Showing papers on "Relay published in 2000"

Energy-efficient antenna sharing and relaying for wireless networks

Abstract: We develop energy-efficient transmission protocols for wireless networks that exploit spatial diversity created by antenna sharing: coordinated transmission and/or processing by several distributed radios. We focus on single-user transmission and examine several possibilities for the strategy employed by the assisting radio, or relay, including decoding and forwarding as well as amplifying and forwarding. In each case, we develop receivers based upon maximum-likelihood and/or maximum signal-to-noise ratio criteria, relate their structures, and compare their bit-error probability performance by means of analysis and simulations. We cast single-hop and multihop routing into our framework for comparison purposes. All of our antenna sharing protocols offer diversity gains over single-hop and multihop transmission, and our results suggest that low-complexity amplifying and forwarding is energy-efficient in spite of noise amplification at the relay.

Multipoint Relaying: An Efficient Technique for Flooding in Mobile Wireless Networks

Abstract: In this paper we discuss the mechanism of multipoint relays (MPRs) to efficiently do the flooding of broadcast messages in the mobile wireless networks. Multipoint relaying is a technique to reduce the number of redundant re-transmissions while diffusing a broadcast message in the network. We discuss the principle and the functioning of MPRs, and propose a heuristic to select these MPRs in a mobile wireless environment. We also analyze the complexity of this heuristic and prove that the computation of a multipoin- t relay set with minimal size is NP-complete. Finally, we present some simulation results to show the efficiency of multipoint relays.

Location position system for relay assisted tracking

Abstract: An extensible short-range tracking system is disclosed. The tracking system disclosed is a multi-level tracking system. At the first level is an RF tag, which is a transmit-only unit that transmits information including minimally an identification number. The transmission from the RF tags are sporadic with timing depending upon the application at implementation. Generally, the transmission timing comprises a transmission, which is repeated periodically at random times. Transmissions from the RF tags are received in a series of relays. The relays may calculate the position of the tags by knowing the position of the relays and the time difference of arrival of the signals from the RF tags by several relays or may pass the information needed to calculate position to a base station. Alternately, the RF tags may generate position information and transmit that information along with the RF tag identifier to the relays. The relays, which may be networked among themselves, then relay the information from the tags to a base station unit. The base station unit may be part of various applications such as a fire control system in a military application or an inventory system in an industrial application.

On the white Gaussian multiple-access relay channel

Abstract: The spectral efficiency of mobile radio networks can be improved by allowing each mobile station to act as a relay for one other mobile station. One can expect further performance improvement if each relay aids not just a single mobile station, but many simultaneously. We attempt to quantify this improvement by introducing the multiple-access relay channel (MARC) and deriving capacity results for it. Capacity outer and inner bounds for it are derived.

Adaptive relay setting for flexible AC transmission systems (FACTS)

Abstract: The paper presents an apparent impedance calculation procedure for distance relaying of transmission lines involving FACTS devices, particularly the UPFC (unified power flow controller). The presence of UPFC significantly affects the trip boundaries which are also adversely affected by fault resistance combined with remote end infeed. Depending on the UPFC location, the trip boundary is influenced by the fault location, prefault condition, the arc fault resistance and the parameters of the UPFC itself (series voltage magnitude and phase angle). The adaptive nature of this protection scheme necessitates the use of a neural network for generation of trip boundaries.

Charging station for electric-powered vehicles

Abstract: A charging station includes a plurality of charging sockets, each of which is adapted to be connected to an electric-powered vehicle, and a plurality of switch units, each of which includes a relay switch that interconnects a power supplying circuit and a respective charging socket, and a trigger member connected to the relay switch and controllable so as to control in turn the relay switch to make or break electrical connection between the power supplying circuit and the respective charging socket. A current monitoring unit generates output signals corresponding to amount of current flowing through each of the charging sockets. A processing unit receives the output signals from the current monitoring unit, and controls the trigger members of the switch units to ensure the total amount of current flow through the charging sockets does not exceed a rated current value for the charging station.

Stand alone intelligent digital distance relay

Abstract: Remote end infeed causes problems in distance relay especially under high resistance earth fault conditions. Although a distance relay set to an ideal operating region can cover the fault resistance at one particular load condition, the operating region is affected by changes in load condition. Hence a distance relay may overreach or underreach when load changes. From the main factors which affect the ideal digital distance relay operating region, a stand alone intelligent digital distance relay which can adapt to these changes is presented. This approach does not need communication links from the remote end of the line or the system control center. Numerous computer simulations have been carried out on realistic system configurations and the results show that there is a high potential for developing an intelligent digital distance relay.

A study of a loop interference canceller for the relay stations in an SFN for digital terrestrial broadcasting

Abstract: In each relay station in an SFN (single frequency network) for DTB (digital terrestrial broadcasting), the loop interference is caused by the coupling from the transmitting antenna to receiving antenna. The interference must be reduced to an allowable level in order to avoid problems with distortion and oscillation. We propose a frequency-domain adaptive cancellation algorithm using reference signals carried in the OFDM signal. The principle of the proposed algorithm is outlined and the usefulness of the algorithm is verified by the results of computer simulations.

iCAR: an integrated cellular and ad-hoc relay system

Abstract: Ever increasing data traffic and limited capacity are major causes for congestion in current cellular systems. This paper presents a new architecture for the next generation wireless systems based on the integration of the cellular infrastructure and modern ad-hoc relaying technologies. The new architecture can efficiently balance traffic loads between cells by using ad-hoc relay stations (ARS) to relay traffic from one cell to another cell dynamically. This can not only increase a system's capacity cost-effectively, but also reduce transmission power for mobile hosts, and provide services for shadow areas. In this paper, we present the architectural concept including its basic operations and principal benefits. We also propose a seed-growing approach for ARS placement, and discuss the upper bound on the number of seed ARSs needed in the system. We evaluate the performance improvement of the new architecture through analysis and simulations.

Adaptive relay setting for flexible AC transmission systems (FACTS)

Abstract: Summary form only given as follows. The paper presents an apparent impedance calculation procedure for the distance relaying of power transmission lines involving FACTS devices, particularly the UPFC (unified power flow controller). The presence of UPFC significantly affects the trip boundaries which are also adversely affected by fault resistance combined with remote end infeed. Depending on the UPFC location, the trip boundary is influenced by the fault location, prefault condition, the arc fault resistance and the parameters of the UPFC itself (series voltage magnitude and phase angle). The adaptive nature of this protection scheme necessitates the use of a neural network for generation of trip boundaries.

Electronically switching latching micro-magnetic relay and method of operating same

Abstract: According to various embodiments of the invention, a relay is suitably formed to exhibit an open state and a closed state. The relay is operated by providing a cantilever sensitive to magnetic fields such that the cantilever exhibits a first state corresponding to the open state of the relay and a second state corresponding to the closed state of the relay. A first magnetic field may be provided to induce a magnetic torque in the cantilever, and the cantilever may be switched between the first state and the second state with a second magnetic field that may be generated by, for example, a conductor formed on a substrate with the relay.

Contents transfer method and network system, and machine-readable recording medium with program recorded therein

Abstract: PROBLEM TO BE SOLVED: To provide a contents transfer method by which contents having no urgency such as contents looked ahead by a cache server are transferred without giving much effect on other traffic. SOLUTION: In the case of looking ahead newest contents that may be accessed from terminal T1 with high possibility, a relay control cache server C1 allows a Web server S1 storing the contents to transfer the contents to a relay server M2 and allows the relay server M2 to transfer the contents to a relay server M1, and finally allows the relay server M1 to transfer the contents to the relay control cache server C1. Since the band consumption at a point of time can be decreased in comparison with the case of directly transferring the contents from the Web server S1 to the relay control cache server C1, the effect given on other traffic can be reduced. COPYRIGHT: (C)2002,JPO

Integrated soft starter for electric motor

Abstract: A solid state motor starter, commonly referred to as a soft starter, is constructed in a manner to be easily manufacturable while at the same time combining all the required components in a relatively small package. A solid state power switch is clamped between a pair of bus bars in an offset manner to accommodate a discrete switching relay mounted in an inverted manner between the line input and the bus bar in communication with the load outputs. When in a motor run node, current is shunted away from the solid state power switching device and through the switching relay, a substantially linear current path is achieved to reduce power loss and heat buildup. The arrangement allows for a heat sink mounted to one of the bus bars with adequate spacing between the heat sink and the discrete relay for insertion of a cooling fan. Current sensing is achieved with a Hall effect sensor mounted to the bus bar in a small current sensing region that is created by having a pair of slots in the bus bar to direct current. A pair of magnetic pins extend perpendicular from the bus bar to create the magnetic flux for the Hall effect/sensor to sense current flow through the current sensing region. The Hall effect sensor circuit board also contains a thermistor which is mounted with adequate insulation yet in thermal communication with the bus bar.

Water detection system and method

Abstract: A water detection system for detecting water and activating an alarm is provided The water detection system includes an alarm relay and a water sensor The water sensor includes a solid state switching and amplifying circuit for detecting low levels of current flow and amplifying the signal to activate the alarm relay In one embodiment, the water detection system further includes an alarm panel, including visual and audible alarms activated by the alarm relay In one embodiment, the water detection system includes multiple water sensors for providing zone protection In one embodiment, the alarm relay is configured to shut-down the device causing the presence of water A method for implementation of the water detection system is also provided

Data transmission method and system, and device used therefor

Abstract: A system including a central unit (10), a terminal (20), and a relay device (30) relay transmission of isochronous data effectively, in a time-sharing manner. The central unit (10) cyclically carries out the polling. In response to the polling, the terminal (20) transmits a plurality of frames. The relay device (30) detects that the plurality of frames transmitted from the terminal (20) via a transmission path (40) are completely received based on carrier-sensing by a carrier detecting portion (308) incorporated in the relay device (30). The relay device (30) , at the time of detection, transmits frames received thereby without error to the central unit (10).

Positional protection of transmission systems using Global Positioning System

Abstract: This paper presents a new technique for the protection of power transmission systems by using the Global Positioning System (GPS) and fault generated transients. In the scheme, the relay contains a fault transient detection system together with a communication unit, which is connected to the power line through the high voltage coupling capacitors of the CVT. Relays are installed at each busbar in a transmission network. These detect the fault generated high frequency voltage transient signals and record the time instant corresponding to when the initial travelling wave generated by the fault arrives at that busbar. The communication unit is used to transmit and receive coded digital signals of the local information to and from the associated relay(s) in the system. At each substation, the relays determine the location of the fault by comparing the GPS time stamps measured locally with those received from the adjacent substations. Extensive simulation studies presented in the paper demonstrate the feasibility of the scheme.

Performance Analysis of Traditional and Improved Transformer Differential Protective Relays

Abstract: This paper describes a new approach for transformer differential protection that ensures security for external faults, inrush, and overexcitation conditions and provides dependability for internal faults. This approach combines harmonic restraint and blocking methods with a wave shape recognition technique. First, we review the concept of transformer differential protection. We then analyze magnetizing inrush, overexcitation, and current transformer (CT) saturation phenomena as possible causes of relay misoperation. After summarizing the existing methods for discriminating internal faults from inrush and overexcitation conditions, we propose a new approach for transformer differential protection and describe the relay that is based on this approach. Finally, we compare the behavior of some of these methods for real cases of magnetizing inrush conditions. INTRODUCTION Three characteristics generally provide means for detecting transformer internal faults [1]. These characteristics include an increase in phase currents, an increase in the differential current, and gas formation caused by the fault arc [2], [3]. When transformer internal faults occur, immediate disconnection of the faulted transformer is necessary to avoid extensive damage and/or preserve power system stability and power quality. Three types of protection are normally used to detect these faults: overcurrent protection for phase currents, differential protection for differential currents, and gas accumulator or rate-of-pressure-rise protection for arcing faults. Overcurrent protection with fuses or relays provided the first type of transformer fault protection [4]; it continues to be applied in small capacity transformers. Connecting an inverse-time overcurrent relay in the paralleled secondaries of the current transformers introduced the differential principle to transformer protection [4]. The percentage differential principle [5], which was immediately applied to transformer protection [4], [6], [7], provided excellent results in improving the security of differential protection for external faults with CT saturation. This analysis will focus primarily on differential protection. Differential relays are prone to misoperation in the presence of transformer inrush currents, which result from transients in transformer magnetic flux. The first solution to this problem was to introduce an intentional time delay in the differential relay [4], [6]. Another proposal was to desensitize the relay for a given time, to override the inrush condition [6], [7]. Others suggested adding a voltage signal to restrain [4] or to supervise the differential relay [8]. Researchers quickly recognized that the harmonic content of the differential current provided information that helped differentiate faults from inrush conditions. Kennedy and Hayward proposed a differential relay with only harmonic restraint for bus protection [9]. Hayward [10]

Adaptive setting of digital relay for transmission line protection

Abstract: The distance relay is the most widely relay used in transmission line protection because it is applicable not only as main protection but also as back-up protection. However, the protection range of the distance relay is always fixed in the unchangeable operating range while the power system varies and therefore the distance relay is the one that is the most highly influenced by the power system changes. In this regard, this paper describes an approach to minimize the maloperation of the distance relay due to the power system changes through changing protection range of the distance relay into optimal condition in response to the load variation and power system condition. Also malfunction of the distance relay in case of high resistance ground faults could be minimized through modeling the protection range into a quadratic function.

Agent technology applied to adaptive relay setting for multi-terminal lines

Abstract: This paper discusses the adaptation of the settings of distance relays for multi-terminal lines employing agents. Agents are software processes capable of searching for information in networks, interacting with pieces of equipment and performing tasks on behalf of their owners (relays). Results illustrating the performance of the adaptive method proposed compared to conventional fixed settings are presented. It is shown that the digital relays and agents acting within a communication structure (also called middleware) can alter adaptive settings to ensure correct performance over a wide variety of operation conditions, without the need of an additional communication link. The proposed relaying scheme can also be utilized for first zone clearing over the entire line.

Method and arrangement for handling information packets via user selectable relay nodes

Abstract: The invention is related to a method in a communication network for handling traffic, such as data packets, from source nodes to destination nodes, via user selectable relay nodes. The relay nodes form an overlay network of nodes operated and managed by an overlay network operator. Communication between relay nodes relies on using packet forwarding services of intermediate networks being operated and managed independently by other operators. For any source/destination pair the overlay network operator may select an appropriate sequence of relay nodes to be passed depending on the required quality of service and the performance of different intermediate networks. The invention enables the control of the spreading of traffic between any two end-points over several alternative relay routes.

A new method for protection zone selection in microprocessor-based bus relays

Abstract: Use of graph theory simplifies representation of complex bus arrangements in power system stations. This paper presents a new method, based upon graph theory, for selecting bus protection zones in microprocessor-based relays. We use a typical bus arrangement to illustrate the graphical representation of station arrangements, graph operations, and associated matrix operations. We also describe an implementation of the zone selection method and use two examples to demonstrate the advantages of the method. Using the status of switching devices in the station, the zone selection method provides the relay with real-time bus arrangement information. The bus relay uses this information to assign input currents to a differential protection zone and to select which breakers to trip for a bus fault or breaker failure.

Secure switching device for on-off switching of electrical load has at least 2 switching elements each providing switch output for controlling load

Abstract: The secure switching device has at least 2 electronic switching elements (56,58) receiving the same switching signal, for providing an output signal with 2 alternate potentials, each of the switching elements coupled to a respective output terminal (76,78), for on-off switching of an electrical load (84) via a relay (80). An Independent claim for a secure switching device system is also included.

Highway grade crossing vehicle violation detector

Abstract: In one embodiment, the present invention is an alarm monitor for a railroad grade crossing, the grade crossing having an island activation relay that is activated in response to an approaching train, the alarm monitor including a micropower impulse radar (MIR) responsive to pedestrians and motor vehicles in a prohibited area of the crossing island during activations of the island activation relay; and a processor configured to generate a warning signal when the MIR detects a pedestrian or a motor vehicle in the prohibited area during an activation of the island activation relay.

Solid state electrical switch

Abstract: A 2-terminal solid state electrical switch is provided which can be connected in series with a load device in a the same manner as a conventional mechanical-contact switch, does not leak current during an "OFF" state, and operates from a dynamic pulse run mode during an "ON" state. The two-terminal solid state electrical switch of the present invention requires neither a power supply to operate, nor any mechanical movement and contact points. Consequently, no spark, arc or any mechanical noise is created in the solid state electrical switch's operation, nor does it corrode, thus allowing it to be used in a hostile environment. The solid state switch of the present invention can be put to uses not practical for conventional mechanical-contact switches, such as to control multi-appliances, as static circuit breakers, contactors and relays for fire-proof, explosion-proof, water-proof, anti-chemical, anti-corrosion, humidity resistant, dust resistant, anti-vibrations and heavy duty frequently operations. Further, a unique initialization circuit in the solid switch of the present invention resets the switch intelligently to a suitable operating mode after a power interruption, thus avoiding accidents that may endanger property and lives. The present invention also provides a highly isolated multi-point random remote control switch/relay suitable for wide industrial and other applications.

“Relay” and “support” translations

Abstract: This article focuses on the fact that much translation is not made directly between the source language of the original and the target language in hand, but may have passed intermediary third (fourth etc.) languages. It is argued that, since most intermediary realisations have been made for actual audiences, it would be more precise to term such realisations ‘relays’ for other target texts, and reserve the term ‘indirect translation’ for cases where there are no genuine consumers of intermediate realisations. The article further points out that translators sometimes consult translations into other languages than their own target language, thus using what could be described as ‘support translation’. All these procedures problematise the issue of ‘original’ and ‘translation’. An escalator in the Moscow Underground,

Switchable multiple source power supply

Abstract: In a readily switchable multiple solar panel system, the individual solar panels are interconnected with a control or switching apparatus which allows the solar panels to be readily switched into various series, parallel, or series-parallel configurations. With a relay based switching apparatus, a relay is connected between a pair of solar panels, so that in a first state, the panels are in series where the total voltage is the sum of each individual panel's voltage. When the relay is switched to the second state, each solar panel is in parallel, where the total voltage is a single panel's voltage and the current is multiplied by the number of panels. Multiple panels can be connected in this manner, with a relay between each successive pair of panels. With each relay connected in a parallel arrangement, a simple control switch in series with the relay coils can control the panel switching. The coil of each relay can also be individually controlled. Other individual voltage sources than solar panels can similarly be connected through a switching system which provides selective configuration of the sources into series, parallel, or series-parallel arrangements.

Solid state liquid level sensor and pump controller

Abstract: A liquid level controller for a device having a liquid reservoir includes a control board and a reservoir assembly. The reservoir assembly is disposed within the reservoir and includes a liquid level sensor, which is electrically connected to the control circuit. The control board includes a control circuit and a pump. The control circuit has a control circuit and a resistive power supply to power the control circuit. The control circuit controls the pump in response to signals from the level sensor and includes a CMOS logic gate and a MOSFET transistor to switch the pump. The control circuit further includes a second resistive power supply connected to a relay which controls an alarm. The second power supply is activated by a transistor responsive to an alarm signal from the level sensor, and powers the relay only when the alarm signal is present.

Intrinsically safe fluid tank overfill protection system

Abstract: A tank level monitoring and alarm system comprises a passive level switch, a transmitter, a repeater, and a receiver. It provides easy installation, convenient calibration, and very low maintenance. A mechanical level switch for the specific vessel is installed. The contacts of the level switch are connected to the transmitter. When the switch is activated, the transmitter immediately broadcasts an alarm signal to the receiver. A relay output at the receiver is either opened or closed thus activating the alarm or other device attached to it. The relay output may also connect to a control apparatus, such as a signal transmitter to provide for remote operation of such devices as valves.