This 8085 kit based interface circuit controls 64 relays. Microprocessor based relays, also called digital relays, have a proven track record of reliability, with over 100,000 relayyears of field experience. One can deduce that the execution order plays a significant role when designing logic in relays that provide multiple functions in a single relay. The functions of electromechanical protection systems are now being replaced by microprocessorbased digital protective relays, sometimes. Microprocessor based relays, also called digital relays, have a proven track record of reliability, with over 100,000 relay years of field experience. 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. Failure rate of a protective relays of various kinds. Microprocessor based over current relay current is taken from c. This paper evaluates the performance of a transmission line protection scheme using microprocessor based protective and electromechanical relays using discrete components.
Integral to microprocessor based relay tc2 cc in1 breaker status input in2 trip circuit monitor input optional. Microprocessorbased distribution relays contribute to improved reliability and reduced costs on electric power systems. Transmission and distribution reliability of microprocessor. Such relays are also termed as microprocessor type protective relays. Commissioning microprocessor based ied communication systems. They are functional replacements for electromechanical. Analysis of microprocessor based protective re lays mbpr. In bus, transformer, or generator protection, this is accomplished naturally by using a single protective device that directly receives all the required currents and samples them in a synchronized fashion. Revised edition released november 2008 previously presented at the 58th annual georgia tech protective relaying conference, april 2004, and 57th annual conference for protective relay engineers, march 2004. Abstractthis report covers issues concerning the security of electronic communication paths to protective relays. The question arises if the microprocessorbased protection device is a relay in the full sense of the. Pr512 microprocessorbased selfsupplied protection relays. Misapplication of microprocessor protective relays has the same impact on protection reliability as the. Protective relays feature past, present, and future a.
Schwartz, schweitzer engineering laboratories, inc. Mohamad tawfeeq types of relays the main types of protective relays are summaries in the following diagram. Now, microprocessorbased digital relays are becoming the norm for new installations and many replacements, because of their improved protective capabilities, reliability, and additional features. Introduction protective relays play a critical role in the operation of the electrical power system. In electrical engineering, a protective relay is a relay device designed to trip a circuit breaker when a fault is detected 4 the first protective relays were electromagnetic devices, relying on coils operating on moving parts to provide detection of abnormal operating conditions such as overcurrent, overvoltage, reverse power flow, overfrequency, and underfrequency. The micro51 operates from conventional 5a or 1a secondary current transformers. Introduction protective relays evolved from singlefunction electromechanical devices, through singlefunction or integrated static devices into a. Digital relays are the functional replacements for electromechanical protective relays and may include many protection functions in a single unit, as well as providing metering, communication, and selftest. But in reality it was just the tip of the iceberg so to speak. Microprocessor relays are computerbased systems that utilize softwarebased protection algorithms for the detection of electrical faults. Protective relays are designed to take action when abnormal. Microprocessor based overcurrent relay polytechnic hub.
Numerical relays are based on the use of microprocessors. Numerical relays protection and control products for. In case of line protection via distance protection schemes, microprocessor based relays also provide over current protection, directional over current protection for selectivity. Data verified includes, but is not limited to that of scenario a, but also, alarms, control, status, events, reports.
They, in turn, inherit some of the computer relays functions. This paper presents a general hardware scheme for testing protective relays using microprocessor based systems. Microprocessor relays with logic and communication capabilities can accomplish this type of scheme by using either hardwired trip contacts or by using communication signals between each other to transfer statuses. Numerical settings this is a basic configuration level available in any generation of protective relays. In short, a phase comparator compares two input quantities in phase angle vertically irrespective of the magnitude and operates if the phase angle between them is microprocessor based protective relays may provide a considerable. In digital relay microprocessors and micro controllers are used in replacement of analogue circuits used in static relays to implement relay functions. The statistical data introduced by the author coincide with data of other authors and con. Digital relays are the functional replacements for electromechanical protective relays and may include many protection functions in a single unit, as well as providing metering, communication, and. Protective relays and trip units the term switchgear is used to describe coordinated devices used for control and protection of equipment such as generators, transformers, capacitor banks, motors, and distribution lines. These new relays would quickly be established as the wave of the future.
A big difference between conventional electromechanical and static relays is how the relays are wired. As the service life of these devices exceeds multiple decades, questions regarding when and how to strategically replace these relays are increasing. Siprotec microprocessor based protective relay history of protective relay. Problems and solutions 335 periodicity once in 4 years only for electromechanical relays is established. Understanding microprocessor based relay logic part 1. They are considered as a complete protection package in a single unit. Microprocessorbased protection devices, relay protection, reliabi lity, ad converter, central processor. Microprocessorbased protective relays applications in nigeria. Tutorial on operating characteristics of microprocessorbased. Microcontroller based protective relay testing system. Tests of microprocessorbased relay protection devices. Electric utilities company of nigeria eucn have traditionally used electromechanical emr distance relays for the protection of transmission lines in the past. Attracted armature solid computerized state digital relays plunger type magnetic induction.
Power system, microprocessor based relays, electromechanical relays, engineering design, maintenances costs, protection schemes. Microprocessorbased distribution relay applications. Microprocessor relays are computer based systems that utilize software based protection algorithms for the detection of electrical faults. This transition from the electromechanical to the numerical relays can be justified by the large flexibility and the wonderful features such as. We have designed and implemented microprocessor based relay testing system through the use of the new technologies such as microcontroller. Inspections and checks for microprocessorbased relays. Microprocessor based distribution relays contribute to improved reliability and reduced costs on electric power systems. Modern microprocessorbased relays allow for much better protection schemes to protect the distribution substation assets. A fully integrated ied equipped substation with 25 breakers testing the full complement of data displayed on a local monitoring system and rtu. The protective relays that may be tested by our developed relay testing system are. Rebirth of negativesequence quantities in protective.
However, during the past 1520 years, there has been a widespread displacement of emr by microprocessorbased relay protection devices gurevich, 2012. This is either programmable or fixed based on the relay. Microprocessorbased protective relays deliver more information and superior reliability with lower maintenance costs richard d. The article is a continuation of a set of the authors previous publications about the reliability of the microprocessorbased protective devices. The hardware and software commonality across the eseries family platform makes it easy for users to program. Microprocessor based relays using the differential principle need current data to have the same time reference. Typical examples include overcurrent pickup level, distance reach, zerosequence. Users have become accustomed to the electromechanical relays ability to last 50 plus years and this has strained the expectations of microprocessor based relays. Structure of the microprocessorbased system m3430 type beckwith electric co.
The source concept considerations in a protective relay. Thus various advantages of microprocessor based relay are. Microprocessorbased protective relays deliver more. The program can handle the online calculations and make the decision accordingly. Microprocessorbased protective relays applications in. It is the goal of this paper to present the reader with some background material and discussions by which they can. Reliability of microprocessorbased relay protection. For the most effective protection, many utilities and industrial facilities are replacing aging electromechanical relays with new generation microprocessorbased. With the advent of more and more powerful microprocessors and the development of analytical algorithms, microprocessor based protective relays may provide a considerable. Microprocessor relays are computer based and use programmable logic. Now, microprocessor based digital relays are becoming the norm for new installations and many replacements, because of their improved protective capabilities, reliability, and additional features. Sleva pdf, epub ebook d0wnl0ad improve failure detection and optimize protection in the everevolving field of protective relay technology, an engineers personal preference and professional judgment are as important to power system protection as the physical relays used to detect and isolate abnormal. For example, if a fault is detected, the protective relay will respond by tripping and potentially locking out a breaker. Another important advantage of the microprocessorbased relay is that a microprocessor unit can perform the retransmission operation of several systems.
In the event of a fault, protective relays protect electrical systems, equipment, and people from serious damage and injury. Another important advantage of the microprocessor based relay is that a microprocessor unit can perform the retransmission operation of several systems. When microprocessor relays began to be applied in the. Tutorial on operating characteristics of microprocessor. Operation and maintenance of protective relays and associated. Conventional relays like electromechanical relays employed bulky sized mechanical comparators which reduced their speed and these relays often served a single function and a single characteristic. Hence domestic and industrial facilities are increasingly investing in microprocessorbased relays to. Microsoft powerpoint relay scheme design using microprocessor relays. Microprocessorbased relays create phasors from sinusoid waveform input relay word bits control relay io microprocessorbased relays offer many troubleshooting and fault analysis tools selogic control equations provide programming flexibility to create virtual control circuits. A microprocessorbased scheme for testing protective relays. Quantities in protective relaying with microprocessorbased relays fernando calero schweitzer engineering laboratories, inc.
Though this relay has a microprocessor, it lacks the attributes of a digitalnumeric relay, and hence the term microprocessor. It also covers power system, transformer protection and zone of protection. Numerical relays protection and control products for power. Microprocessor based protective relays are developed on the basis of early computer relaying devices. Microprocessor based overcurrent relays article pdf available in ieee transactions on industrial electronics ie331. For microprocessor based relays, the cycle time is how frequently a function is performed or executed. Introduction as microprocessorbased relay technology approaches four decades, and com panies have devices in service that are several decades old, the following questions start to arise. Protective relay principles focuses on probable power system failure modes and the important characteristics of the protective relays used to detect these postulated failures. Microprocessorbased relays using the differential principle need current data to have the same time reference. The myth of complexity configuration mechanisms of modern microprocessorbased protective relays page 3 of 12 2.
Dec 24, 2012 compared to static relays, digital relays introduce analogue to digital convertor ad conversion of all measured analogue quantities and use a microprocessor to implement the protection algorithm. 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. By using the boolean simplification, we can represent the logic in a microprocessor based relay in a few different ways. Sep 07, 2015 protective relay principles by anthony f.
Then a relatively simple microprocessor does a slow speed ad conversion of the dc signal, integrates the results to create the timeover current curve response, and trips when the integration rises above a set point. Life cycle considerations for microprocessor relays. Commissioning microprocessor based ied communication systems an65a00 6 b. Microprocessorbased relays, also called digital relays, have a proven track record of reliability, with over 100,000 relayyears of field experience.
Power system protection part power system protection lecture. In utility and industrial electric power transmission and distribution systems, a digital protective relay is a computer based system with software based protection algorithms for the detection of electrical faults. The microprocessor may use some kind of counting technique, or use the discrete fourier transform dft to implement the algorithm. For the most effective protection, many utilities and industrial facilities are replacing aging electromechanical relays with new generation microprocessor based relays. Micro51 microprocessorbased overcurrent relays are used for phase and ground overcurrent protection in utility, industrial and commercial electrical power systems. Micro51 microprocessor based overcurrent relays are used for phase and ground overcurrent protection in utility, industrial and commercial electrical power systems. Most of todays microprocessor based relays implement multifunctional protection features. The pr512 relays are devices using digital microprocessor based technology to obtain data processing regarding the protection. Electromechanical and static relays have fixed wiring and the setting is manual. Structure of the microprocessor based system m3430 type beckwith electric co.
Siprotec 7sj61, 62, and 63 are microprocessor based protective relays designed to provide. Microprocessorbased overcurrent relays article pdf available in ieee transactions on industrial electronics ie331. Commissioning microprocessor based ied communication. Power system, microprocessorbased relays, electromechanical relays, engineering design, maintenances costs, protection schemes. Abstractconfidence in microprocessorbased protective relays has steadily increased over the four decades since their invention. Relay scheme design using microprocessor relays a report to the.
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