Showing papers on "Relay published in 1982"

Development and Testing of an Electro-Mechanical Relay to Detect Fallen Distribution Conductors

Abstract: If undetected by phase or ground overcurrent relaying methods, fallen distribution conductors or high impedance faults may be a fire hazard and a threat to public safety. Four promising relay schemes to detect these faults are evaluated using both digital and analog techniques and one scheme was chosen for prototype construction. In the light of economic and performance data, a prototype Ratio Ground Relay has been constructed for installation and testing on six Pennsylvania Power and Light distribution feeders.

Apparatus for control of load power consumption

Abstract: An apparatus for reducing the voltage applied to a load in an AC system utilizes an autotransformer and a relay or equivalent switching device between the common winding and the series winding. In each of the AC lines, the common winding and relay are connected between the load and the AC common while the series winding is connected between the input and the output. The relay is normally open to pass substantially full input voltage to the load, but when closed the relay permits current flow in the common winding to reduce voltage to the load. The relay or equivalent switching is therefore not in the direct flow of load current and can be of lower current rating and smaller size and cost as compared to prior art voltage reduction systems.

Solid state relay circuit employing MOSFET power switching devices

Abstract: A solid state relay employing MOSFET power switching devices is disclosed A d-c output relay is disclosed using a single power MOSFET device and an a-c output relay is disclosed employing series opposition power MOSFETS

Battery scanning system

Abstract: A battery scanning system which is capable of monitoring and displaying theoltage of each cell in a battery or upon command provides the cell voltage distribution by displaying the cell number and voltage value of highest and lowest cell. The system has a digital logic system, display, input switches for operator generated variables, an alarm, relays, relay selection gates, an optically coupled isolation amplifier, power source and an analog-digital converter. The optically coupled analog amplifier electrically isolates the system from the battery so that large voltage offsets will not adversely affect the automatic measuring of the cells.

Optimal Relay and Saturating Control System Synthesis

Abstract: Introducing a new hobby for other people may inspire them to join with you. Reading, as one of mutual hobby, is considered as the very easy hobby to do. But, many people are not interested in this hobby. Why? Boring is the reason of why. However, this feel actually can deal with the book and time of you reading. Yeah, one that we will refer to break the boredom in reading is choosing optimal relay and saturating control system synthesis as the reading material.

A Prototype of Multiprocessor Based Distance Relay

Abstract: This paper concerns the design and realization of a digital relay for EHV systems. It describes the algorithm which has been used and the main principles of operation. Then it shows how a prototype has been built with four 16-bit microprocessors, to allow the simultaneous real-time computation of three apparent impedances. The hardware and software architecture are described. The paper also presents the results of the tests carried out on the relay: a tripping signal is sent within one period of 50 Hz for all faults (half a period for near-by short-circuits). Furthermore, single-phase tripping, directional discrimination and power-swing detection are provided.

Generator Ground Fault Protection Using Overcurrent, Overvoltage, and Undervoltage Relays

Abstract: This paper describes the protective relaying schemes employed by Georgia Power Company to protect synchronous generators from single-phase- to-ground faults. Three types of relays are connected in the secondary of a distribution grounding transformer. These include a conventional electro- mechanical overcurrent relay with time overcurrent unit and instantaneous overcurrent unit, a solid- state overvoltage relay (with timing module) tuned to reject frequencies near 180 hertz, and a solid-state undervoltage relay (with timer) tuned to reject frequencies near 60 hertz present at the generator neutral. The proper method of selecting the generator grounding components and protective relays is described, and detailed setting instructions for all relays are also included.

Cordless telephone set

Abstract: 1. Cordless telephone set as well as fixed relay station which exclusively corresponds with the telephone set or with telephone sets of one subscriber station connected in parallel, for telephone calls using the public network, said telephone set as well as said relay station, which is directly connected to the telephone network, each comprising a radio transmitter and a radio receiver, and the transmitters exchanging identification signals for avoiding wrong connections, characterized in that the transmitters (4, 14) are provided with a coding device (7, 17) for generating the identification signal or -signals in order to transmit a code on a channel identified as being idle by the corresponding receiver (3, 13), the code of the transmitters (4, 14) being invariable and independent from the dialled telephone number of a subscriber station, that the receivers (3, 14) are provided with a scanner for distinguishing between free and busy channels from a plurality of present communication channels or pairs of communication channels respectively, and that a comparator (9, 19) is located after the receivers (3, 13) which seizes the transmitted invariable code and compares it with the receiver-side code, as well as a circuit to establish the cordless connection especially in duplex operation between the telephone set and the telephone relay station in case of code identity detected in the comparator (9, 19) circuit.

Liquid level control

Abstract: Improved apparatus for providing both a liquid level control and a low water cut-off for boilers and the like, having only a single probe and a single relay

Time-delay current sensing circuit breaker relay

Abstract: A circuit control device combining the functions of a current sensor, a time delay circuit, an undervoltage sensor, and a lockout such that, once tripped, the device must be reset intentionally. The current sensor includes a coil (16a) surrounding two reed switches (18, 20), the reed elements (18a, 20a) of each of which being perpendicular to those of the other for vibration resistance. The coil is then surrounded by a magnetic shield (28) in order to shield out some of the leakage flux from the main relay coil (14c). The time delay circuit includes a PUT (Q1) which compares a steady voltage from a voltage divider network with the increasing voltage across a capacitor (C3). The undervoltage sensor includes a second PUT (Q3) which compares the voltage of the DC source (10) with the steady voltage across a zener diode (D5). In each case the cathode of the PUT is connected to the gate of an SCR (Q2) which, when gated "ON," energizes the trip coil (24c) of the latching relay (24), which in turn opens the main relay (14). This also closes another set of contacts (24e, 24f) in the latching relay, which activates a visual "tripped" indicator. The device also includes a reset coil (24d) to reclose the latching relay, an override switch (SW3) to energize the main relay coil regardless of the status of the latching relay, and an energy-storing capacitor (C2) to power the time delay circuit even when the DC source voltage drops too low to do so.

Fault detection arrangement for relay switching system

Abstract: An arrangement for detecting faults in automatic test systems of the type wherein test points in a unit under test are connected to test instruments by the programmed closure of electromechanical relay contacts Respective contacts of the relays are connected to each other and, during periods intermediate of the closure of the relays, a detector circuit is coupled to the interconnected relay contacts The detector circuit compares a voltage or resistance present on the interconnected relay contacts to a threshold In one embodiment, if a difference between a signal on the interconnected relay contacts and the threshold persists for a predetermined period, an interrupt signal is generated which prevents further closures of the relays In this manner, catastrophic failures of the unit under test and the test instruments are prevented

Degaussing circuit for television receiver having switched mode power supply

Abstract: A switched mode power supply for a remote controlled television receiver incorporates a degaussing circuit having a relay that is required to be energized in order to permit operation of the degaussing circuit. Power to energize the relay is derived from a power supply switch transistor protection circuit which removes residual stored energy from the power transformer primary winding. This stored energy is used to charge a capacitor during the time the switch transistor is nonconductive. The capacitor is discharged to provide current to energize the deguassing circuit relay in order to permit ac mains current to flow through the degaussing coil.

Amplifier power supply controlled by audio signal

Abstract: A power control circuit (22) for selectively supplying power from a constantly available power source (20) to an amplified speaker (12) by sensing the existence of an audio signal in a differential stage by determining the differential potential signal between leads (16, 18) to produce a ground reference signal which is amplified by a transistor (28) and thereafter rectified (52) to provide a direct current signal which operates a relay driver transistor (42) which, in turn, operates a relay switch (46) to supply power to the speaker amplifier (14). The discontinuance of power to the speaker amplifier is delayed for a period of time after the discontinuance of the audio signal to the differential stage (24) by placing a capacitor (58) between the rectifier and the relay driver transistor (42) to power the relay driver transistor for a period of time after the audio signal is no longer being provided.

Electronic control system for overload relay or the like

Abstract: A control is provided for an AC circuit protection system or the like which is capable of monitoring either single phase or polyphase current flow. The composite current is periodically sampled at a frequency f s which is not a harmonic frequency of circuit current. The current sample values are converted into digital form and processed, then stored in an accumulator stage. When an overcurrent condition occurs the accumulator stage overflows and trips a circuit interrupter.

Protective relay apparatus

Abstract: A protective relay system for providing pilot protection for two and three terminal alternating current transmission lines, which system does not require a continuous metallic circuit between the relaying points. The evaluation circuit develops operating and restraining quantities, modified by a predetermined constant which determines the operating characteristic of the relay system.

Overvoltage directional relay

Abstract: Disclosed is an overvoltage directional relay that forms a part of a relay system which provides protection for a high voltage three phase transmission line. The overvoltage directional relay provides a high speed blocking function for use with the high speed tripping functions in the protective relay system. In one embodiment the directional relay utilizes the negative-sequence components of the three phase transmission lines. In another embodiment the directional relay utilizes the zero-sequence component of the three phase transmission line.

Controlled switch circuit for resistive and inductive loads - has parallel connected semiconductor switch and electromagnetic relay switching in sequence across load, and zero-crossing detector

Abstract: The alternating current switch uses two switching elements in parallel across the load and either, or both, may be on or off. One element is a semiconductor switch (6), such as a triac or a thyristor, and the other (7) is an electromagnetic relay. A zero-crossing detector (4) fed by mains-derived alternating current (a) creates a train of pulses (6) which are ANDed with a control switching pulse (c) in a logic gate (9). The output (d) from the gate is fed to control and driver circuits (10,11) which drive the semi-conductor and electromagnetic switches. The semiconductor switch is fired in synchronisation with a zero-point in the alternating current cycle, thus achieving a change-over at a point of low circuit current. After the intrinsic switch-on delay, the relay is switched on in parallel. Since the current is already established, radio-frequency arcing interference at contact is eliminated. The control circuit (10) now switches the semiconductor switch off to avoid heating of this element. The semiconductor switch is brought on again just before the relay is switched off, and then off again to open the load circuit.

Latch relay drive circuit

Abstract: A latch-relay drive circuit includes a pair of switching devices for separately energizing the set and reset latch-relay coils. To prevent the latch-relay from remaining set once the power fails, an energy storage device, such as a capacitor charged from the power supply, is automatically switched across the reset coil by a switching circuit once the power supply voltage drops below a predetermined voltage thereby automatically resetting the relay.

Compact relay system

Abstract: An improved relay assembly comprising a relay, a circuit board and a base in which the relay is directly mounted to the circuit board terminals are mounted to the board and the assembly of relay board and terminals is then inserted and retained in the base. Interconnecting circuitry for connecting the terminals to the various elements of the relay and also for carrying out other chosen functions is provided by the circuit board and the connection of the relay and terminals to the board is carried out by one step soldering. The whole may be placed in the housing and be hermetically sealed. Variations of terminal structure arrangements for improved rigidity and reliability are described as well as details of relay structure and contact mounting.

Productive relay apparatus for protection from sub-synchronous current oscillations in a power system

Abstract: A protective relay for protecting a power system from sub-synchronous current oscillations. The protective relay determines both the amplitude and frequency of sub-synchronous current oscillations occurring in the power system. A series of logic relationships, based in part on the parameters of the power system, are implemented by the protective relay such that when the frequency and amplitude of the sub-synchronous oscillation signal satisfy these relationships a trip signal is produced.

Vital solid state relay for railroad alternating current track circuits

Abstract: This vital solid state relay incorporates only passive elements and is intended for use as a replacement for a two element AC track relay in AC track circuits The local input signal is applied to a transformer whose secondary output, across a Zener diode, is a pulsed, square wave DC with regulated peak The track input is applied through a noise rejection filter, tuned to track circuit frequency, to a coupling transformer A series loop registry circuit includes the secondary of each transformer, a DC relay, and a varistor element The sum of the transformer output signals, due to the Zener diode rectification, has a DC component When local and track signals are both present and substantially in phase, the varistor switches to its high current condition to pick up the DC relay to indicate an unoccupied track section Absence of the track input, out of phase conditions, or unmatched frequencies retains the varistor in its low current state and the DC relay releases to register an occupied section

A New Techniques of Differential Relaying the Differential Relay

Abstract: Standard percentage differential relaying with through current restraint is insensitive to high impedance (i.e. low fault current) faults when applied to apparatus which experience substantial, near 1.0 pu, prefault through currents. A new technique of differential protection is proposed which considers only fault contribution currents through the use of microcomputer cancellation of the prefault through currents. This new form of differential relaying maintains the external fault selectivity of standard percentage differential relaying, has a large buffer zone between the tripping and restraint zones of relay operation, and is substantially more sensitive to high impedance faults than the standard arrangement. This paper presents the theory for this relay, a simplified analysis of the effects of CT errors on the relay operation, and the experimental results for a real time laboratory version of the relay using a 16-bit single- board microcomputer.

High frequency heating appliance having protection against rush currents

Abstract: A high frequency heating appliance has a monitor circuit for a door switch, wherein a current-limiting resistor and a fuse are provided in the monitor circuit for the door switch and serve as components of a bypass circuit for a relay. This arrangement prevents a large current from flowing when monitoring faults with the door switch and also prevents a rush current from flowing during normal operation.

A Log-Tabel Based Algorithm For Implementing Microprocessor Time-Overcurrent Relays

Abstract: The difficulties that arise in implementing the time-overcurrent relay characteristic on microprocessor systems are due mainly to two factors. Firstly, data acquisition is usually linear whereas curve scales are logarithmic. Secondly, we have to calculate the main variable, namely the normalized fault current given as the ratio of the measured line current to the preset pickup value in a system in which the latter quantity should preferably be adjustable.

Control circuit system for automobiles

Abstract: A control circuit system for an automobile comprises a plurality of command switches (including an electric horn switch) all provided on a steering wheel. A control circuit is provided to generate a control signal in response to each command signal from the switches, and a signal coupling element is provided to connect the switches and the control circuit through a single signal line conventionally used for the electric horn switch. Operation of the automobile horn is enabled through a normally-closed relay even when a power switch connecting the automobile battery and the control circuit is open, thereby eliminating continuous drain on the automobile battery by a dormant but powered control circuit.

Optical arc discharge detector for encapsulated installations - uses inbuilt light source for testing operation of protection circuits

Abstract: The application is particularly to metal encapsulated high gas pressure, for example sulphur hexafluoride,busbar and switchgear installations. The presence of an arc between conductor and encapsulation is detected by an optical sensor (1a-1n) inside the corresponding duct section. The sensor transmits an electrical signal to an external protection relay (4) which initiates the circuit breaker tripping relay (5). In the case of a detector in a circuit breaker section a time delay unit is incorporated in the electrical signal path. To test the detectors built in light sources (6a-6n) are incorporated. These can be energised through their respective switches (7a-7n), having first isolated (10) the tripping circuit. When the selected detector responds the sensing relay (4) operates and an auxiliary contact on it brings up a lamp to signal correct operation. PS.

Optical transmission system

Abstract: PURPOSE:To enable stable optical transmission and to increase the reliability of system, by feeding power only when switched from the existing use to a spare system, in a relay device for optical transmission CONSTITUTION:When a current directs toward solid lines 19 in a relay device 3, since a Zener diode ZD116 is in reverse direction and a ZD217 is in forward direction, an existing relay device 4 receives power supply for operation, but a spare relay device 5 is not actuated If a failure is taken place in the device 4, it is detected at a monitor circuit 11 of a terminal station 9 When the direction of power feeding current is switched to dotted lines 18, since the ZD116 is in forward direction and the ZD217 is in reverse direction, power is given to the spare relay device 5, the device 4 is not operated, allowing to switch the system of existing and spare

Transient over-voltage protection circuit

Abstract: A transient over-voltage suppressor circuit for a motor vehicle power supply system that includes a diode-rectified alternating current generator. The suppressor circuit comprises a dual coil relay, a Zener diode and a small resistor having a positive temperature coefficient of resistance. The Zener diode and relay coils are connected across the output terminals of a bridge rectifier connected to the generator and when a transient over-voltage occurs the contacts of the relay are closed. When the relay contacts close they connect the resistor and one of the relay coils across the output terminals of the bridge rectifier. The relay contacts open when the resistance of the resistor increases to a predetermined value.