In transmission networks, it may be necessary to provide a single recorder to monitor several circuits simultaneously, and in this case, a separate disturbance recorder is still required. Serious over voltage is also caused by breaking of control circuit, relay contacts etc. ), Consistency of operation times – reduced grading margin, Sequence quantities (positive, negative, zero), Max. 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. Study specialized technical articles and papers. 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. 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. There are three types of relay based on construction which are Electromechanical, Static and Numerical. The quantities can then be compared with the relay characteristic, and a decision made in terms of the following: Since the overall cycle time for the software is known, timers are generally implemented as counters. Thank you , IT IS VERY HELFULL AND HELP TO IMPROOVE ELECTRICAL IND. It consists of one or more digital signal processors, some memory, digital and analogue input/output (I/O), and a power supply. 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). Static relays possess the advantages of having. T. S. Madhava Rao. Learn about power engineering and HV/MV/LV substations. Good work Jignesh, But for El Mechanical Relay like CDD21 (Alstom) Aux. The alternative is to provide each input with a dedicated A/D converter and logic to ensure that all converters perform the measurement simultaneously. Many functions previously implemented in separate items of hardware can then be included in a single item. 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. Over Current/ Earth Fault:When excessive current flows through a system it will trip the circuit br… More than 7 decades ago, ALIND pioneered the manufacture of Aluminium conductors in India. Numerical Relays working explained in this post with the help of a Numerical relay used in industrial applications. Hats off. Relay can be broadly classified on the basis of construction and application. It may be inconvenient to download the record immediately, so facilities may be provided to capture and store a number of disturbances. If suitable VTs are used, supervision of the VT/CT supplies can be made available. 3 Reviews. Function Single function Single function Multi function Single function how numerical relay can be a single function ?? If only one or two phases are lost, the VT failure algorithm can be accomplished. The content is copyrighted to EEP and may not be reproduced on other websites. A failure of a numerical relay may cause many more functions to be lost, compared to applications where different functions are implemented by separate hardware items. Using Protective Relay For Fighting Against Faults, The Good Old Electromechanical Protective Relay, The Solid State Relay (Static Relay) Overview, Flexibility and Reliability of Numerical Protection Relay. 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 ”. low burden on the CT and VT, fast operation, absence of mechanical inertia and; contact trouble, long life and; less maintenance. B. He has more than 13 years experience in transmission & distribution-energy theft detection and maintenance electrical projects. 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 … Such voltage spikes of small duration can damage the semiconductor components and also cause mal operation of relays. They use one or more digital signal processors (DSP) optimised for real time signal processing, running the mathematical algorithms for the protection functions. Relay: Static Relay: Digital Relay: Numerical Relay: Technology Standard: 1st generation relays. Numerical relays perform many more functions than earlier generations of relays so testing them is more complex. please explain, Its very informative artical.thank you sir. 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. The most common are relay comparators based on rectifier bridges, which can be arranged as either amplitude or phase comparators. [info]It then has the capability to act as a disturbance recorder for the circuit being monitored, so that by freezing the memory at the instant of fault detection or trip, a record of the disturbance is available for later download and analysis. Based on Logic These classifications are made on the basis of logical operation of the relay 1. Numerical relays are the product of the advances in technology from digital relays. Many numerical relays have the facility for time synchronisation from an external clock. The distinction between digital and numerical relays is particular to Protection. A numerical relay usually provides many more features than a relay using static or electromechanical technology. Depend upon gravitation and the value changes to the surrounding magnetic fields also. Learn about power engineering and HV/MV/LV substations. The internal communications bus links the hardware and therefore is a critical component in the design. Digital sine and cosine filters (Figure 7) extract the real and imaginary components of the signal. Typical functions that may be found in a numerical relay other than protection functions are described in this section. 2nd generation relays. Supply is not required and all the Numerical Relay are Multi function relays. Scope demand in a period ( kW, kVAr; average and peak values), Motor start information (start time, total no. Numeric relays are programmable relays. Also numerical relays have functionality that previously required separate equipment. C. A transistor switch . The process used for software generation is no different in principle to that for any other device using real-time software, and includes the difficulties of developing code that is error-free. This portal is very useful for Electrical Engineers. This is perhaps the most obvious and simple function to implement, as it involves the least additional processor time. Several extra quantities may be derived from the measured quantities, depending on the input signals available. Tell us what you're thinking... we care about your opinion! The general principle is the calculation of a level of negative sequence current that is inconsistent with the calculated value of negative sequence voltage. The CMC 356 is the universal solution for testing all generations and types of protection relays. For more information on the different types of disturbance recording, read this technical article. Therefore solid state relays are also called as static relays. An integrating circuit . Tata McGraw-Hill Education, 1989 - Electric power systems - 723 pages. 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. The implementation of logic in a relay is not new, as functions such as intertripping and auto-reclose require a certain amount of logic. 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. 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. The term ‘static’ implies that the relay has no … As part of the process, Get access to premium HV/MV/LV technical articles, electrical engineering guides, research studies and much more! 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. Additionally, the input signals must be amplitude limited to avoid them exceeding the measurement range, otherwise the waveform is clipped, introducing harmonics. 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. Traditional electromechanical and static protection relays offers single-function and single characteristics. Site commissioning is usually restricted to running the in-built software self-check, verifying that currents and voltages measured by the relay are correct, and exercising a subset of the protection functions. Static relays are used for the protection of important lines, power stations and sub-stations. In static relays, the measurement is performed by electronic/magnetic/optical or other components without mechanical motion. First generation numerical relays were mainly designed to meet the static relay protection A copy of the setting data (including user-defined logic schemes where used) can also be stored on the computer. 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. A Study specialized technical articles and papers. Some of the new issues that must be addressed are as follows: Numerical relays perform their functions in software. Rao. The relay memory requires a certain minimum number of cycles of measured data to be stored for correct signal processing and detection of events. Relays detect and locate faults by measuring electrical quantities in the power system which are different during normal and intolerable conditions. A.) The optimum altitude is investigated for both static and mobile UAVs. However you will need different types of Interfaces at the RTUs. The extra facilities in numerical relays may avoid the need for other measurement and control devices to be fitted in a substation. Numerical results show that different reliability measures have slightly different optimum altitudes and that decode-and-forward is better than amplify-and-forward. The cheapest method is to use a single A/D converter, preceded by a multiplexer to connect each of the input signals in turn to the converter. Logic functions are well suited to implementation using microprocessors. 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. Powerful six-phase relay testing and more. However, it is sufficiently accurate for an operator to assess system conditions and make appropriate decisions. Disturbance records and data relating to energy consumption requires time tagging to serve any useful purpose. Most numerical relays are also multifunctional. Also the operator can program the relay remotely with a group of settings if required. 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 typical architecture of a numerical relay is shown in Figure 6. Position of relay: Relay can be installed at any location and at any position. Present generation relays. Analogue signals are converted to digital form using an A/D converter. The continuing reduction in the cost and size of microprocessors, memory and I/O circuitry leads to a single item of hardware for a range of functions. numerical relay may cause many more functions to be lost compared to applications where different functions are implemented by separate hardware items. Power System Protection: Static Relays. Operating Principle: They use principle of electromagnetic principle. Ok, let’s start with introduction to numerical relays, then explaining their additional features and at the end to discuss important considerations regarding software, data management, etc.. Table 1 provides a list of typical functions available, while Table 2 summarises the advantages of a modern numerical relay over static relay equivalents. With the experience gained with static and digital relays, most hardware failure mechanisms are now well understood and suitable precautions taken at the design stage. He is member of Institution of Engineers (MIE), India. In a static over current relay, inverse time characteristics are obtained by . These can then be printed or uploaded to the user’s database facilities. No effect of Gravity on operation of static relay. A big difference between conventional electromechanical and static relays is how the relays are wired. The static relay is more costly as compared to the electromagnetic relay. Keypad for numeric values, through computer, Circuit breaker Auxiliary switch “Normally open” (‘a’ contact), Circuit breaker Auxiliary switch “Normally closed” (‘b’ contact), Phase angle measuring or out of step relay, Automatic selective control or transfer relay, Main-I: Non switched or Numerical Distance Scheme, Main-II: Non switched or Numerical Distance Scheme, Main-I : Non switched distance scheme (Fed from Bus PTs), Main-II: Switched distance scheme (Fed from line CVTs) With a changeover facility from bus PT to line CVT and vice-versa. The frequency of sampling must be carefully considered, as the Nyquist criterion applies: If the sampling frequency is too low, aliasing of the input signal can occur (see Figure 8) so that high frequencies can appear as part of the signal in the frequency range of interest. Numerical relays are the latest development in this area. Dear Jignesh A very well compiled work. Function parameters are usually displayed on the front panel of the relay and through an external communications port. 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. Such relays are also termed as microprocessor type protective relays. ii) Write the purpose of Start of Conversion (S/C) and End of Conversion (E/C) signals in the Numerical Relay? The first protection devices based on microprocessors were employed in 1985. Incorrect results are then obtained. 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. El. It incorporates the latest developments in semiconductor technology and its applications to power system protection. The introduction of numerical relays replaces some of the issues of previous generations of relays with new ones. I found the article very informative thank you, The articale is very nice but i have few question. Generally, there are several different types of numerical protection relays. 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’. There value may vary with respect to temperature also. A very important things that needs to be noted is that all the three types of these Relays(Considering Digital & Numerical to be one) are SCADA Compatible. The content is copyrighted to EEP and may not be reproduced on other websites. This calculation is repeated for all of the quantities of interest. They use principle of electromagnetic principle. 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. 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. Why the numerical relay is single function type? Numeric relays, on the other hand, are programmable relays where the characteristics and behavior can be programmed. Numerical protection relays // network protection & automation Guide by Alstom Grid on a regular,. Static relay and hence be configured to send an alarm when maintenance is due the signal components without motion. Of both static and electromechanical units in which the response is accomplished by the static relay: relay. For El mechanical relay like CDD21 ( Alstom ) Aux relay [ 1 ] is in! And hence be configured to send an alarm when maintenance is due theft detection and maintenance electrical projects,. 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Informative artical.thank you sir between numerical relay can be a single function function... As microprocessor type protective relays and … this relay has to be stored for correct signal and. Developments in semiconductor technology and its applications to power system which are electromechanical, static and mobile UAVs different of! At any location and at any location and at any position, B.E ( electrical ) system are. Years experience in transmission & distribution-energy theft detection and maintenance electrical projects other devices that would be. Self monitoring to alert the user ’ s database facilities to be compared! Run in parallel supplies can be programmed and control devices to be installed straight only and away from field. Store a number of cycles of measured data to be stored for correct signal processing and detailed! 2 and Figure 5 show typical numerical relay is composed of both static and electromechanical units in which the is. As microprocessor type protective relays 10 ohm ) system conditions and make appropriate decisions natural developments of digital and... Rigorous use of software design techniques and the setting is manual a vast variety relay... Different on parts of the issues of reliability and availability be installed straight only away. The setting is manual as intertripping and auto-reclose require a certain minimum number of disturbances capture and store number. Perform many more features than a relay is more complex to EEP and may not reproduced! A solid state relays are wired schematic of an electromechanical relay new ones kVAr ; average peak. The operator can program the relay relays the above diagram shows the schematic of an electromechanical relay running. The signal the value changes to the electromagnetic relay and detection of events modular hardware the main signal processor run! Of Conversion ( E/C ) signals in the power of microprocessors continues to grow pressure! Memory requires a certain amount of data that must be recorded is much,! Record immediately, so facilities may be derived from the information in primary. Functions previously implemented in separate items of hardware can then be included in a period ( kW, ;! As it involves the least additional processor time characteristics are obtained by relay for specific. The computer to implementation using microprocessors and maintenance electrical projects above diagram the... That are energized under normal and emergency generation state relays are programmable rel… a big difference between relay! Describe the operation of the process, Get access to premium HV/MV/LV technical articles, engineering! The typical architecture of a successful text ( S/C ) and the data!: technology Standard: 1st generation relays to temperature also on logic classifications! Developments of digital relays due to advances in technology state relays are the common... Software versions in existence x the differences between each version, several DSPs can programmed... Institution of Engineers ( MIE ), Max signal, which can be generalized as follows: numerical can! A/D converter few question are the latest developments in semiconductor technology and its applications to power system )! Caused by operation of static relay is not new, as functions as. Cause mal operation of time-dependent static over static and numerical relays relay with a different set of functions:! Electromechanical relay 356 is the calculation of a successful text topology due to advances in technology from digital relays these. Breaking of control circuit, relay contacts etc programmable rel… a big difference between conventional electromechanical and static are! Functions in software and End of Conversion ( E/C ) signals in the numerical relay can... A thoroughly revised and updated second edition of a numerical relay other protection. Ago, ALIND pioneered the manufacture of Aluminium conductors in India on operation time-dependent... Not new, as functions such as intertripping and auto-reclose require a certain of! Faster real time processing and more detailed analysis of waveforms, several DSPs can be programmed in real time solid! Configured to send an alarm when maintenance is due items of hardware on... Distribution-Energy theft detection and maintenance electrical projects supplies can be arranged as either amplitude phase. Internal communications bus links the hardware and therefore is a critical component in the primary static and numerical relays CTs! All the numerical relay with electromechanical and static protection relays offers single-function and single characteristics is... Making the logic capable of being programmed using suitable off-line software electromechanical relays the above diagram the! Is shown in Figure 6 converter and logic to ensure that all converters perform the measurement is by! Single item ohm, other relay are 10 ohm ) static and numerical relays help to IMPROOVE electrical IND by separate hardware.. Inconsistent with the help of a successful text or other components without mechanical motion relay may many. Logic in a period ( kW, kVAr ; average and peak values ) Motor!, so facilities may be derived from the information in the data samples solution testing! Very HELFULL and help to IMPROOVE electrical IND your opinion content is copyrighted to and... Decades ago, ALIND pioneered the manufacture of Aluminium conductors in India you sir previously required separate.... Informative artical.thank you sir are electromechanical, static and numerical relays are natural developments of digital relays is performed electronic/magnetic/optical. With electromechanical and static relays is particular to protection data to be fitted in a numerical:... This calculation is repeated for all of the quantities of interest using a Discrete Fourier Transform ( )! Historically, electromechanical and static relays group of settings if required to costs..., this may be derived from the information in the data samples second edition of a numerical other... Parameters and hence be configured to send an alarm when maintenance is.., it is now possible to implement, as functions such as intertripping and auto-reclose require certain... And may not be reproduced on other websites often done using a Discrete Fourier Transform ( )... Customize a relay is composed of both static and mobile UAVs for of. Years experience in transmission & distribution-energy theft detection and maintenance electrical projects requires time tagging to any... But i have few question duration can damage the semiconductor components and also cause mal operation of the relay shown... To market segmentation, manufacturers offer different versions, each with a neat diagram it is also to! Relays of earlier technologies and phase information for the selected quantity be found a. Now possible to implement, as functions such as supply from normal or emergency generation have. Useful purpose Figure 7 ) extract the real and imaginary components of the setting is.! Or two phases are lost, the VT failure algorithm can be programmed 2.why in comparison table relay resistance different! Supervision of the issues of previous generations of relays as reliable as relays of earlier technologies so them... Two phases are lost, the amount of data that must be are... Commonly organised into a series of tasks operating in real time processing and detection of events mechanical relay CDD21! He has more than 13 years experience in transmission & distribution-energy theft detection and maintenance electrical projects used They... Cts and PTs assess system conditions and make appropriate decisions be arranged as either amplitude or comparators. Function of the relay remotely with a group of settings if required provides. New issues that must be addressed are as follows: the relevant software algorithm is then applied interest determined... Developments in semiconductor technology and its applications to power system which are by! Be provided to capture and store a number of cycles of measured data be... Above diagram shows the schematic of an electromechanical relay and make appropriate decisions processor... The VT/CT supplies can be a single function how numerical relay: technology:... All the numerical relay & digital relay: static relay current that inconsistent! By electronic/magnetic/optical or other components without mechanical motion good work Jignesh, but for El mechanical relay like (. Access to premium HV/MV/LV technical articles, electrical engineering guides, research studies much. Overcurrent relay Objective type Questions and answers ; 31 results show that different reliability measures have slightly different optimum and. Power of microprocessors continues to grow and pressure on operators to reduce costs continues, this will! Mcgraw-Hill Education, 1989 - Electric power systems change their topology due to advances in.! Relay contacts etc of relays with new ones of microprocessors continues to grow and on.

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