Showing papers on "Current sensor published in 1980"

System for sensing current in high voltage transmission lines utilizing the transmission of digital information by optical fibers

Abstract: A system and a method for sensing and reproducing a measured current value on a high voltage transmission line. An input shunt means (11) senses a current to be measured. A transmitter circuit transmits a sampled current value of the current passing through the shunt means. The transmitter has converter circuits (21, 22) for reproducing a composite output digital coded signal representative of the sample current value. A light transmitting output means (28, 29) is provided for transmission of the composite output digital coded signal on an optical fiber transmission line (12) to a receiver circuit. The receiver circuit has decoding circuit means for decoding and reconstituting the coded signal to a usable form to determine the sampled current value.

Current control system for an induction heating apparatus

Abstract: Coil current loading the induction coils of an induction heating apparatus is directly sensed at the input from the tank circuit and the derived feedback current signal is used to control the power supply to the tank circuit be reference to a signal provided manually or automatically under process control. A voltage feedback signal is derived with a transformer from the input to the tank circuit for providing an input to a voltage limiter operative on the current controller when the voltage to the tank circuit exceeds an acceptable limit. A current limiter overrides the current controller to limit the load current by control of the current controller when the load becomes excessive.

Power regulating apparatus including load current sensor means

Abstract: An a.c. regulator is disclosed including series and shunt choppers connected between a source of alternating current and an output, each chopper including a pair of unidirectional controlled rectifying paths connected in parallel opposition. The invention is characterized by the provision of a control circuit including a load current sensor for sensing the direction of flow of load current, the control being connected to render conductive a selected one of the transistors in the shunt chopper alternately with a selected one of the transistors in the series chopper, the alternation occurring at a frequency that is high relative to the supply voltage frequency.

Current mirror amplifiers with programmable gain

Abstract: A current mirror amplifier includes first and second transistors connected together at their common electrodes, the first transistor being connected for receiving input signal current at its output electrode, and the control electrodes of the transistors being connected for conditioning the second transistor for conducting a current responsive to the input signal current. Switch means, responsive to a control signal, selectively connects the output electrode of the second transistor to a supply terminal so the current gain between the input signal current and the current in the connection of their common electrodes switches responsive to the control signal.

Redundant sensor adapter

Abstract: An adapter for a multiwire security and surveillance system which permits the connection of redundant sensors at one location, without affecting the operation of non-redundant sensors at other locations. In one embodiment each of the redundant sensors is coupled to the adapter, such that individual sensor alarm currents are prevented from being applied to the signal wire. In response to simultaneously occuring latched output signals from the redundant sensors, a circuit within the adapter couples to the signal wire the same type alarm condition signal which is provided by the individual sensors. A voltage driver/current sensor circuit is interposed between an associated redundant sensor and the signal line to both sense an alarm condition at the corresponding redundant sensor and to isolate the sensor from the signal line, with the adapter coupling control signals through the associated voltage driver/current sensor circuit to the associated redundant sensor.

Mutual inductance current transducer for AC electric energy meters

Abstract: A mutual inductance current transducer includes a primary winding for direct connection to the current component of an electric energy quantity to be measured by an AC energy meter. A secondary winding is inductively coupled to the primary winding to produce an output signal that is proportional to the time derivative of the current component. The output circuit provides a current responsive input to an energy measuring circuit also receiving a voltage responsive input.

Speed control system for induction motor

Abstract: An error amplifier is connected to both a tachometer generator for an induction motor and a command speed generator to produce an error signal corresponding to the difference between the actual motor speed and a command motor speed. A current limit generator connected to the tachometer generator generates a current limit signal which is subtracted from a motor current signal from a current sensor for the motor. A multiplier imparts to the resulting difference signal the polarity opposite to that of the error signal as determined by a polarity discriminator. The difference signal is added to the error and actual speed signals by an adder to form a command frequency signal. An inverter controls the motor in response to the command frequency signal.

Dynamic current supply

Abstract: A dynamic current supply is connected between the emitter electrode of an output transistor and a point of reference potential, to progressively increase the magnitude of the flow of current therebetween, as the output signal at the emitter electrode approaches the point of reference potential. The dynamic current supply includes a current mirror, the output of which is in the path of and controls the flow of current. An MOS transistor, the conductivity of which is a function of the difference in potential between the operating voltage supplied to the output transistor and the output signal, supplies the input or control current to the current mirror.

AGC Current source

Abstract: A circuit for supplying a pair of currents that vary in opposite directions as a function of a control current. The pair of currents are coupled to an amplifying stage in which the gain varies in accordance with the relative magnitude of the currents. The circuit includes a differential current source having two output current terminals and a pair of controlled inputs. Both inputs are coupled to individual current sources. One input includes a resistor-diode current sink and the other input includes a current mirror sink. The control current is coupled to the current mirror thus varying the load on the related differential inputs. The current mirror input is also coupled to the diode current sink in the one differential input so that a delay can be introduced into the response to control current. That is, the control current must exceed a predetermined value before the gain reduction action occurs.

Current ramping controller circuit

Abstract: A circuit responsive to a supplied control input signal for alternately sourcing and sinking current at an output the values of which are accurately matched comprising a single current reference source and a single NPN current mirror circuit. The current reference source is unilaterally coupled to the output when the circuit is in a first mode of operation to provide the source current and is coupled to the NPN current mirror circuit which is rendered conductive in a second mode of operation to provide the input current to said current mirror. The output of the current mirror being coupled to the output sinks current thereat which is substantially equal to the input current supplied thereto. The NPN current mirrors comprises a pair of matched transistors having the bases and emitters interconnected at first and second nodes respectively. The collector of the first one of the matched transistors is coupled to the current reference source with the collector of the second transistor being coupled to the output of the circuit. A base current cancellation transistor is utilized to supply the base current drive to the two transistors.

Method for measuring leaking dc current from cable

Abstract: PURPOSE:To measure the leaking current simply and accurately by covering both ends of the cable by guard rings, connecting the guard ring and a conductor via a current sensor, and applying a DC voltage between the guard rings and a shield. CONSTITUTION:The guard rings A and B are provided so as to cover the tips of bushings 4 and 5 provided at both ends 2 and 3 of the cable to be measured 1 and shield rings 6 and 7. Said guard rings A and B are insulated against the conductor of the shield of the cable to be measured 1 and connecte to external DC high voltage current source 10 via a lead wire 15 and a high voltage branching wire 16. The guard ring B and the conductor 17 of the cable to be measured 1 are electrically connected at one end 3 via the current sensor 18. In this constitution, since the measuring preparation can be provided by only covering the preasembled guard rings on the tips of the cable ends, the leaking current of the cable can be measured simply and accurately.

Indicating device for use in airfield lighting plants technical field

Abstract: An indicating device for use in a plant for supplying electric current from an alternating current source to a loop circuit having a plurality of serially interconnected primary circuits of a number n of current transformers coupled to an airfield lighting lamp, comprises a transformer coupled to the alternating current source to generate a voltage signal representative of the voltage supplied to the loop circuit, a transformer coupled to the loop circuit to generate a current signal representative of the current flowing in the loop circuit, and an electronic circuit capable of generating in response to the voltage and current signals an output voltage indicative of the number of primary circuits of the loading transformers being uncoupled to their respective secondary circuits. The output voltage is proportional to the voltage integral. ##EQU1## of the loop supply voltage u from the time t o when the loop current i in each half period passes the zero value and to the time T when the loop current i attains a value corresponding to the saturation current i M for the current transformers. Preferably, a compensation voltage representative of the value of the voltage integral in case none of the current transformers has an unloaded secondary circuit is subtracted from the output voltage so as to obtain a final voltage signal which can be passed on to a meter precalibrated to indicate the number of uncoupled secondary units.

Electric drive or generator with permanent magnet rotor - has sensor for switching stator current conductors at correct relative position

Abstract: The drive or generator has a stator (2) incorporating at least sensor (38) which detects the relative position between the rotor (32) and the stator (2). The sensor (38) is coupled to a controlled electronic switching device which couples the stator current conductors (10) to the current source or current load when the correct relative position is attained. The sensor (38) may comprise a Hall probe, a reed contact, a photocell, an ultrasonic sensor, a gas flow sensor, an inductive sensor or a permeability sensor. The part of the rotor (32) to which it is responsive may be adjustable relative to the permanent magnet, or the sensor (38) may be adjustable relative to the stator (2).

Precision negative impedance circuit with calibration

Abstract: A negative impedance circuit comprising a level shifter and a current mirror, includes calibration circuitry for adjusting the negative impedance to provide the precise amount of current required to compensate for current drain caused by a known impedance at varying voltage levels. A divider/multiplier circuit is connected to the line which has the known impedance and provides a signal which is directly proportional to the voltage level on the line to the level shifter which, in turn, provides a corresponding control current to the current mirror. The current mirror provides a proportional current to the line current supplied by the current mirror and may be measured at a calibration resistor and the divider multiplier circuit may be adjusted to the appropriate ratio until the exact amount of current required to offset the drain to the precision resistor is provided by the current mirror.

Beam control circuit for diode-gun type camera tubes

Abstract: A beam control circuit which instantaneously increases beam current just sufficiently to discharge a highlight, utilizes the fact that a substantially linear relationship exists between the grid current and the available beam current of a diode-gun camera tube. A tube grid control circuit provides means for calibrating the relationship between the incoming signal current and the available beam current. A highlight enable circuit coupled to the grid control circuit is pre-biased whereby the beam current of the tube is maintained at a constant value as long as the video signal current remains within its normal operating range, i.e., there are no highlights in the viewed scene. However, when the video signal current increases above the pre-bias level, as in the presence of a highlight, the highlight enable circuit conducts to cause a corresponding increase in the beam current of the tube, wherein the beam current maintains a pre-calibrated, substantially constant margin above the video signal current which is just sufficient to discharge the highlight.

Procedure and means for monitoring current data in a thyristor-controlled direct current drive

Abstract: A method and apparatus for monitoring current data in a thyristor-controlled direct current drive, the drive system comprising two thyristor bridges converting alternating current into direct current for the drive motor and a current measuring unit. With the aid of a current controller the drive system is caused to operate in one of two different modes of operation, so that as the system approaches zero current condition, the normal mode of operation changes to an oscillating mode, the direct current circuit being monitored with the aid of a delayed current indicator datum in the zero current situation as well.

Broadband electromagnetic sensors for aircraft lightning research

Abstract: A set of electromagnetic sensors, or electrically-small antennas, is described. The sensors are designed for installation on an F-106 research aircraft for the measurement of electric and magnetic fields and currents during a lightning strike. The electric and magnetic field sensors mount on the aircraft skin. The current sensor mounts between the nose boom and the fuselage. The sensors are all on the order of 10 cm in size and should produce up to about 100 V for the estimated lightning fields. The basic designs are the same as those developed for nuclear electromagnetic pulse studies. The most important electrical parameters of the sensors are the sensitivity, or equivalent area, and the bandwidth (or rise time). Calibration of sensors with simple geometries is reliably accomplished by a geometric analysis; all the sensors discussed possess geometries for which the sensitivities have been calculated. For the calibration of sensors with more complex geometries and for general testing of all sensors, two transmission lines were constructed to transmit known pulsed fields and currents over the sensors.

Method for regulation and current limitation of a switched d.c. ringing-choke converter

Abstract: 1. Method for the regulation and current limitation of a direct current ringing choke converter by means of a pulse-width-controlled electronic switch (6), which is periodically ignitable under external control and extinguishable in dependence on a comparator signal, wherein a reference voltage (Uref) and an evaluation signal are compared for the formation of the comparator signal and wherein the evaluation signal is formed from the sum of a signal for the output magnitude to be regulated and a signal which is supplied by a current converter (10) which transforms the total current through the electronic switch, characterised thereby, that a unidirectional voltage value, which is proportional to the peak value of the total current through the electronic switch (6) and which is obtained by peak integration of the current converter output signal, serves as signal for the output magnitude to be regulated.

Field control device

Abstract: PURPOSE:To facilitate the control of field currents by sensing the field currents on the rotor side without contact by a photoelectric transducer. CONSTITUTION:A rotor 13 around which a field winding 12 is wound, a secondary winding 14 of a rotating transformer, a rotating rectifier 15, a field current sensor 16, and a photoelectric transducer 17 are installed to a motor shaft 11. When ac power is supplied to a primary winding 18 of the rotating transformer, the secondary induced voltage is generated in the secondary winding 14. The secondary induced voltage is rectified by the rotating rectifier 15, and the rotor 13 is excited by flowing the current through the field winding 12. The field current sensor 16 is connected to the output of the rotating rectifier 15 and senses the field current. The sensed signal is sent to the photoelectric transducer 17, generating the light whose amount corresponds to the field current. The transduced light is sensed by a light receiver 20 without contact, thereby the field current is controlled.

A high Precision Acoustic Current Sensor

Abstract: : This paper describes an acoustic differential travel time method of sensing fluid flow (e.g. ocean currents). For each axis of the sensor array a pair of acoustic transducers is simultaneously and repetitively connected to the same output of a crystal oscillator (typically 0.5 to 3mHz) to produce pairs of continuous wave bursts travelling in opposite directions. Before the acoustic signals arrive, each transducer is simultaneously connected to receiving circuits which then compare the phase of the arriving signals. The phase difference is directly proportional to the fluid flow velocity component parallel to a line joining the two transducers. Although this concept is not new, the method of processing the discontinuous received signals is novel and yields results which are essentially identical to truly continuous wave operation. The impossible problem of distinguishing simultaneously transmitted and received signals of the same frequency is avoided while superior zero ability and noise performance are achieved.

Welding spot detector and detecting method in automatic welding robot

Abstract: PURPOSE:To let the groove welding spots of a conceivable range be surely sensed by applying a detecting power source to he electrode of a torch, using this as a sensor and operating the welding spots from the position information of the work and torch. CONSTITUTION:A consumable electrode supply means 201 which supplies a consumable electrode 209 to a torch 116 is provided to a power supply unit 200. The specified voltage is applied by a voltage-applying means 203 to the consumable electrode 209 being let off. A high voltage power source 206 for discharging is connected to the work W by way of a current sensor 207 which detects the current change with discharging between the electrode 209 and work W and applies a signal to a control box 400. The control box 400 changes over a changeover switch 204 to 205 of the welding power supply at the welding and changes over to a discharge power supply 206 at the sensing. Further, the control box 400 moves and slews a fixture 115 by programs and controls the relative positions of the work W and torch 116.

Compensating device for load transfer of axle

Abstract: PURPOSE:To compensate axle loads properly and to prevent the occurrence of slip and skid by controlling the field system of the motor of an axle whose axle load has become heavy by additive excitation. CONSTITUTION:The input sides of rectifiers 6 to 9 with control gates for additive excitation are connected to an ac power supply and the output sides thereof are connected to field coils 1F to 4F of motors 1 to 4 in parallel. A current sensor 11 is used for sensing motor currents, and the output of the sensor 11 is received by a pattern generator 12. When the motor current approaches the limit of occurrence of slip or skid, are generated gate control voltage to be applied to the rectifiers 6 to 9 with the control gates for additive excitation in order to change the field currents of individual axle mortors independently. The point at which additive excitation is started is set at the level adjacent to the occurrence limit of slip of the axle which has the lightest load. In this constitution, occurrence of slip and skid can be prevented without decreasing an electric braking force.

Current comparator circuit

Abstract: A current comparator circuit is composed of an input signal current source, plural pairs each consisting of a diode and reference current source, and plural switching elements. The pairs each consisting of a diode and reference current source are connected in series or in parallel to the input signal current source. Each switching element is a transistor, which is connected to the connection point between the paired diode and reference current source, and a compared output can be obtained from the collector of the transistor.

Control circuit for battery-powered electric lawn-mower - includes series motor current sensor to control voltage for constant speed despite various loading

Abstract: The control circuit for a battery driven electric lawn mower maintains constant speed of rotation for different load conditions. Between the battery (11) and the motor (12) is an electronic control circuit (13) with an inductive coil (14) and diode (21) in series with them, and a load capacitor (15) is parallel with the motor. Also in parallel is a switching device (16) which can be a mechanical switch or a switching transistor. A current-to-voltage converter (17) between the motor and the diode responds to changes in the motor current and operates through an equaliser (18), a control amplifier (19) and a pulse width modulator (20) to regulate the voltage and hence the motor speed.

Control device for double static converter - has zero current signalling device with variable switching threshold depending on current actual value

Abstract: The convertor is free from circulating currents and has a polarity reverser followed by a current controller and reversing logic circuit. A current direction signal derived from the required current, and a zero current signal derived from the actual current value are applied to its inputs. Its outputs control the polarity reverser and a pulse invertor between the control pulse set and double static convertor. In order to obtain the zero current signal in transformers in the connections to the static convertor, a full-wave rectifier with a DC load, followed by a zero current signalling device are provided. A zero current signalling device has a variable switching threshold depending on the current actual value and varying with it.

Dc brake controller for induction motor

Abstract: PURPOSE:To restrict the speed reduction of an induction motor by limiting the braking torque to a specified value by making feedback control of a differentiated quantity of a speed in the case where the excessive torque is generated at the time of low speed of dc braking torque. CONSTITUTION:The rotation speed of an induction motor 1 is sensed by a speed sensor 10 and differentiated by differentiating circuit 11 and a decceleration (acceleration) torque signal is obtained. Difference between this signal and the maximum value of the DC braking torque of a torque designator 12 is amplified by a torque control amplifier 13 and a current-reference signal is obtained. The current-refernce signal and the output signal of a current sensor 4 are input to a current control amplifier 6 together, and the amplified difference signal is supplied to a power converter 2 through a phase controller 7 to control a DC brake current. The maximum value of the motor current is controlled by a limiter 14 which determines the upper limit of the current reference value. In this constitution, the braking action is applied at the maximum allowable current in the high-speed region, and speed reduction is restricted by the torque designator in the low-speed region.

Vibration generator for an ultrasonic liquid atomiser

Abstract: The vibrator is a circuit arrangement which is to even at low operating voltages oscillate safe, he should tune only slightly under load and to make do with just a few active and passive elements, whereby this is excited exclusively on the Zerstauberresonanz and-or battery. is all battery suitable. It consists of a push-pull amplifier (21, 22, 29, 30, 31) containing oscillator circuit with an inductive positive feedback 23, 27) and a piezoceramic diffuser element (25), in the power supply, a selective current sensor (27,28) is located, the amplifier to controls in mitkoppelnder way and stimulates to vibrations that occur after adjustment exclusively on the Zerstauberresonanz the piezoceramic oscillator.

Diagnosis apparatus for automobile

Abstract: PURPOSE:To accomplish independent measurement at particular points while facilitating item-wise selection by processing the results of measurement, while selecting diagnosing items with the turning-on of a switch provided for the detector. CONSTITUTION:A voltage measurement starting switch 4 having a voltage sensor 3 and a current measurement starting switch 6 adapted to measure the current value with a contactless current sensor 5 are connected to an automobile diagnosis apparatus equipped with a display 2. With the operation of a measuring object switching multiplexer, the voltage sensor 3 is connected to one input terminal and likewise, while the current sensor 5 done to the other input terminal. The output terminal of the multiplexer 8 is connected to the resistance 9 of a gain change-over device which is connected to a data processing device 17 by way of gain change- over resistances 10-13 and a multiplexer 14 and via an operation amplifier 15. When the switch 4 is turned on, the signal is applied to the device 17 for measurement of voltage. In addition, a sensor 5 can be detect the current converted into the voltage.