A.) It helps you. Function parameters are usually displayed on the front panel of the relay and through an external communications port. As with earlier generations of relays and according to market segmentation, manufacturers offer different versions, each with a different set of functions. Transistor Relays: Transistor relays are the most widely used static relays. Get access to premium HV/MV/LV technical articles, electrical engineering guides, research studies and much more! A transistor amplifier . 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. Scope For more information on the different types of disturbance recording, read this technical article. Numeric relays are programmable relays. Powerful six-phase relay testing and more. Traditional electromechanical and static protection relays offers single-function and single characteristics. There value may vary with respect to temperature also. 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. 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. This relay consists of two rectifier bridges and a moving coil or polarized moving iron relay. Numerical relays are natural developments of digital relays due to advances in technology. The software provided is commonly organised into a series of tasks operating in real time. Learn about power engineering and HV/MV/LV substations. The implementation of logic in a relay is not new, as functions such as intertripping and auto-reclose require a certain amount of logic. Conventional electromechanical and static relays are hard wired relays.Their wiring is fixed, only their setting can be manually changed. In this relays transistors and … This is often done using a Discrete Fourier Transform (DFT) and the result is magnitude and phase information for the selected quantity. Historically, electromechanical and static relays have been provided with fixed plug settings applied to the relay. I found the article very informative thank you, The articale is very nice but i have few question. 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. It consists of one or more digital signal processors, some memory, digital and analogue input/output (I/O), and a power supply. 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. 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. As the power of microprocessors continues to grow and pressure on operators to reduce costs continues, this trend will continue. This calculation is repeated for all of the quantities of interest. A numerical relay can record all of these parameters and hence be configured to send an alarm when maintenance is due. CT supervision is carried out more easily. Function Single function Single function Multi function Single function how numerical relay can be a single function ?? Digital sine and cosine filters (Figure 7) extract the real and imaginary components of the signal. The relay memory requires a certain minimum number of cycles of measured data to be stored for correct signal processing and detection of events. Incorrect results are then obtained. 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. Many numerical relays have the facility for time synchronisation from an external clock. He is member of Institution of Engineers (MIE), India. Some of the new issues that must be addressed are as follows: Numerical relays perform their functions in software. 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’. The optimum altitude is investigated for both static and mobile UAVs. Figure 1, Figure 2 and Figure 3 show typical numerical relays, while Figure 4 and Figure 5 show typical numerical relay boards. Relays detect and locate faults by measuring electrical quantities in the power system which are different during normal and intolerable conditions. 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. However, it is sufficiently accurate for an operator to assess system conditions and make appropriate decisions. 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. Over Current/ Earth Fault:When excessive current flows through a system it will trip the circuit br… 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 ”. In static relays, the measurement is performed by electronic/magnetic/optical or other components without mechanical motion. Typical functions that may be found in a numerical relay other than protection functions are described in this section. The general principle is the calculation of a level of negative sequence current that is inconsistent with the calculated value of negative sequence voltage. (for EM relay 100 mile ohm,other relay are 10 ohm). 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. Under this high performing range, we are providing our clients with Static Earth Leakage Relay, Static Earth Fault Relay and Numerical Over Current Relay. 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. 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. 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. Similarly, the amount of data that must be recorded is much larger, requiring larger storage. Also numerical relays have functionality that previously required separate equipment. The first protection devices based on microprocessors were employed in 1985. In a static over current relay, inverse time characteristics are obtained by . 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. 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. Figure 2 shows cost comparison of numerical relay with electromechanical and static relay [1]. In industrial and small distribution networks, this may be all that is required. A big difference between conventional electromechanical and static relays is how the relays are wired. 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. please explain, Its very informative artical.thank you sir. Position of relay: Relay can be installed at any location and at any position. The CMC 356 is the universal solution for testing all generations and types of protection relays. 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. Operating Principle: They use principle of electromagnetic principle. Disturbance records and data relating to energy consumption requires time tagging to serve any useful purpose. 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. Numeric relays, on the other hand, are programmable relays where the characteristics and behavior can be programmed. 1.what is difference between numerical relay & digital relay? This relay has to be installed straight only and away from magnetic field. The introduction of numerical relays replaces some of the issues of previous generations of relays with new ones. 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. 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. ), Communications built in (serial, Ethernet, teleprotection, etc. Therefore solid state relays are also called as static relays. 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. Such voltage spikes of small duration can damage the semiconductor components and also cause mal operation of relays. 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. 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. Static relays possess the advantages of having. The internal communications bus links the hardware and therefore is a critical component in the design. First generation numerical relays were mainly designed to meet the static relay protection Jignesh Parmar has completed M.Tech (Power System Control), B.E (Electrical). A 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 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. 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. Numerical relays perform many more functions than earlier generations of relays so testing them is more complex. Tata McGraw-Hill Education, 1989 - Electric power systems - 723 pages. The choice of a protection relay rather than some other device is logical as the protection relay is probably the only device that is virtually mandatory on circuits of any significant rating. Most numerical relays are also multifunctional. 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. Backup Protection: 3 Nos. Dear Jignesh A very well compiled work. ii) Write the purpose of Start of Conversion (S/C) and End of Conversion (E/C) signals in the Numerical Relay? Depend upon gravitation and the value changes to the surrounding magnetic fields also. The characteristics and behavior of the relay are can be programmed. More than 7 decades ago, ALIND pioneered the manufacture of Aluminium conductors in India. Study specialized technical articles and papers. Main Protection: Switched distance scheme (fed from bus PT). Software problems are minimized by rigorous use of software design techniques and the ability to download updated software. Other software depends on the function of the relay, but can be generalized as follows: The relevant software algorithm is then applied. of starts/reaccelerations, total running time, The different software versions in existence x the differences between each version. 2nd generation relays. An integrating circuit . Based on Logic These classifications are made on the basis of logical operation of the relay 1. Tell us what you're thinking... we care about your opinion! It incorporates the latest developments in semiconductor technology and its applications to power system protection. ALIND -The Power Movers. If suitable VTs are used, supervision of the VT/CT supplies can be made available. Serious over voltage is also caused by breaking of control circuit, relay contacts etc. Numerical relays are the product of the advances in technology from digital relays. Generally, there are several different types of numerical protection relays. low burden on the CT and VT, fast operation, absence of mechanical inertia and; contact trouble, long life and; less maintenance. A big difference between conventional electromechanical and static relays is how the relays are wired. Each relay element is in software so with modular hardware the main signal processor can run a vast variety of relay elements. The static relay is more costly as compared to the electromagnetic relay. These can then be printed or uploaded to the user’s database facilities. Firstly the quantities of interest are determined from the information in the data samples. They use one or more digital signal processors (DSP) optimised for real time signal processing, running the mathematical algorithms for the protection functions. Good work Jignesh, But for El Mechanical Relay like CDD21 (Alstom) Aux. Where multiple processors are used, one of them is a general controller of the I/O, Human Machine Interface (HMI) and any associated logic while the others are dedicated to the protection relay algorithms. The content is copyrighted to EEP and may not be reproduced on other websites. Different configurations may require different relay settings to maintain the desired level of network protection. 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 … 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. [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. He has more than 13 years experience in transmission & distribution-energy theft detection and maintenance electrical projects. D. A differentiating circuit 3 Reviews. demand in a period ( kW, kVAr; average and peak values), Motor start information (start time, total no. 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. The protection relay no longer performs a basic protection function but is an integral and major part of a substation automation scheme. 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. Introduction, Definition, Advantages and Disadvantages Of Static Relays Video Lecture from Introduction to Static and Numerical Relays Chapter of … Numeric relays, on the other hand, are programmable relays where the characteristics and behavior can be programmed. An essential component is the Real Time Operating System (RTOS) which ensures that the other tasks are executed when required, in the correct priority. It may be inconvenient to download the record immediately, so facilities may be provided to capture and store a number of disturbances. For faster real time processing and more detailed analysis of waveforms, several DSPs can be run in parallel. Supply is not required and all the Numerical Relay are Multi function relays. The most common are relay comparators based on rectifier bridges, which can be arranged as either amplitude or phase comparators. setting can be manually changed. The argument against putting many features into one piece of hardware centres on the issues of reliability and availability. Present generation relays. 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. Many functions previously implemented in separate items of hardware can then be included in a single item. The values that the relay must measure to perform its protection function have already been acquired and processed. Numerical Relays working explained in this post with the help of a Numerical relay used in industrial applications. Numerical relays are natural developments of digital relays due to advances in technology. 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Relays the above diagram shows the schematic of an electromechanical relay called as relays. Element is in software so with modular hardware the main signal processor run! Relay boards these can then be printed or uploaded to the electromagnetic relay however will! Of being programmed using suitable off-line software printed or uploaded to the relay memory a...