The electromechanical and static relays are hard wired relays. Introduction digital computers in power system simulations, system view point, hierarchy of transmission and distribution system, nature and scope of power system studies. Adaptive in terms of dynamic relay settings and characteristics. Digital numerical relays provide a front panel display, or display on a terminal through a communication interface. There may be some typical condition during fault for which some relays should not be operated or operated after some definite time delay hence protection relay must be sufficiently capable to select appropriate condition for which it would be operated. Working principle of over current relayin an over current relay, there would be essentially a. By the mid1990s the solid state and electromechanical relay had been mostly replaced by digital relay in new construction. Electromechanical relay makes use of mechanical comparison devices, which cause the main reason. The timeline of the development of protective relays is shown below 1900 to 1963 1963 to 1972 1972 to 1980 1980 to 1990 electromechanical relay.
It blends a modern, intuitive interface with robust numerical algorithms to produce unparalleled levels of. About 6% of these are relays, 1% are wall switches, and 5% are remote control switches. Currently, the industry is introducing digitalnumerical relays as they provide substation protection, control and communication, and the recording of disturbances and faults. Power electronic control in electrical systems by e.
Over current relay working principle types electrical4u. Internal processing time of the designed 3phase system is 1820 ns. Comparison of protection relay types electrical engineering portal. Study and analysis of modern numerical relay compared to.
These terms or parameters are not so used in numerical relays but they are conceptually used and incorporated in numerical relays too but the way of their implementation is quite different than that of electromechanical relays. It incorporates the latest developments in semiconductor technology and its applications to power system protection. Power system protection in electrical power engineering aims at eliminating a faulted part in an. Types and revolution of electrical relays electrical notes. In distribution applications, the replacement by the digital relay proceeded a bit more slowly. The problem of relay power supply circuits and their various aspects. Established in the year 2001, rao electromechanical relays pvt. A big difference between conventional electromechanical and static relays is how the relays are wired. The analog measured values of current and voltage are.
They use microcontroller with a software based protection algorithm for the electrical fault detection. Electromechanical and static relays have fixed wiring and the setting is manual. Rao, digital relay numerical relays, tata mcgraw hill, new delhi, 1989 4. Testing and maintenance of protective gear, protection against surgesurge absorber, surgediverter. Implemented in low cost fpgacyclone iv with communication abilities. This portion of our website covers almost everything related to protection system in power system including standard lead and device numbers, mode of connections at terminal strips, color codes in multicore cables, dos and donts in execution. Numerical distance protection relay commissioning and.
Digitalnumerical relays addresses the urgent based need of manufacturers and users adopting this latest technology. The solid state relay static relay overview idc technologies. Digital relays for smart grid protection francesco muzi department of industrial and information engineering and economics university of laquila monteluco di roio, laquila 67100 italy francesco. This comparison summarize characteristics of all protection relay. Few of the differences between conventional electromechanical and solid state digital numerical relays can be highlighted as below. Equal area criterion, numerical integration methods. Computations of relay settings and development of programmable scheme logic for a numerical distance relay international journal of advanced technology and innovative research volume. Attracted armature solid computerized state digital relays plunger type magnetic induction. Design of a numerical adaptive relay based on memory. Our company is specialized in research, development and mass production of electromagnetic relays.
The book is a thoroughly revised and updated second edition of a successful text. Logic circuits or microprocessors compare the phase relationships of the square waves to make a trip decision. Transformers two winding and autotransformers, tap changing transformer and loads. Evaluation of dsp based numerical relay for overcurrent.
Presented at the 1998 international conference modern trends in the protection schemes of electric power apparatus and systems new delhi, india october 2830, 1998. Browse over 30,000 products, including electronic components, computer products, electronic kits and projects, robotics, power supplies and more. In digital relay microprocessors and micro controllers are used in replacement of analogue circuits used in static relays to implement relay functions. A wide variety of digital control relay switch options are available to you, such as usage, contact load, and size. The term static implies that the relay has no moving mechanical parts in it. The numerical distance protection relay used is rel 5112.
Introduction and architecture of numerical relay electrical. Nov 20, 2016 plug setting multiplier and time setting multiplier are used only for electromechanical relays. Digital relays sometimes called microprocessorbased or numerical relays can more precisely and economically manage system protection, coordination and communication as compared to traditional analog electricalmechanical relays. The distinction between digital and numerical relay rests on points of fine technical detail.
Electro mechanical vs numerical relay linkedin slideshare. Handbook of switchgear bhel digitalnumerical relays t. Numerical relays are equipped with software to communicate with external device to program to relay. Numerical relays also help in reducing burden voltamperes of current transformer ct and voltage transformer vt. New developments in commercial relay manufacture are also included. Numerical relays are the product of the advances in technology from digital relays. We try also to foresee the future prospects and trends in this area. Generally, there are several different types of numerical protection relays. Digitalnumerical relays provide a front panel display, or display on a terminal through a communication interface. Pdf modeling and testing of a digital differential relay. The distinction between digital and numerical protection relay rests on points of fine technical detail, and is rarely found in areas other than protection. Isolation voltage is another area where electromechanical relays are limited. The resulting protective relay has higher processing capability making it more able to handle parallel multichannel sources than existing digital numerical relays are. Introduction to digital and numerical relays, microcontrollermicroprocessor based current.
In digital relays measured ac quantities are manipulated in analogue form and subsequently converted into squarewave binary voltages. Electromechanical relay makes use of mechanical comparison devices, which cause the main reason for the bulky size of relays. The characteristics and behavior of the numerical relays can be programmed. Numerical relays are also called as programmable relays. Aug 29, 2018 the relay must be operated in only those conditions for which relays are commissioned in the electrical power system.
The relay settings will be automatically adjusted with the changes of power system parameters with. Applications of digital and analog computers to power system protection microprocessor applications including the peripheral equipment for relay applications. Microcontroller based overcurrent relay and directional. The processing of numerical relays using dsp is also optimized for realtime signal processing applications 1. Besides covering the current developments, the book also covers current research as well as commercial application of digitalnumerical relays. The protective relay industry has kept pace with the technological advancements in the field. Static relay digital relay numerical relay 1925single disc type relay single input 1963static relay all purpose 1980digital type relay all purpose 1990numerical type relay all purpose. The fundamental objective of system protection is to quickly isolate a problem so that the unaffected portions of a system can continue to function. This is used to display relay settings and realtime currentvoltage values, etc. The solid static relays use analogue electronic devices instead of magnetic coils and mechanical components to create. A busbar protection relay serves as a traditional rtu casper labuschagne, schweitzer engineering laboratories, inc. More complex digital relays will have metering and communication protocol ports, allowing the relay to become an element in a scada system. Mohammed tawfeeq overcurrent protective relays overcurrent relays overcurrent relaying is the simplest and cheapest type of protection used for protection of lines, transformers, generators and motor. Potential candidate for an adaptive ocr in smart grid applications.
With this uptodate coverage, this book is indispensable to engineers in the relay. Back to back hvdc transmission, induction heating, electronic. Apr 25, 2018 digital output contacts of numerical relays are used for wiring with the auxiliary relays to extend tripping command to the circuit breaker. Numerical relays protection and control products for power. Tension controlled contacts core sensing coil electro mechanical start of century 2.
Tsm rao, power system protection static relays, tata mcgraw hill. As a result, the relay is capable of performing complex digital signal processing to detect fault faster and more accurately compared to previous relay technology. Basler electric be127 solid state protective relay, overunder voltage jiguparmar the solid state relay static relay overview history of relay the static relay is the next generation relay after electromechanical type. It also covers principles of various power system protection relays and schemes including special power system protection schemes like differential. Therefore, the use of numerical relays will soon replace previous relays technology such as digital relays, static relays or even electromechanical relays 4. These are also called digital relay, computerbased relay or microprocessorbased relay. These relays are used a great deal when the source impedance is large compared to that of the power system element being protected, when fault levels at the relay position are similar to those at the end of the protected element 1. By simple calculation for ht side current of 52 amp, 3 core, 25 sq mm cable will suffice. Numerical relays numerical over current relay with. Design of modern numerical relay equipment free ebook download as powerpoint presentation. Dear sir, what is the size of 3core,11kv cable required for kva, 11.
However, such technology will be completely superseded within the. While the authors of 567 employed matlab simulink, to model and tested, a digital differential relay, with a dual slope, dedicated a threephase transformers protection. Liew department of electrical engineering, ivational unmersrty of singapore, 10 kent ridge cresccn, singapore 119260. Plug setting multiplier and time setting multiplier are used only for electromechanical relays. Protective relays serve as a backbone to the power system. A new chapter on microprocessor applications to protection has been added. Mohamad tawfeeq types of relays the main types of protective relays are summaries in the following diagram.
Keywordselectromechanical relay, numerical relay, local breaker backup, bus bar protection, goose. Zocholl and gabriel benmouyal schweitzer engineering laboratories, inc. Implementation of solid state relays for power system. Numerical relays are based on the use of microprocessors. As a result, the reliability of the relay also increases.
Design and implementation of flexible numerical overcurrent. Numerical relays are equipped with software to communicate with external device to program to relay or one can program by navigating through the relay menu. The solid static relays was first introduced in 1960s. The solid state relay static relay overview on photo. Types and revolution of electrical relays electrical.
Numerical distance protection relay commissioning and testing. Dec 24, 2012 however, such technology will be completely superseded within the next five years by numerical relays. How microprocessor relays respond to harmonics, saturation, and other wave distortions stanley e. Digital output contacts of numerical relays are used for wiring with the auxiliary relays to extend tripping command to the circuit breaker. Over current relay, impedance relay, reactance relay, mho relay, microprocessor based distance relaying. It has seen ten generations of refinement since its release in 1982. Their setting can be manually changed but their wiring is fixed. Here, a case study relating to both electromechanical relay and numerical relay will be done and the results are analyzed. The static relay is the next generation relay after electromechanical type. Rao and has been published by tata mcgrawhill education this book supported file pdf, txt, epub, kindle and other format this book has been release on 20050701 with electric power systems categories. Presentation on numerical relays free download as powerpoint presentation. Basic relay concepts electromechanical static digital numerical pre 1970s 1970s 1980s present 8. Pdf ee6702 protection and switchgear ps books, lecture. Abstract this work describes the design of a dsp digital signal processor based adaptive numerical mho relay, to be used for distance protection schemes of long distance transmission lines.
An electromagnetic relay is a switch that is turned on and off by a magnetic field. Testing and maintenance of static relays references. Modeling and evaluation of protective relays for power systems. Numerical relays numerical relays or digital relays are designed to carry out protection function of various electrical equipments such as generator, transformer, transmission lines, motor etc. Introduction protective relaying is an integral part of any electrical power system. Dsp based numerical relay for overcurrent protection ijert. New simulink libraries for modeling digital protective.
Electric power systems research 38 1996 11 i7 microcontroller based overcurrent relay and directional overcurrent relay with ground fault protection zhijun gan, s. Rao, solid state protective relaying, tata mcgraw hill. There is only one current operated element in the relay, no voltage coil etc. Implementation of solid state relays for power system protection. Over load current setting is 125%, plug setting of relay is 0. Ann based flexible numerical overcurrent relay ocr. Numerical over current relay with communication jnc 068 c. A century old protection technique has recently transformed itself into fourth generation technology, a massive development from i electromechanical to static, ii static to digital and from iii digital to numerical and wide area protection. It is very easy to provide electrical isolation between the coil that creates the magnetic field and the switch contacts. The relays, which are associated with microprocessor and work on numbers representing instantaneous values of the signals such that current, voltage, frequency and power factor etc. Numerical relays are essentially small computers the intelligent electronic device. Sep 01, 2018 in an over current relay or oc relay the actuating quantity is only current. Me reference books electric power system distributed generation.
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