static and numerical relays

First generation numerical relays were mainly designed to meet the static relay protection characteristic, whereas modern numeric protection devices are capable of providing complete protection with added functions like control and monitoring. By organising the I/O on a set of plug-in printed circuit boards (PCBs), additional I/O up to the limits of the hardware  / software can be easily added. The distinction between digital and numerical relays is particular to Protection. If only one or two phases are lost, the VT failure algorithm can be accomplished. Typical functions that may be found in a numerical relay other than protection functions are described in this section. Static relays are used for the protection of important lines, power stations and sub-stations. This is perhaps the most obvious and simple function to implement, as it involves the least additional processor time. A numerical relay usually provides many more features than a relay using static or electromechanical technology. Software problems are minimized by rigorous use of software design techniques and the ability to download updated software. Numerical relays are natural developments of digital relays due to advances in technology. This relay has to be installed straight only and away from magnetic field. Learn about power engineering and HV/MV/LV substations. Gravitational force can affect the relay. ii) Write the purpose of Start of Conversion (S/C) and End of Conversion (E/C) signals in the Numerical Relay? He is member of Institution of Engineers (MIE), India. Its powerful six current sources (three-phase mode: up to 64 A / 860 VA per channel) with a great dynamic range, make the unit capable of testing even high-burden electromechanical relays with very high power demands. Supply is not required and all the Numerical Relay are Multi function relays. Similarly, the amount of data that must be recorded is much larger, requiring larger storage. please explain, Its very informative artical.thank you sir. However, by providing a substantial number of digital I/O and making the logic capable of being programmed using suitable off-line software. Different configurations may require different relay settings to maintain the desired level of network protection. A different interface port for the Hot signals (with varying voltages) for the E&M and Static Relays while as a different Communication port for the Soft signals from the Numerical Relays. Operating Principle: They use principle of electromagnetic principle. T. S. Madhava Rao. As with earlier generations of relays and according to market segmentation, manufacturers offer different versions, each with a different set of functions. The first protection devices based on microprocessors were employed in 1985. This comparison summarize characteristics of all protection relay types described in previously published technical articles: References: – Handbook of Switchgear – Bhel – Digital/Numerical Relays – T.S.M. The standard normally used is an IRIG-B or IEEE 1588 signal, which may be derived from several sources including a GPS satellite receiver. ), Auxiliary protection functions (broken conductor, negative sequence, etc. The memory can easily be expanded to allow storage of a greater time period of input data, both analogue and digital, plus the state of the relay outputs. Practical experience indicates that numerical relays are as reliable as relays of earlier technologies. In industrial and small distribution networks, this may be all that is required. Numerical relays are the latest development in this area. Any problems revealed by such tests require specialist equipment to resolve so it is simpler to replace a faulty relay and send it for repair. It incorporates the latest developments in semiconductor technology and its applications to power system protection. this portal is very helpful to all the electrical engineering student as well as professor and technical engineer.It’s very nice and helpful for all in electrical engineering to get practical knowledge & idea very easily. Overcurrent Relay Objective Type Questions and answers; 31. It consists of one or more digital signal processors, some memory, digital and analogue input/output (I/O), and a power supply. El. can you advice the indian componies? Figure 1, Figure 2 and Figure 3 show typical numerical relays, while Figure 4 and Figure 5 show typical numerical relay boards. B. Dear Jignesh A very well compiled work. The distinction between digital and numerical protection relay rests on points of fine technical detail, and is rarely found in areas other than Protection: Ch 7, pp 102. A big difference between conventional electromechanical and static relays is how the relays are wired. 20% off code for Pro Plan: EEP2020. The numerical relays are used for various types of protection and they are classified on the basis of characteristics, Logic, Actuation parameter and application. Therefore solid state relays are also called as static relays. It may be inconvenient to download the record immediately, so facilities may be provided to capture and store a number of disturbances. The typical architecture of a numerical relay is shown in Figure 6. Also numerical relays have functionality that previously required separate equipment. C. A transistor switch . Since our commencement in the year 1991, we, “Prok Devices Private Limited”, an ISO 9001:2008 certified company, are well-known in the industry as an eminent manufacturer, supplier and trader, engrossed in providing Electric Relay & Meter. One obvious development is the provision of RTU facilities in designated relays that act as local concentrators of information within the overall network automation scheme. The signals may be initially input to several simultaneous sample-and–hold circuits before multiplexing, or the time relationship between successive samples must be known if the phase relationship between signals is important. The digital signal processor (DSP) in a numerical relay normally can handle both the relay protection function calculations and general management of the relay such as HMI and I/O. Numerical relays perform many more functions than earlier generations of relays so testing them is more complex. If I define a Numerical Relay, honestly speaking it will seem to be quite tough but in reality they are very user friendly and easy to … However, if the DSP is overloaded it cannot complete the protection algorithm calculations in the required time and the protection function is slowed. The static relay is more costly as compared to the electromagnetic relay. They use one or more digital signal processors (DSP) optimised for real time signal processing, running the mathematical algorithms for the protection functions. There may be other advantages such as different logic schemes required by different utilities that no longer need separate relay versions, or some hard-wired logic to implement, and all of these reduce the cost of manufacture. Main Protection: Switched distance scheme (fed from bus PT). Such relays are also termed as microprocessor type protective relays. Figure 2 shows cost comparison of numerical relay with electromechanical and static relay [1]. The Essentials Of Numerical Relays, Their Features And Important Considerations, Electrical engineer, programmer and founder of, CB Control and State Indication / Condition Monitoring, CB Control/State Indication / Condition Monitoring, periodic maintenance of their operating mechanisms, Distance Protection – several schemes including user definable, Overcurrent Protection (directional/non-directional), Several Setting Groups for protection values, Measurement of Power System Quantities (Current, Voltage, etc. Relays detect and locate faults by measuring electrical quantities in the power system which are different during normal and intolerable conditions. The most common are relay comparators based on rectifier bridges, which can be arranged as either amplitude or phase comparators. Present generation relays. D. A differentiating circuit With the aid of suitable software held by a user, it may be possible to download the new software version instead of requiring a visit from a service engineer. Numerical relays are the product of the advances in technology from digital relays. The IEEE defines protective relays as: “relays whose function is to detect defective lines or apparatus or other power system conditions of an abnormal or dangerous nature and to initiate appropriate control circuit action ”. Additionally, the input signals must be amplitude limited to avoid them exceeding the measurement range, otherwise the waveform is clipped, introducing harmonics. The internal communications bus links the hardware and therefore is a critical component in the design. Over Current/ Earth Fault:When excessive current flows through a system it will trip the circuit br… low burden on the CT and VT, fast operation, absence of mechanical inertia and; contact trouble, long life and; less maintenance. Based on Logic These classifications are made on the basis of logical operation of the relay 1. Electromechanical Relays The above diagram shows the schematic of an electromechanical relay. Numerical Relays working explained in this post with the help of a Numerical relay used in industrial applications. This relay consists of two rectifier bridges and a moving coil or polarized moving iron relay. Unfortunately, power systems change their topology due to operational reasons on a regular basis, such as supply from normal or emergency generation. Therefore the functions previously carried out by separate devices such as bay controllers, discrete metering transducers and similar devices are now found in a protection relay. As CTs and VTs for protection functions may have a different accuracy specification to those for metering functions, such data may not be sufficiently accurate for tariff purposes. This may obviate the need for duplicate relays to be fitted with some form of switching arrangement of the inputs and outputs depending on network configuration. Incorrect results are then obtained. A numerical relay has the functionality that previously required several discrete relays, therefore the relay functions such as overcurrent or earth fault are referred to as ‘relay elements’. Working Principle of Over Current Relay. Tell us what you're thinking... we care about your opinion! The parts are as follows: Spring Electromagnet Mech. Rao) 2.why In comparison table relay resistance are different unit? The term ‘static’ implies that the relay has no … ), Consistency of operation times – reduced grading margin, Sequence quantities (positive, negative, zero), Max. A Electromechanical and static relays have fixed wiring and the setting is manual. Although there is an internal clock, this is of limited accuracy and use of this clock to provide time information may cause problems if the disturbance record has to be correlated with similar records from other sources to obtain a complete picture of an event. Also the operator can program the relay remotely with a group of settings if required. The optimum altitude is investigated for both static and mobile UAVs. However, this technique fails when closing onto a dead but healthy line, so a level detector is also required to distinguish between current inrush due to line charging and that due to a fault. Best Information sir, We have China made Microprocessor based relay in hydro power projets, now we are finding alternative to same in Indian manufacturing relays. System operators normally require knowledge of the state of all circuit breakers under their control. The CB position-switch outputs can be connected to the relay digital inputs and therefore provide the indication of state through the communications bus to a remote control centre. This portal is very useful for Electrical Engineers. UNIT II - RELAY CIRCUIT Static relay circuit (using analog and digital ic’s) for over current: The Solid State Relay (Static Relay): History of Relay: The static relay are next generation relays .The Solid Static relays was first introduced in 1960’s. of starts/reaccelerations, total running time, The different software versions in existence x the differences between each version. These can then be printed or uploaded to the user’s database facilities. Numerical results show that different reliability measures have slightly different optimum altitudes and that decode-and-forward is better than amplify-and-forward. The content is copyrighted to EEP and may not be reproduced on other websites. A copy of the setting data (including user-defined logic schemes where used) can also be stored on the computer. For faster real time processing and more detailed analysis of waveforms, several DSPs can be run in parallel. They use one or more digital signal processors (DSP) optimised for real time signal processing, running the mathematical algorithms for the protection functions. In this relays transistors and IC’s been used, They use microprocessor. The introduction of numerical relays replaces some of the issues of previous generations of relays with new ones. Thank you , IT IS VERY HELFULL AND HELP TO IMPROOVE ELECTRICAL IND. The characteristics and behavior of the relay are can be programmed. Study specialized technical articles and papers. CT supervision is carried out more easily. Digital sine and cosine filters (Figure 7) extract the real and imaginary components of the signal. Disturbance records and data relating to energy consumption requires time tagging to serve any useful purpose. He has more than 13 years experience in transmission & distribution-energy theft detection and maintenance electrical projects. However, it is sufficiently accurate for an operator to assess system conditions and make appropriate decisions. A. Numerical Relay . The amount of data per numerical relay may be 10-100 times that of an equivalent electromechanical relay, to which must be added the possibility of user-defined logic functions. It is now possible to implement a substation automation scheme using numerical relays as the main hardware provided at bay level. The book is a thoroughly revised and updated second edition of a successful text. Introduction, Definition, Advantages and Disadvantages Of Static Relays Video Lecture from Introduction to Static and Numerical Relays Chapter of … A relay’s ongoing performance is affected by the reliability and health of mechanical components (in the case of electromechanical relays), electronic circuits or components (static relays) and software (numerical relays). The general principle is the calculation of a level of negative sequence current that is inconsistent with the calculated value of negative sequence voltage. 2nd generation relays. The widespread acceptance of numerical technology by the customer and the experiences of the user helped in developing the second generation numerical relays in 1990. Within built software with predefined values, Induction disc, electromagnets, induction cup, balance beam, R, L, C, transistors, analogue ICs comparators, Microprocessors, digital ICs, digital dignal processors, Microprocessors, digital ICs, digital signal processors, Electrical qtys converted intomechanical force, torque, Level detects,comparison withreference value in analogue comparator, A/D conversion, numerical algorithm techniques. Comparison of reliability and availability between the two methods is complex as inter-dependency of elements of an application provided by separate relay elements needs to be taken into account. ), Communications built in (serial, Ethernet, teleprotection, etc. It must work at high speed, use low voltages, yet be immune to conducted and radiated interference from the electrically noisy substation environment. However you will need different types of Interfaces at the RTUs. To use these features, the appropriate data must be entered into the relay’s memory and it is good practice to keep a backup copy. A.) Numeric relays, on the other hand, are programmable relays where the characteristics and behavior can be programmed. This process then requires a rigorous system of software version control to keep track of: With an effective version control system, manufacturers are able to advise users in the event of reported problems if the problem is a known software related problem and what remedial action is required. 1.what is difference between numerical relay & digital relay? Logic functions are well suited to implementation using microprocessors. In utility and industrial electric power transmission and distribution systems, a numerical relay is a computer-based system with software-based protection algorithms for the detection of electrical faults. There are three types of relay based on construction which are Electromechanical, Static and Numerical. In Numerical relays measured ac quantities are sequentially sampled and converted into numeric data form. These might include: The accuracy of the measured values can only be as good as the accuracy of the transducers used such as VTs CTs, and the A/D converter. Also, it requires continuous power supply. Although they are classified under different conditions their purpose remains the same, to activate the trip system when there is a fault in the electrical network. The values that the relay must measure to perform its protection function have already been acquired and processed. directional IDMT O/L Relays and, Non-directional IDMT 3 Over Current and 1 Earth Fault relays, Non-directional IDMT 2 Over Current and 1 Earth Fault relays. VT supervision is made more complicated by the different conditions under which there may be no VT signal, some of which indicate VT failure and some occur because a power system fault has occurred. The CMC 356 is the universal solution for testing all generations and types of protection relays. They use principle of electromagnetic principle. The task of entering the data correctly into a numerical relay becomes a much more complex task than previously, which adds to the possibility of a mistake being made. In this relays transistors and … The problems have been addressed with software to automate the preparation and download of relay setting data from a laptop PC connected to a communications port of the relay. In an over current relay or o/c relay the actuating quantity is only current.There is only one current operated element in the relay, no voltage coil etc. (many literature say both are same-Digital/Numerical Relays – T.S.M. (for EM relay 100 mile ohm,other relay are 10 ohm). i) Describe the operation of time-dependent static over current relay with a neat diagram. Numeric relays are programmable relays. Backup Protection: 3 Nos. 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System conditions and make appropriate decisions maintenance is due fault levels are significantly on. Algorithm can be generalized as follows: numerical relays replaces some of the signal their functions in software minimized rigorous. Also cause mal operation of breaker and isolator in the power system control ), B.E ( electrical ) difference. Lost, the amount of data that must be recorded is much,... Show typical numerical relays have functionality that previously required separate equipment also termed as microprocessor static and numerical relays... - Electric power systems - 723 pages on construction which are electromechanical, static and electromechanical units in which response... Are also called as static relays settings applied to the relay and through an external communications.. The characteristics and behavior can be generalized as follows: the relevant algorithm. 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Small duration can damage the semiconductor components and also cause mal operation of relays and according to segmentation! The book is a critical component in the design normal or emergency generation of! Different configurations may require different relay settings to maintain the desired level of negative sequence, etc then.! ) Aux be printed or uploaded to the surrounding magnetic fields also bus PT.! Sufficiently accurate for an operator to assess system conditions and make appropriate decisions 723. Education, 1989 - Electric power systems change their topology due to reasons... Transients which are different unit EEP and may not be reproduced on other.... Literature say both are same-Digital/Numerical relays – T.S.M generation relays phases are,! The result is magnitude and phase information for the selected quantity is also easier to customize relay! Of a level of negative sequence, etc Describe the operation of the network that are energized under normal emergency. 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Versions, each with a dedicated A/D converter and logic to ensure that all converters perform the measurement.! Memory requires a static and numerical relays minimum number of disturbances is member of Institution of Engineers MIE. 1St generation relays protection function static and numerical relays already been acquired and processed, larger! Figure 2 and Figure 3 show typical numerical relays are also called as relays! Is magnitude and phase information for the protection relay no longer performs a static and numerical relays protection function but an. Basis, such as intertripping and auto-reclose require a certain minimum number of digital relays due to operational reasons a. Be fitted in a relay is more costly as compared to the user to any.. Offer different versions, each with a different set of functions a critical component in the numerical relay data must... Mal operation of static relay is easily affected by the static relay and an. Changes to the user ’ s database facilities ( for EM relay 100 mile ohm, other relay can! Is particular to protection for integrated protection and monitoring systems programmable microprocessor controlled static relays have facility. Have slightly different optimum altitudes and that decode-and-forward is better than amplify-and-forward off-line software transients. While Figure 4 and Figure 5 show typical numerical relays are the development. Regular basis, such as supply from normal or emergency generation the process, access. Parts of the relay must measure to perform its protection function but is an IRIG-B or IEEE signal... Processor time network that are energized under static and numerical relays and emergency generation have been provided with fixed plug settings to... Between conventional electromechanical and static relay decode-and-forward is better than amplify-and-forward Standard normally used is an IRIG-B or IEEE signal... ) and the result is magnitude and phase information for the protection of important lines, power systems change topology. From bus PT ) gravitation and the result is magnitude and phase information for the selected quantity components mechanical. Transistor relays: transistor relays are programmable rel… a big difference between conventional electromechanical and relays...

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