we respect your privacy and take protecting it seriously. The numerical relay is one of electrical base of the software protection against to detect the natural & unnatural fault in the electrical machinery. Then a relatively simple microprocessor does a slow speed A/D conversion of the DC signal, integrates the results to create the time-overcurrent curve response, and trips when the integration rises above a set-point. Functions: 1 relay can perform various functions. Only the fundamental component is needed for most protection algorithms, unless a high speed algorithm is used that uses subcycle data to monitor for fast changing issues. Therefore, a simple solution would be to keep metering and protection functionality separate. [1] Such relays are also termed as microprocessor type protective relays. The relay analyzes the resultant A/D converter outputs to determine if action is required under its protection algorithm(s). Based on type, medium voltage protection relays can be divided into electromechanical & static relays and digital & numerical relays. Rao Publisher: Tata McGraw-Hill Education ISBN: 9780070588554 Size: 67.74 MB Format: PDF, Docs Category : Electric power systems Languages : en Pages : 227 View: 2237 Get Book. ELECTRO-MECHANICAL RELAY The below figure shows the schematic of an Electro-mechanical relay. digital relays, static relays or even electromechanical relays. One is RAM (Random Access Memory) and ROM (Read Only Memory). 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. a digital protective relay is a computer-based system with software-based protection algorithms for the detection of electrical faults.Such relays are also termed as microprocessor type protective relays. Alternatively, a variable gain amplifier can be used along with the A/D converter. Communication languages may include Modbus, DNP3 or IEC61850 protocols. Digital And Smart Grid Enterprises - Offering GE / Alstom P442 Numerical Distance Protection Relays, मोटर प्रोटेक्शन रिले, मोटर संरक्षण रिले in Navi Mumbai, Maharashtra. In the era of electromechanical and solid state relays, any one relay could implement only one or two protective functions, so a complete protection system may have many relays on its panel. The analog values are compared to settings made by the user via potentiometers in the relay, and in some case, taps on transformers. 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. In some relays, a short history of the entire sampled data is kept for oscillographic records. Numerical relays are classified broadly into four different types as Overcurrent relays, Distance relays, Directional relays and Differential relays depending upon their applications. The generalized numerical relay consists of a minimum set of hardware modules and … Relay: Static Relay: Digital Relay: Numerical Relay: Technology Standard: 1st generation relays. The processing of numerical relays using DSP is also optimized for real-time signal processing applications [1]. A listing of device numbers is found at ANSI Device Numbers. Lecture -16 PSM Setting and Phase Relay Coordination (Tutorial) Lecture -17 Earth Fault Protection using Overcurrent Relays; Module-5 Directional Overcurrent Protection. George was chairman of the IEEE Power System Relaying and Control (PSRC) committee (1981-1982) as well as a member of the "Computer Relaying Subcommittee" which was created by the PSRC in 1971 and disbanded in 1978. The static relay is more costly as compared to the electromagnetic relay. Operating Principle: They use principle of electromagnetic principle. Westinghouse developed the first digital relay with the Prodar 70 [5] being developed between 1969 and 1971. Numerical relay. A relay that functions to prevent overheating of the field excitation winding by reducing or interrupting the excitation of the shunt field. Multiplexer and Analog to Digital Converter: Numerical Relays are provided with serial and parallel ports for the interconnection with control and communication system of the substation. While the great majority of feeder relays in new applications today are digital, the solid state relay still sees some use where simplicity of the application allows for simpler relays, which allows one to avoid the complexity of digital relays. The analog single from the Power System is stepped down using Current Transformer and Potential Transformer and then fed to the Numerical Relay using low pass filter. Software: Numerical Relays are equipped with software to communicate with external device to program to Relay or one can program by navigating through the Relay Menu. For example, one may use 16 bit A/D converter in place of 12 bit A/D converter. Thus, a solution to reduce the impact of CCVT transient on distance relays can be obtained. This resolution may be inadequate for metering purposes. (IA/ICTL/IAC) [60] field relay (power system device function numbers) A relay that functions on a given or abnormally low value or failure of machine field current, or on an excessive value 1 relay can perform only 1 function. Among different types of relays, the electromechanical relay has the lowest cost. It is capable of analyzing whether the relay should trip or restrain from tripping based on parameters set by the user, compared against many functions of its analogue inputs, relay contact inputs, timing and order of event sequences. The relay is capable of applying advanced logic. The AC signal is then sampled by the relay's analog-to-digital converter from 4 to 64 (varies by relay) samples per power system cycle. In some solid-state relays, a simple microprocessor does some of the relay logic, but the logic is fixed and simple. Low pass filter is incorporated in the input module to eliminate any noise single induced in the line due to corona or induction effect of nearby high voltage line. The most attractive feature of such relay is that it works on FIFO (First In, First Out). A Sample and Hold (S/H) circuit is used to keep the rapidly changing instantaneous value constant during the period of conversion for processing. Based on operation mechanism protection relay can be categorized as electromagnetic relay, static relay and mechanical relay. Separate terminals are provided for the analog and digital inputs. For instance, a differential element refers to the logic required to monitor two (or more) currents, find their difference, and trip if the difference is beyond certain parameters. Let a 12 bit unipolar A/D converter be used for sampling current signal. As a minimum, magnitude of the incoming quantity, commonly using Fourier transform concepts (RMS and some form of averaging) would be used in a simple relay function. Event and Disturbance Recording is a must feature for a digital relay because these data are used for troubleshooting any event. Low voltage and low current signals (i.e., at the secondary of a voltage transformers and current transformers) are brought into a low pass filter that removes frequency content above about 1/3 of the sampling frequency (a relay A/D converter needs to sample faster than twice per cycle of the highest frequency that it is to monitor). A Digital Relay comprises both Hardware and Software. Suppose if it happens to be the number of disturbances exceeds 50 then the Relay will delete the last Disturbance and will register new disturbance. Electromechanical and static relays have fixed wiring and the setting is manual. Mech. The event recording would include some means for the user to see the timing of key logic decisions, relay I/O (input/output) changes, and see, in an oscillographic fashion, at least the fundamental component of the incoming analogue parameters. For example, with 16 bit A/D converter, 32 bit processor is the natural choice. Numerical Relays working explained in this post with the help of a Numerical relay used in industrial applications. The working of the relay depends on the electrical components. This implies that resolution of A/D converter is 2000/(2, What is IGBT? In this relays … (1 relay can be used as over current relay, under voltage relay etc.) Lecture -18 Directional Overcurrent Relaying; Lecture -19 Directional Overcurrent Relay Coordination (Tutorial) Lecture -20 Directional Overcurrent Relay Coordination in Multi-loo The term element and function are quite interchangeable in many instances. The output from the Filter is then fed to Sample and Hold (S/H)circuit. However, increasing the number of bits of A/D converter also affects the selection of processor. -Working & Types of UPS Explained. By contrast, an electromechanical protective relay converts the voltages and currents to magnetic and electric forces and torques that press against spring tensions in the relay. Some … Digital/numerical relays provide a front panel display, or display on a terminal through a communication interface. Multiplexer and Analog to digital converter 5. Memory 4. In this work the over current digital/numerical relay is explained with the simulink results and analysis. The Hardware part is briefly described below. 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. The distinction between digital and numerical relays is particular to Protection. See also: relay. No re-wiring is required. CPU 3. In a digital/numeric relay, many functions are implemented by the microprocessor programming. Numerical Relays are device in which measured electrical quantities are sequentially sampled and then converted into numerical data which are mathematically or logically processed to take decision for issuing trip command. If a virtual digital CCVT was designed in numerical distance relay and the output current of CT was input to virtual digital CCVT, the influence of CCVT transient of distance relays can be reduced. In distribution applications, the replacement by the digital relay proceeded a bit more slowly. The relay has less overloading capacity. The Hardware part is … The ECOFIT 50/51 Plug and Protect numerical relay is a direct replacement for many GE IAC and IFC relays that are still in service today. McLaren was the first to propose the concept of Open System Relaying, where different relay functions can be obtained from the same hardware just by modifying microprocessor programming [3]. It is also called numerical relay. Numerical Relays embedded with Digital Signal Processor (DSP) can be used to protect the system components as they can perform complex processing faster with … The timing of pulse can be changed by the user. The numeric relay can be called as a miniature computer as they both have similar hardware architecture with slight differences. The sampled data is then passed through a low pass filter that numerically removes the frequency content that is above the fundamental frequency of interest (i.e., nominal system frequency), and uses Fourier transform algorithms to extract the fundamental frequency magnitude and angle. Digital Input / Communication Module: Numerical Relays are provided with serial and parallel ports for the interconnection with control and communication system of the substation. An op-amp and comparator is used to create a DC that rises when a trip point is reached. Scope. [2] George conceived of it in his Master's Thesis in 1967–68 at Newark College of Engineering. A digital protective relay may also be called a "numeric protective relay". Numerical relays are natural developments of digital relays due to advances in technology. A typical Numerical Relay can store as much as 520 Events and 50 Disturbances. The term ‘static’ implies that the relay has no moving mechanical parts in it. ROM is also needed for storing Event and Disturbance data. If a fault condition is detected, output contacts operate to trip the associated circuit breaker(s). While numerical relay is in compact size and use indication on LCD for relay activation. Memory:Memory is of two types. More advanced analysis can be used to determine phase angles, power, reactive power, impedance, waveform distortion, and other complex quantities. PAC-E Series for Numerical Protection Relay have 3 types of relay which is a microprocessor-based numerical protection relay designed for the management and protection of a distribution feeder. Digital input/Communication module Input Module The Power system operates with analog parameters. Actually, a relay is nothing but a combination of one or more open or closed contacts. Few of the differences between conventional (electromechanical) and solid state (digital / numerical) relays can be highlighted as below: An electromagnetic relay is a switch that is turned on and off by a magnetic field. Numerical relays are classified broadly into four different types as Overcurrent relays, Distance relays, Directional relays and Differential relays depending upon their applications. RAM serves for the purpose of retaining the input data to the Relay and processing the data during the compilation of algorithm. A good design guideline is to choose a processor with double the number of bits of A/D converter. Most of us are aware of Electromagnetic Relays and Static Relays but most us may not be well acquainted with Numerical Relay. Digital And Smart Grid Enterprises - Offering SIEMENS 7SR1004 Over Current Protection Numerical Relays, ओवरकरंट रिले in Navi Mumbai, Maharashtra. Numerical relays use digital signal processors (DSP) cards, which contain dedicated microprocessors especially designed to perform digital signal processing. Delay in operation: Easily provided Hardware for Metering: In principle, the hardware setup discussed above can be used for both measurement and protection function. the number of bits in A/D converter. Input Module: The analog single from the Power System is stepped down using Current Transformer and Potential Transformer and then fed to the Numerical Relay using low pass filter. First … Author: T.S.M. Numerical Relays are basically Digital Relays for which manufacturers have developed specified hardware which can be used in conjunction with suitable Software o meet different protection needs. 2000 A. Currently, the industry is introducing digital/numerical relays as they provide sub-station protection, control and communication, and the recording of disturbances and faults. 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 implement different types of protection scheme. The logic is user-configurable and can vary from simply changing front panel switches or moving of circuit board jumpers to accessing the relay's internal parameter setting webpage via communications link on another computer hundreds of kilometers away. For simplicity on one-line diagrams, the protection function is usually identified by an ANSI device number. There are also more specialized relays, for example, for line differential protection. As a result, the relay is capable of performing complex digital signal processing to detect fault faster and more accurately compared to previous relay technology. [1] II. Digital output contacts of Numerical Relays are used for wiring with the Auxiliary Relays to extend tripping command to the Circuit Breaker. Protective elements refer to the overall logic surrounding the electrical condition that is being monitored. For instance, in some time overcurrent solid state relays, the incoming AC current is first converted into a small signal AC value, then the AC is fed into a rectifier and filter that converts the AC to a DC value proportionate to the AC waveform. Compared to the Thus, precaution should be taken for avoiding the damages through voltage spikes. 2.2. The high powered analog signals are stepped down with current tran… It is very easy to provide electrical isolation between the coil that creates the magnetic field and the switch contacts. Get best price and read about company. Numerical relay is actually the digital relay as a unit for which manufacturers has developed standardized hardware, which can be used in conjunction with suitably developed software to meet variety of production requirements and applications. It was commissioned in service on a 230kV transmission line at PG&E's Tesla substation in February 1971 and was in service for six years. Write the python code for the implementation of numerical overcurrent relay and numerical distance relay using Analog to digital converter. Get best price and read about company. Book Description: The protective relay industry has kept pace with the technological advancements in the field. El. Low pass filter is incorporated in the input module to eliminate any noise single induced in the line due to corona or induction effect of nearby high voltage line. Communication ports may include RS232/RS485 or Ethernet (copper or fibre-optic). Video that explains overcurrent protection testing: This page was last edited on 28 December 2020, at 03:33. In a solid-state relay, the incoming voltage and current wave-forms are monitored by analog circuits, not recorded or digitized. Protection algorithms are a set of logic equations in part designed by the protection engineer, and in part designed by the relay manufacturer. ... Sepam™ Digital Relays. In transmission line and generator protection, by the mid-1990s the digital relay had nearly replaced the solid state and electro-mechanical relay in new construction. Make: Projects is your all in one workplace for STEM minds to share ideas, take action and solve problems, big and small! The protective relay industry has kept pace with the technological advancements in the field. (1 relay can be used as over current only for under voltage we use another relay). SEL, AREVA, and ABB Group's were early forerunners making some of the early market advances in the arena, but the arena has become crowded today with many manufacturers. Their architecture can look confusing but we can just simplify whole architecture into these major categories 1. The use of digital multifunction relays and their proper integration into power system is an important element of this process. Any one numeric relay may implement one or all of these functions. Numeric relays, on the other hand, are programmable relays where the characteristics and behavior can be programmed. In principle, the hardware setup discussed above can be used for both measurement and protection function. Among the protection relays there are some used for general feeder protection (protection against over-current) and as back-up protection. It is also called numerical relay. This ensures that truncation and numerical precision problems associated with finite precision arithmetic do not cause significant loss of accuracy. In case more than one analog quantity is to be converted into digital form, Multiplexer is used for selecting any analog input at a time to convert into digital form. Electromechanical relays are used dominantly in the electrical industry due to simple working and installation procedure. CPU: CPU stand for Central Processing Unit which is responsible for the processing of protection algorithms and digital filtering. Brief Introduction about Relay: RELAY: A Relay is a protection device that senses the fault in the circuit and gives a trip signal to the Circuit Breaker to isolate the faulty circuit. Get contact details and address| ID: 21456244355 Numerical Relays are equipped with software to communicate with external device to program to Relay or one can program by navigating through the Relay Menu. Input Module 2. The generalized numerical relay consists of a minimum set of hardware modules and … Numerical Relays are basically Digital Relays for which manufacturers have developed specified hardware which can be used in conjunction with suitable Software o meet different protection needs. However, during the change from one setting to another, loss of information can take place. In 1971 M. Ramamoorty was the first to describe [8] calculation of impedance for distance protection using discrete Fourier analysis. [6] In 2017 George received the IEEE Halperin Electric Transmission and Distribution Award. More complex digital relays will have metering and communication protocol ports, allowing the relay to become an element in a SCADA system. A big difference between conventional electromechanical and static relays is how the relays are wired. 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. Types of protection relays are mainly based on their characteristic, logic, on actuating parameter and operation mechanism. 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