is higher than the voltage existing between the electrodes prior to the application of the voltage pulse and which voltage pulses are repeated until a preselected voltage is achieved between the electrodes.

Abstract: An alternating current power controller is provided that employs DC transistor switching for subcycle switching capability and to eliminate problems associated with SCRs and furthermore provides internal elements for generating the required DC control power from the AC source whether the AC load is on or off.

Abstract: An improved zero voltage switching AC relay circuit is disclosed which includes two photo sensitive silicon controlled rectifiers (photo-SCRs) connected in inverse parallel as the active switching elements. The photo-SCRs are triggered into conduction by a light source including two light emitting diodes. Zero voltage switching circuitry is also provided which prevents the photo-SCRs from being triggered into conduction by the light source except when the value of the AC voltage being controlled is within a predetermined limit of zero volts. This is accomplished by using the collector-emitter circuit of a transistor to shunt the gate-cathode circuit of each photo-SCR. A transistor is provided for each photo-SCR, and the bases of the transistor are connected to each other by a single current limiting resistor.

Abstract: A circuit for energizing a gaseous discharge lamp at high frequency utilizing a thyristor, preferably an SCR. The energizing circuit for the lamp includes a resonant or tank circuit operating at an appropriate high frequency, preferably above the acoustic resonant frequencies of the lamp, and which also commutates an SCR. The cathode/anode of the SCR is connected to a voltage adjusting network to provide an initiating pulse through the SCR to start oscillations in the resonant or tank circuit when the SCR is gated on and which reduces the applied supply potential to the SCR during its conduction period to ensure non-conductive latching of the SCR when the gate thereto is removed by lengthening the natural commutation interval of the SCR. This permits the SCR to be used as a switch at the high frequencies involved, normally about 60 kHz.

Abstract: An improved precipitator voltage control system including an automatic voltage control (AVC) circuit, a firing circuit, an alarm circuit, a power-saving circuit, a remote set-point control circuit and a power supply, all of which are mounted on a single, readily interchangeable circuit board. The automatic voltage control circuit includes a highly responsive spark detection subcircuit which causes the transformer/rectifier voltage to be reduced to zero at the end of the half-cycle in which a spark occurs and then causes the voltage to remain at zero for a short period of time after which voltage is reapplied in a dual ramp manner causing it to rapidly reach a level below the precipitator arcing potential and then increase at a slower rate to the threshold of sparking. The firing circuit drives silicon-controlled rectifiers (SCRs) through optical couplers which provide several thousand volts of circuit isolation.

Abstract: An interface circuit is provided for interconnecting an electronic controller to a contactor circuit which, in turn, controls the alternating current flow from an alternating current power source to controlled equipment, such as a resistance welding machine. The contactor circuit, for example, includes a pair of semiconductor switching devices, such as silicon controlled rectifiers (SCR)s, the two semiconductor switching devices are alternately rendered conductive during successive half-cycles of the alternating current power from the alternating current power source at times controlled by the controller for the controlled operation of the welding machine. The interface circuit includes means for monitoring the junction temperature of each of the semiconductor switching devices, and to provide an indication and a control effect should the junction temperature exceed a particular safe threshold.