Showing papers on "Relay published in 1984"

Circuit breaker and protective relay unit

Abstract: Circuit protection and protective relay functions are provided by common circuit elements under the control of a single processor unit. Voltage and current values are obtained on a continuous basis and these values are continuously monitored within the processor to determine the electrical status of a protected power distribution system. Upon the occurrence of an overcurrent or undervoltage condition, the circuit is interrupted by operation of a circuit breaker trip solenoid causing the breaker contacts to open. When the overcurrent or undervoltage condition ceases to exist, the circuit breaker contacts could be closed by operation of a controlled relay. The ROM and RAM storage elements within the processor unit are continuously tested and the circuit breaker contacts are opened upon indication that the ROM or RAM element is nonfunctional.

Computer Aided Transmission Protection System Design Part I: Alcorithms

Abstract: The role of a computer-aided-design tool in assisting protection engineers is defined. In the process, we identify three computational problems for which algorithms are not readily available: network analysis to find primary/backup relay pairs, setting directional overcurrent relays and setting distance relays. Suitable algorithms for each of these tasks are presented.

Power steering device

Abstract: PURPOSE:To improve the sense of steering during high speed running by generating auxiliary steering power when the steering power exceeds the first set point and car speed is below a specified one and generating the auxiliary steering power independently of the car speed when the steering power exceeds the second higher set point CONSTITUTION:When steering power exceeds the first set point and is below the second set point during steering, a steering power sensor 22 issues an output signal to the contact 21 of a relay 19 At this time, if the car speed is below a specified value, a car speed sensor 18 issues a low speed signal Thus, a solenoid 20 is excited and the contact 21 is closed As a result, since the solenoid 24 of a relay 23 is excited and a contact 26 is closed, a motor 10 is started If the car speed exceeds the specified value, since the sensor 18 will not issue the signal, the contact 21 is opened and the motor will not be started If the steering power exceeds the second set point, the sensor 22 directly issues the output signal to the solenoid 24 without interposing the contact 21 and the contact 26 is closed Consequently, the motor 10 is started in this case independently of the car speed

Electromagnet access control circuit

Abstract: An electromagnetic lock for doors includes a large electromagnet mounted on the door frame, and a strike plate or armature secured to the door. A double-throw, double-pole type of relay or other switching circuit serves to selectively connect the electromagnet to receive rectified current when it is energized, and to receive a reverse pulse from a large capacitor when the door circuitry is de-energized. The large capacitor is charged to the same voltage as the electromagnet to insure full reversal of the magnetic domains to prevent residual magnetism. The double-throw, double-pole switch may be actuated by a high speed relay to insure timely switching of the contacts to apply reverse current from the capacitor to the electromagnet. The relay coil may be a latching relay which is selectively actuated in one direction while the circuit is energized, and is reversed as the electromagnet is discharged, so that it draws no current except when it is being switched on. A diode is provided to prevent oscillation of the circuit including the electromagnet and the large capacitor, as well as to block inductive kickback.

Electronic security system for externally powered devices

Abstract: An electronic security system for a device requiring an external power source is disclosed. The security system includes a microcomputer which executes a power-on routine stored in memory whenever the microcomputer is initially coupled to a power source. The user must enter a primary security code which is compared to a predetermined code, and if the codes match, the microcomputer signals a relay to provide power to the device, thereby enabling it. Once enabled, the user need not reenter the security code as long as the external source of power to the device remains uninterrupted. A secondary security code may be entered if the primary code has been forgotten or misplaced. Upon entry of the secondary code, the microcomputer displays an encrypted version of the primary security code. If an incorrect code is entered by the user, the microprocessor executes an alarm routine which may include visual and audible warnings.

PPM Performance for Reed-Solomon Decoding Over an Optical-RF Relay Link

Abstract: Consideration is presently being given to an optical-RF relay deep space communication link that transmits optical PPM data from spacecraft to orbital relay, then retransmits the data via microwave to ground. It is generally advantageous to use Reed-Solomon (RS) encoding over the PPM optical link for improved error correction. In this paper several demodulating schemes are considered for generating the RS symbols at the relay photodetector output, and the effect of each on overall RS decoding performance is computed. Both Poisson and Gaussian optical noise models are used in the evaluation. The effect on performance of bit errors in the relay downlink is also examined.

Facsimile communication relay system

Abstract: A facsimile communication relay system includes a relay station which temporarily stores image information to be transmitted from a source station to a destination station, for example, at a desired time. In accordance with the present invention, address and image information once transmitted and thus temporarily stored in the relay station is returned to the source station thereby allowing an operator at the source station to check the condition of the information received at the relay station, and the image information stored at the relay station is made available for transmission to the destination station only if an enable transmission signal is transmitted from the source station to the relay station by the operator within a predetermined time period.

Method of using data from computer simulations to test protection equipment

Abstract: The paper describes a computer-aided protection evaluation equipment which has been developed primarily to investigate protective relay performance during the period immediately following fault inception. Modern mathematical techniques allow the transient behaviour of a power system to be determined and the equipment described permits this calculated information to be used to evaluate relay performance. The equipment comprises two main elements—a simulation executed on a computer and a means of using the simulation to test protective relays. Novel techniques are described for removing sampling effects from the analogue signals, for small signal modelling of transducers and for the evaluation of unit protection schemes by the simultaneous application of currents and voltages from two points on a power system. Both the hardware and operating software are detailed and information is given concerning the computer simulation of the power system.

Device for regulating ac current circuit

Abstract: The present invention provides a device for regulating an ac current circuit using a magnetic relay which is suitable for use in an incandescent lamp circuit or electric motor circuit to eliminate or reduce inrush-current. The present device comprises connecting power switch, diodes, series resistance and relay such that, after closing the power switch, an ac current first flows to a load through the series resistance for a brief time, then to the load through the contacts of the relay after a lapse of the brief time by bypassing the series resistance.

Photovoltaic relay switch

Abstract: A photovoltaic relay which includes a unique pull down circuit for rapidly turning off the relays field effect transistor(s). The pull down circuit discharges the gate-to-source capacitance of the relay's field effect transistors by turning on a thyristor by turning off a light-activated switch connected between the gate and the cathode terminals of the thyristor. In one integrated circuit embodiment, the light-activated switch is energized by the same light source which activates the photodiode stack which drives the relay. The presence of the pull down circuit does not effect the turn on time of the relay.

Facsimile relay device

Abstract: A facsimile relay device includes a battery backed-up memory for storing an image information sent from a sending station and information concerning the latter station and a control means for sending to the sending station a relay certificate notifying of a completion of a relay of the image information to a destination station. The control means operates to repeat the sending of the relay certificate when the sending is unsuccessful and to print it out after a predetermined number of repetitive sendings of the certificate.

Diagnostic testing arrangement for an electric cooking appliance incorporating commutated relay switching circuits

Abstract: A power control and diagnostic arrangement illustratively embodied in an electric range having multiple surface heating units which are selectively coupled to an AC power supply by commutated relay switching circuitry The commutated relay switching circuitry includes two switching networks Each network includes a diode commutated master relay serially connected to a pair of pilot relays Each pilot relay is serially connected to one of the surface units Timing and control circuitry periodically interrupts operation of the power circuit in a normal mode to operate in a diagnostic mode In the diagnostic mode the relays are switched in a predetermined sequence to test for a short circuit failure of the master relays or commutated diodes, an open circuit failure of the diodes, an open circuit failure of the master relays, a short circuit failure of the pilot relays and an open circuit failure of any individual pilot relay Upon detection of a failure of a master relay or diode or a short circuit failure of a pilot relay, the master relay and pilot relays for the switching network containing a failed component are de-energized A user discernible signal is generated informing the user that a failure has been detected

Trigger hold circuit for welding power supply

Abstract: A control circuit for an electric arc welder is responsive to the operation of a torch or gun mounted control switch. A first comparator has one input connected to the gun switch and the other input to a reference voltage source. When the gun switch is closed, the output of the comparator will cause a control relay to be energized. When a welding arc is established, a reed switch closes and provides an input to a second comparator which effectively provides a latch to hold the control relay energized. After a predetermined time delay, typically in the order of 1 second, a timer circuit will provide an output to one input of a third comparator, the other input of which is connected to the gun switch. A subsequent closure of the gun switch will caused the output of the third comparator to change the level of the reference voltage, changing the outputs of the first two comparators, thereby removing the latch and deenergizing the control relay. Thus, the control relay can be deenergized either by the welder operating the control switch a second time or by extinguishing the arc, such as by removing the torch from the workpiece; either will disable the latch circuit and terminate the welding operation.

Electronic circuit for tactile sensors

Abstract: An electronic circuit adapted to receive conditioned force signals from a three-axes load cell mounted on the arm of a robot and provide a stop signal for use by a controller of the robot. The circuit compares the sum of the absolute value of the forces with a variable reference signal. A force trip relay and a masking relay are connected in parallel to provide the stop signal when both the resulting sum is greater in value than the reference signal and the robot is in an operating condition in which high forces do not normally occur.

Control circuit for air conditioner

Abstract: In an air conditioner separated into an indoor unit and an outdoor unit, a control circuit comprises a three-phase power source connected in common to the indoor and outdoor units, and a signal line led out from two phases of the power source. A contact of an electromagnetic relay energizing a compressor of the air conditioner is connected on the portion of the signal line in the indoor unit in series with a current sensor sensing the current flowing through the signal line, and a contact of a protective relay protecting the compressor is connected on the portion of the signal line in the outdoor unit in series with the electromagnetic relay. A first controller is disposed in the indoor unit for controlling on-off of the relay contact of the electromagnetic relay, and a second controller is disposed in the outdoor unit for energizing the protective relay contact thereby controlling on-off of the compressor.

Design and Testing of a Microprocessor-Based Distance Relay

Abstract: This paper describes the design and testing of a digital distance relay for high voltage systems. It shows how a prototype has been built using two single board computers in a multiprocessor configuration. This design allows simultaneous real-time filtering of the voltage and current signals and computation of the apparent impedances "in parallel". The paper presents the results of the tests carried out on a prototype of the relay using a transient signal generator test circuit. A trip signal is produced by the relay in less than one 60 Hz cycle after fault occurrence for all faults.

Remote control engine starter

Abstract: A remote control engine starter apparatus for remotely starting an engine. A manually operable transmitter generates a signal, which is detected by a receiver when the receiver, is activated. A timer mounted in the vehicle and connected to the engine battery provides an output at a pre-determined time which connects electrical power through an on/off switch mounted on the vehicle engine to a first relay. The first relay connects electrical power from the vehicle battery to the receiver for powering the receiver. A second relay, energized by the first relay connects power to the starter relay of the engine to provide electrical power to the starter motor of the engine when an output from the timer means and a signal from the transmitter has been detected by the receiver.

Electric vehicle speed control

Abstract: The electric vehicle driven by a DC motor having a field winding. An electric resistance element can be switched into parallel circuit with the field winding to weaken the field and increase potential motor speed. A relay operates the switch, a Hall-effect switch responsive to motor rotation produces voltage pulses indicative of motor speed. A microcomputer counts pulses in a given time period to determine motor speed and compares the speed with that in the prior period to determine whether the motor speed is increasing or decreasing. The computer is programmed to operate the relay to close the switch as the motor speed increases above a first speed and to open the switch as motor speed subsequently decreases to a second speed lower than said first speed. The computer is programmed to respond to a third speed greater than the first speed to operate the relay to open said switch to prevent overspeed. The computer also responds to a fourth speed lower than the third speed and greater than the first speed to operate the relay to close the switch means subsequent to opening said switch at the third speed, thus restoring field weakening after the overspeed has been corrected.

Digitally controlled overload relay

Abstract: An overload relay is provided which monitors current flow in a circuit and triggers an electromagnetic interrupter to open the circuit upon detection of an overcurrent condition. A train of pulses is generated and received by the electromagnetic interrupter for maintaining the circuit closed. The pulse train is terminated upon detection of an overcurrent condition.

Vending machine power switching apparatus

Abstract: An improved vending machine power switching apparatus in which a single power switching circuit is associated with a plurality of load selecting relay switches and a switching control circuit, in which the control circuit controls the order of switching of the power switch and relay switches, such that any relay switch is always closed before power is delivered to its associated load and is always opened after power is removed from the load, and the power is applied and removed by the power switching means.

Multi pole piezoelectrically operating relay

Abstract: This multi pole relay includes: a base plate; several bimorphic elements each of elongate plate shape and including a central electrode of elongate plate shape, a pair of piezoelectric members of elongate thin plate shape arranged on opposite sides of the central electrode, and a pair of surface electrodes arranged on the outer surfaces of the pair of piezoelectric members; a means for fixedly mounting the one ends of the bimorphic elements to the base plate with their other ends free; and, for each one of the bimorphic elements: a fixed contact mounted to the base plate opposing the free end of that one of the bimorphic elements; a flexible element, one end of which is mounted to the base plate, and the other free end of which is interposed between the free end of that one of the bimorphic elements and the fixed contact; and a movable contact mounted on the free end of the flexible element on its side towards the fixed contact and opposing the fixed contact. Thereby, the relay may be made very compact and of very low profile, and accordingly is suitable for fitting to a printed circuit board in conjunction with integrated circuits.

High or low-side state relay with current limiting and operational testing

Abstract: The switch comprises a circuit from a first output terminal via parallel MOS devices in series with current-sensing resistance to a second output terminal, with alternative high-side and low-side configurations having a load between the second terminal and ground, or the first terminal and the DC supply voltage. An input terminal for a digital control signal is coupled via an input diode and two Schmitt Trigger CMOS inverters to a control lead for the gates of the switch. A current overload or short circuit protection circuit coupled between the current-sensor and the input diode comprises two transistors coupled by a diode. A built-in test circuit for indicating the switch condition (on, off, shorted or open) comprises MOS transistors having their gates connected to voltage dividers at the two output terminals, and their drains connected to discrete indication terminals.

Power supply circuit for vehicle

Abstract: A power supply circuit for a vehicle for providing power to motorized accessories, such as power windows and sun roofs, even after the vehicle ignition has been switched off The power supply circuit includes a relay having relay contacts for delivering power to the accessory drive motor, and a relay coil which is energized upon switching on of the vehicle ignition The relay is self-holding and continues to be energized even after the ignition has been switched off However, when a door of the vehicle is opened, as detected by the closing of a door switch, the relay coil is de-energized and power to the accessory drive motor is terminated In an alternative embodiment, power to the accessory drive motor is not terminated until after sequential opening and closing of a vehicle door

Method for determining the direction of the origin of a disturbance affecting an element of an electrical energy transfer network

Abstract: A directional relay for providing indication of the direction of a fault on an electric power transfer network has an adder (9), a subtractor (10) and filters (11) which receive signals from voltage and current transformers (6,7) and derive signals related to fault-induced forward and backward transient waves on the network. To ensure reliable operation even when the relay is close to a low impedance element such as a generator (2), the forward wave related signal is delayed in a delay unit (12) by an amount equal to the propagation time of the wave along the section protected by the relay, before the difference between its square and that of the backward wave related signal are integrated (16) to derive the fault direction signal. If the protected section has a low distributed capacitance, the voltage and current signals can instead be combined by a differentiator (22) and adder (23) and filtered (11B) to produce a signal related to the forward transient wave appearing at a point X along the protected section. The integrator (16) receives the product of this signal and the filtered current signal.

Circuit arrangement for switching an electric-motor drive on and off

Abstract: A circuit arrangement is proposed for switching an electric-motor drive on and off, preferably into or between two defined limit positions, in that the drive motor is intended to be electrically braked during switching off, with as little delay as possible, by short-circuiting the motor winding. To this end, the circuit arrangement comprises two relays (14, 15) which are connected by means of in each case one changeover contact (14a, 15a) to a connecting lead (12, 13) of the drive motor (11), and the break contacts (14c, 15c) of the relay (14, 15) being connected to one another at one terminal and the make contacts (14b, 15b) being connected to one another at the other terminal of a supply voltage. When the drive is operated, the one relay (15) is initially switched on for a specific rotation direction, and the motor is connected to the voltage via the changeover contact (15c) of this relay. When the motor (11) is switched off, the other relay (14) is additionally also switched on, and the motor (11) is electrically braked, subject to the short pull-in delay of the relay (14), via the changeover contact (14a) of said relay (Figure 1).

Alternating current driven piezoelectric latching relay and method of operation

Abstract: An alternating current latching relay is provided which employs a latching-type, mechanically operated snap-action switch mechanism with a set of electric contacts that are selectively latched either in the open or closed condition in a snap-action manner upon successive actuations of the snap-action mechanism by suitable push rod means for initiating its operation. At least one alternating current excited bender-type piezoelectric drive member has one end secured to a common base member with the latching-type snap-action switch mechanism and the remaining free end engaging the push rod means. An alternating current electric excitation signal is directly applied to the piezoelectric plate elements of the bender-type drive member for mechanically vibrating the bender-type drive member in a manner such that its amplitude of vibration quickly builds up to a value where it repeatedly strikes the push rod means with sufficient force to selectively actuate the snap-action switch mechanism to the opposite one of its two operating conditions from that in which it originally was set. A tuning mass in the form of a slug element is secured to the end of the bender-type drive member to reduce the natural resonant frequency of vibration of the bender-type drive member to substantially the frequency of the alternating current excitation signal to thereby increase the amplitude of its vibrations to a maximum. Additionally, the tuning mass increases the impulse delivered by the bender-type drive member to the push rod for actuating the snap-action mechanism.

Emergency battery cell monitor

Abstract: A wet cell battery monitor developed to monitor both electrolyte fluid level and electrolyte fluid charge (specific gravity) of a single cell. The monitor includes a probe and appropriate circuitry. The probe is adapted for insertion into a cell for monitoring and is connected to two circuits which are interconnected. Both include resistors, preferably variable, and include induction coil type relay switches. Blocking diodes are preferably used to maintain the independent integrity of each of the two circuit, one which warns of fluid level drop off and the other of a decrease in electrolyte fluid charge. The two circuits each drop off independenly in response to specific gravity (state of charge) and to fluid level, respectively, setting off alarms, e.g. visual or audio signals.

Music on hold for key systems

Abstract: A music on hold system is provided for key telephone systems having key stations, central office lines, and a muting relay for load resistance termination of the central office lines when they are on hold. A music source provides a music signal which is applied to the muting relay. When the telephone system controller receives a hold command from a key station, it generates a hold signal and applies the hold signal to the muting relay. In response to the hold signal, the muting relay applies the music signal to the central office line. Before being applied to the muting relay, the music signal is conditioned by passage through a gain control, a high frequency cut off filter, an amplifier, and a DC level shifter.

Combined magnetic and thermal relay and circuits for timed alarms and lamps of vehicles

Abstract: A combined magnetic and thermal activated relay for use in alarm systems. The relay includes a thermal activated bimetal switch in series with the current through the magnetic coil which activates a magnetic switch. The thermal switch is in a normally closed state and the magnetic switch is in a normally open state. When current passes through the coil the magnetic switch changes from its normally open to a closed state applying voltage potential for an external requirement. The heat generated by the coil's resistance to current flow heats the core of the magnetic coil, and after reaching an elevated temperature level the thermal activated switch changes from its normally closed state to an open state opening the current flow path through the magnetic coil causing the magnetic switch to return to its normal open state removing voltage for the external requirement. The switching operation of the thermal switch cycles with temperature changes. The time between cycles can be selected by coil varying the size of the core, size of the coil wire, the number of turns of the coil wire or the type of metal used in the bimetal rotor.