The statistical data introduced by the author coincide with data of other authors and con. Locating microprocessor based relays in the yard significantly improves overall. Microprocessorbased relays generally possess the ability to communicate, listen, decide, act, and remember, and many are designed for the harsh environmental conditions of installations similar to figure 3. In addition to customizing specific microprocessorbased relay capabilities, skilled integration.
Problems and solutions 335 periodicity once in 4 years only for electromechanical relays is established. Identify microprocessorbased relay elements interpret ac and dc relay schemes install, connect and utilize opensource and proprietary communications software to set and test relays perform as foundleft tests and calibrate relays with the following functions ansi device numbers. Conventional polarization techniques using zerosequence voltage and current are implemented in nearly all microprocessor based relays. Conventional polarization techniques using zerosequence voltage and current are implemented in nearly all microprocessorbased relays. Basic concepts of microprocessors differences between. Measured values of variables are processed digitally by microprocessor. Pdf an electrical power system consists of generators, transformers, transmission and. They are functional replacements for electromechanical protective relays and may include many. Microprocessorbased distribution relay applications. As microprocessorbased relay technology approaches four decades, and companies. The unconditional statement about the greater reliability of semiconductor relays over electromechanical relays is a popular mistake 9.
Ability to combine a large number of protective and monitoring functions. The space requirement for the microprocessor based relay scheme is much less than the electromechanical relay scheme 5, 6. Microprocessor based relaying free download as powerpoint presentation. Microprocessorbased protective relays applications in. Many microprocessorbased relays now offer negativesequence current elements as a means of detecting ground faults and determining fault direction 4. Analysis of microprocessor based protective re lays mbpr. Fault locating has become a standard feature in nearly all microprocessor based relays. A new chapter on microprocessor applications to protection has been added. Also, microprocessor based relays can provide easy current magnitude and angle checks to ensure proper connections. Many microprocessor based relays now offer negativesequence current elements as a means of detecting ground faults and determining fault direction 4. This device involves the use of microcontroller for detection and isolation of. Understanding microprocessor based relay logic part 1. Reliability of microprocessorbased relay protection devices. Vladimir gurevich, israel electric corporation this first article in a twopart series examines four basic theses about the ostensibly high reliability of microprocessor based relay protection mp touted by supporters of mp.
Chris is an electrical engineering technologist, a journeyman power system electrician, and a professional engineer. Microcontroller based protective relay testing system. The article is a continuation of a set of the authors previous publications about the reliability of the microprocessorbased protective devices. Typical electromechanical relay scheme panel layout. Dec 28, 2015 fundamentals of microprocessor based relays 1. In that era, the efforts were concentrated to obtain a very high speed fault clearance. Another important advantage of the microprocessor based relay is that a microprocessor unit can perform the retransmission operation of several systems. Schwartz, schweitzer engineering laboratories, inc. Vladimir gurevich, israel electric corporation this first article in a twopart series examines four basic theses about the ostensibly high reliability of microprocessorbased relay protection mp touted by supporters of mp. Present day microprocessor based protective relays barely resemble their early 1990s distant cousins. Protective relays are of three different technology eras, electro mechanical, electronic and microprocessor based electromechanical relays installed up to 1983 with a 30 year life expectancy electronic relays installed 1980 through 1995 with 15 to 20 year life expectancy. Microprocessor power relay electrical engineering stack. To reliably extract and deliver the information from each of the relays to the scada systems, a twotier microprocessorbased communications processor configuration is adopted 1. Semiconductor relays possess increased reliability only at very large number of switching.
Prior to joining aep, sudhakar has worked in protection. The improvement in enlargement of power system both in mass and difficulty has brought the requirement for quick and dependable relays to defend main apparatus and to preserve scheme steadiness. The program can handle the online calculations and make the decision accordingly. Technical research paper microcontroller based fault. Moreover they do not interfere with any electronic apparatus near the installation. Analysis of microprocessor based protective re lays. The aim of this research is to develop a device used to detect faults in the line and isolate the connected system or instrument connected to it. Dolezilek schweitzer engineering laboratories, inc. Beginning electrical engineering student here and had a basic question. Protective relays feature past, present, and future a. It has been suggested that this article be merged into protective relay. Reliability of microprocessorbased relays is higher than reliability of electronic nonmicroprocessor devices. The experience thus gained has served as the basis for designing modern numerical protection and control equipment which can ensure more efficient and reliable operation.
Microprocessorbased overcurrent relays article pdf available in ieee transactions on industrial electronics ie331. Microprocessor based relays offer many other features that electromechanical relays do not offer such as fault locating, event reporting, advanced metering functions and control capability. Relay scheme design using microprocessor relays a supplement to relay trip circuit design by ieee psrc 1999 5 failures to operate. In largescale power transmission network, communication among a control center and these protective devices is necessary and it can be achieved by agent technology. Microprocessor based relays generally possess the ability to communicate, listen, decide, act, and remember, and many are designed for the harsh environmental conditions of installations similar to figure 3. Reliability of microprocessorbased relay protection. If x is greater than xl but less than x2 it sends the tripping signal after a predetermined delay. Microprocessorbased protective relays deliver more. The pr512 microprocessor based protection relays ensure correct operation and are immune to unwarranted trips, even in the presence of interference caused by electronic apparatus, by stormy weather conditions or electric discharges.
Abstract microprocessor based protective relays have been widely used to. This is a recreation of the first paper i ever presented from the neta conference in 2001 that was the foundation of the relay testing handbook series. Microprocessor based distance relays 19 reactance for the first zone of protection. If the capacitor switches are open and the capacitor control is in manual, close the. Fuses are single phase protective devices that combine sensing and interrupting. Fault locating has become a standard feature in nearly all microprocessorbased relays. Such relays are also termed as microprocessor type protective relays. The following are the characteristics of agent technology autonomy, cooperation, intelligence and adaptation. Microprocessorbased relay testing, distributionindustrial. He is also the author of the relay testing handbook series and founder of valence electrical training services. Microcontroller based overcurrent relay and directional. New developments in commercial relay manufacture are also included. Microprocessorbased relays offer many other features that electromechanical relays do not offer such as fault locating, event reporting, advanced metering functions and control capability.
A digital protective relay may also be called a numeric protective relay. Microprocessor relay capabilities improve protection, scada. Nov 11, 20 this is a recreation of the first paper i ever presented from the neta conference in 2001 that was the foundation of the relay testing handbook series. Locating microprocessorbased relays in the yard significantly improves overall.
Medium voltage products pr512 microprocessorbased self. Microprocessor relay capabilities improve protection. Microprocessor based protective relays deliver more information and superior reliability with lower maintenance costs richard d. Ability to combine a large number of protective and monitoring functions in a single. Digital energy the ge multilin ddfr is a power system fault recorder that collects, archives and manages disturbance and fault information that is recorded by microprocessor based protective relays distributed throughout your local power system. Microcontroller based relays, which avoid most of these. I am researching microprocessor based relays and came upon the sel351 relay for differential over current. Description the powerlogic digital relay figure 1 is a multifunction, microprocessor based device which performs these functions.
As microprocessor technology tends to be more mature, in the 1960s a microprocessorbased relay was brought about. Innovative distribution feeder protection and control schemes. Microprocessor based relays are prefer able because several types of characteristics can be an overcurrent relay algorithm normally includes a implemented in the same hardware or with a minimum digital filter to extract the fundamentalfrequency com change of hardware 1,2. Overcurrent relays, undercurrent relays, frequency relays, ground fault relays, directional ground fault relays. Technical research paper microcontroller based fault detector general abstract purpose. The microcomputer sends a tripping signal instantaneously if the measured value of x is less than xi.
Understanding microprocessor relay logic basic digital. Looking at the spec sheet, it shows the following functional overview. For example, an overcurrent relay may be required to use data of three phase currents and the residual current. This 8085 kit based interface circuit controls 64 relays. These new relays would quickly be established as the wave of the future. Microprocessorbased distance relays 19 reactance for the first zone of protection. Microcomputer a computer with a microprocessor as its cpu. Thus various advantages of microprocessor based relay are.
Compared to other analog and digital relays,the programmable microprocessor based relays have following superior features 1. It incorporates the latest developments in semiconductor technology and its applications to power system protection. Electromechanical and static relays were used in the beginning which had several drawbacks such as high burden on instrument transformers, long operating time, contact problems, inflexibility, inadaptability to changing system conditions, complexity and cost etc. The protective relays that may be tested by our developed relay testing system are. Development of protective relaying equipment in substations. Microprocessor based relays are computers with preset programming using inputs from the. Microprocessorbased transformer differential relays can make the delta internally.
The digital protective relay is a protective relay that uses a microprocessor to analyze power system voltages, currents or other process quantities for the purpose of detection of faults in an electric power system or industrial process system. Innovative distribution feeder protection and control schemes using new capabilities of microprocessor relays established by the various utility services and departments. Reliability of microprocessor based relays is higher than reliability of electronic non microprocessor devices. Another important advantage of the microprocessorbased relay is that a microprocessor unit can perform the retransmission operation of several systems. Therefore, you can connect the cts in wye on both sides of the bank, regardless of the transformer bank connection. Microprocessor based transformer differential relays can make the delta internally. Innovative distribution feeder protection and control. Nov 08, 20 this is a recreation of the first paper i ever presented from the neta conference in 2001 that was the foundation of the relay testing handbook series. For instance, in some time over current solid state relays, the incoming ac current is first converted into a small.
A digital relay is required to receive one or more power systems operational parameters. Different techniques and algorithms were proposed for achieving this objective. The book is a thoroughly revised and updated second edition of a successful text. High level of flexibility various protective functions can be. Proper testing of these protective relays ensures the integrity of the protection scheme, prevents nuisance. In some solid state relays, a simple microprocessor does some of the relay logic, but the logic is fixed and simple. Understanding microprocessor based relay logic part 2. It is quickest to need readjustment or even replacement as system changes. Multiprocessor relays allow for 86 lockout relay functions to be moved into the relay logic, reducing the number of components in the system. Fundamentals of microprocessor based protective relays suhag patel, p.
Tests of microprocessorbased relay protection devices. But the first microprocessor based relays offered as commercial devices was only in 1979 sachdev, 1979. The space requirement for the microprocessorbased relay scheme is much less than the electromechanical relay scheme 5, 6. Reliability of microprocessor based relay protection devices myths and reality part i by dr. Revised edition released june 2009 previously presented at the distributech conference, february 2007 previous revised edition released february 2008. Microprocessorbased transmission line relay applications. From the viewpoint of reliability, a statistical study between 2000 and 2009, posted by a. These requirements are based on various operational practices, engineering solutions and field experience. To reliably extract and deliver the information from each of the relays to the scada systems, a twotier microprocessor based communications processor configuration is adopted 1. Reliability of microprocessorbased relay protection devices myths and reality part i by dr. Complete monitoring of a relay and the associated relay scheme helps to reduce maintenance costs because the time between routine maintenance can be extended. Also, microprocessorbased relays can provide easy current magnitude and angle checks to ensure proper connections. Abstract transmission lines and equipments are protected with overcurrent relaying which is simplest and cheapest, yet most difficult to apply. Impedance calculation algorithm for microprocessor based.