Dec 28, 2015 fundamentals of microprocessor based relays 1. These new relays would quickly be established as the wave of the future. Microprocessor based relaying free download as powerpoint presentation. Different techniques and algorithms were proposed for achieving this objective. Analysis of microprocessor based protective re lays. Also, microprocessorbased relays can provide easy current magnitude and angle checks to ensure proper connections. Electromechanical relay makes use of mechanical comparison devices, which cause the main reason for the bulky size of relays. Impedance calculation algorithm for microprocessor based.
Understanding microprocessor relay logic basic digital. From the viewpoint of reliability, a statistical study between 2000 and 2009, posted by a. The following are the characteristics of agent technology autonomy, cooperation, intelligence and adaptation. Fault locating has become a standard feature in nearly all microprocessorbased relays. The protective relays that may be tested by our developed relay testing system are. Development of protective relaying equipment in substations. Multiprocessor relays allow for 86 lockout relay functions to be moved into the relay logic, reducing the number of components in the system. Revised edition released june 2009 previously presented at the distributech conference, february 2007 previous revised edition released february 2008. Microprocessor based distance relays 19 reactance for the first zone of protection.
The book is a thoroughly revised and updated second edition of a successful text. 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. Conventional polarization techniques using zerosequence voltage and current are implemented in nearly all microprocessor based relays. I am researching microprocessor based relays and came upon the sel351 relay for differential over current. In that era, the efforts were concentrated to obtain a very high speed fault clearance. High level of flexibility various protective functions can be. For instance, in some time over current solid state relays, the incoming ac current is first converted into a small. Proper testing of these protective relays ensures the integrity of the protection scheme, prevents nuisance. Reliability of microprocessorbased relays is higher than reliability of electronic nonmicroprocessor devices.
Microprocessor relay capabilities improve protection. Innovative distribution feeder protection and control. The article is a continuation of a set of the authors previous publications about the reliability of the microprocessorbased protective devices. Microcontroller based relays, which avoid most of these. 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. Another important advantage of the microprocessorbased relay is that a microprocessor unit can perform the retransmission operation of several systems. 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. Therefore, you can connect the cts in wye on both sides of the bank, regardless of the transformer bank connection. Typical electromechanical relay scheme panel layout. Another important advantage of the microprocessor based relay is that a microprocessor unit can perform the retransmission operation of several systems. A digital protective relay may also be called a numeric protective relay.
Microprocessor relay capabilities improve protection, scada. It incorporates the latest developments in semiconductor technology and its applications to power system protection. 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. The pr512 microprocessorbased 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. If x is greater than xl but less than x2 it sends the tripping signal after a predetermined delay. 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. A digital relay is required to receive one or more power systems operational parameters. In utility and industrial electric power transmission and distribution systems, a digital protective relay is a computerbased system with softwarebased protection algorithms for the detection of electrical faults. Microprocessorbased protective relays applications in. Measured values of variables are processed digitally by microprocessor. Microprocessor based relays are computers with preset programming using inputs from the. Abstract transmission lines and equipments are protected with overcurrent relaying which is simplest and cheapest, yet most difficult to apply. 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. Such relays are also termed as microprocessor type protective relays.
Microprocessor based transformer differential relays can make the delta internally. Complete monitoring of a relay and the associated relay scheme helps to reduce maintenance costs because the time between routine maintenance can be extended. Dolezilek schweitzer engineering laboratories, inc. The statistical data introduced by the author coincide with data of other authors and con. Analysis of microprocessor based protective re lays mbpr. Reliability of microprocessor based relay protection devices myths and reality part i by dr. 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. Microprocessorbased relay testing, distributionindustrial. Microprocessor power relay electrical engineering stack. This 8085 kit based interface circuit controls 64 relays. Microprocessorbased transformer differential relays can make the delta internally. Present day microprocessorbased protective relays barely resemble their early 1990s distant cousins. Prior to joining aep, sudhakar has worked in protection. Reliability of microprocessorbased relay protection.
Reliability of microprocessor based relays is higher than reliability of electronic non microprocessor devices. Semiconductor relays possess increased reliability only at very large number of switching. A new chapter on microprocessor applications to protection has been added. Reliability of microprocessorbased relay protection devices. Fault locating has become a standard feature in nearly all microprocessor based relays. Technical research paper microcontroller based fault detector general abstract purpose.
Microcontroller based overcurrent relay and directional. 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. The program can handle the online calculations and make the decision accordingly. Innovative distribution feeder protection and control schemes using new capabilities of microprocessor relays established by the various utility services and departments. Pdf an electrical power system consists of generators, transformers, transmission and. But in reality it was just the tip of the iceberg so to speak. 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. Fundamentals of microprocessor based protective relays suhag patel, p. Conventional polarization techniques using zerosequence voltage and current are implemented in nearly all microprocessorbased relays. Overcurrent relays, undercurrent relays, frequency relays, ground fault relays, directional ground fault relays. 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. Compared to other analog and digital relays,the programmable microprocessor based relays have following superior features 1.
Medium voltage products pr512 microprocessorbased self. 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. They are functional replacements for electromechanical protective relays and may include many. Problems and solutions 335 periodicity once in 4 years only for electromechanical relays is established. 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. Understanding microprocessor based relay logic part 2. Beginning electrical engineering student here and had a basic question. He is also the author of the relay testing handbook series and founder of valence electrical training services. 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. Ability to combine a large number of protective and monitoring functions in a single. Microprocessorbased relays offer many other features that electromechanical relays do not offer such as fault locating, event reporting, advanced metering functions and control capability. Looking at the spec sheet, it shows the following functional overview. Locating microprocessor based relays in the yard significantly improves overall.
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. The space requirement for the microprocessorbased relay scheme is much less than the electromechanical relay scheme 5, 6. Schwartz, schweitzer engineering laboratories, inc. But the first microprocessor based relays offered as commercial devices was only in 1979 sachdev, 1979. 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. Reliability of microprocessorbased relay protection devices myths and reality part i by dr.
It has been suggested that this article be merged into protective relay. Innovative distribution feeder protection and control schemes. Relay scheme design using microprocessor relays a supplement to relay trip circuit design by ieee psrc 1999 5 failures to operate. Ability to combine a large number of protective and monitoring functions. Locating microprocessorbased relays in the yard significantly improves overall.
Abstract microprocessor based protective relays have been widely used to. Moreover they do not interfere with any electronic apparatus near the installation. Microprocessorbased protective relays deliver more. Microcomputer a computer with a microprocessor as its cpu. It is quickest to need readjustment or even replacement as system changes. Many microprocessor based relays now offer negativesequence current elements as a means of detecting ground faults and determining fault direction 4. 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. Protective relays feature past, present, and future a. In addition to customizing specific microprocessorbased relay capabilities, skilled integration. 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. Microprocessorbased transmission line relay applications. In some solid state relays, a simple microprocessor does some of the relay logic, but the logic is fixed and simple.
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. Many microprocessorbased relays now offer negativesequence current elements as a means of detecting ground faults and determining fault direction 4. Understanding microprocessor based relay logic part 1. 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. If the capacitor switches are open and the capacitor control is in manual, close the. As microprocessorbased relay technology approaches four decades, and companies. Also, microprocessor based relays can provide easy current magnitude and angle checks to ensure proper connections. Microprocessorbased distribution relay applications. Technical research paper microcontroller based fault. For example, an overcurrent relay may be required to use data of three phase currents and the residual current. This device involves the use of microcontroller for detection and isolation of. Basic concepts of microprocessors differences between. The unconditional statement about the greater reliability of semiconductor relays over electromechanical relays is a popular mistake 9.
Microprocessorbased overcurrent relays article pdf available in ieee transactions on industrial electronics ie331. As microprocessor technology tends to be more mature, in the 1960s a microprocessorbased relay was brought about. Thus various advantages of microprocessor based relay are. The useful life of microprocessorbased relays schweitzer. In largescale power transmission network, communication among a control center and these protective devices is necessary and it can be achieved by agent technology. Fuses are single phase protective devices that combine sensing and interrupting. Tests of microprocessorbased relay protection devices. Present day microprocessor based protective relays barely resemble their early 1990s distant cousins. Description the powerlogic digital relay figure 1 is a multifunction, microprocessor based device which performs these functions. Chris is an electrical engineering technologist, a journeyman power system electrician, and a professional engineer. Microprocessorbased distance relays 19 reactance for the first zone of protection. Microcontroller based protective relay testing system. 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. New developments in commercial relay manufacture are also included.
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