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. The first practical commercially available microprocessor based digital/numeric relay was made by Edmund O. Schweitzer, III in the early 1980s. Digital Input / Communication Module: Numerical Relays are provided with serial and parallel ports for the interconnection with control and communication system of the substation. Among the protection relays there are some used for general feeder protection (protection against over-current) and as back-up protection. 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. Numerical relays are the product of the advances in technology from digital relays. Though this relay has a microprocessor, it lacks the attributes of a digital/numeric relay, and hence the term "microprocessor relay" is not a clear term. digital relays, static relays or even electromechanical relays. Digital And Smart Grid Enterprises - Offering GE / Alstom P442 Numerical Distance Protection Relays, मोटर प्रोटेक्शन रिले, मोटर संरक्षण रिले in Navi Mumbai, Maharashtra. A Sample and Hold (S/H) circuit is used to keep the rapidly changing instantaneous value constant during the period of conversion for processing. The generalized numerical relay consists of a minimum set of hardware modules and … 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. Consider a hypothetical case where in maximum load current is 100 A and maximum fault current is 20 times this load current i.e. Input Module 2. RAM serves for the purpose of retaining the input data to the Relay and processing the data during the compilation of algorithm. Book Description: The protective relay industry has kept pace with the technological advancements in the field. Based on operation mechanism protection relay can be categorized as electromagnetic relay, static relay and mechanical relay. we respect your privacy and take protecting it seriously. 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. ROM is also needed for storing Event and Disturbance data. Output module provided in Numerical Relay is digital contacts which are actuated when a trip decision is taken by the CPU. Numerical relays use digital signal processors (DSP) cards, which contain dedicated microprocessors especially designed to perform digital signal processing. The distinction between digital and numerical relays is particular to Protection. In addition to the analog input, Numerical Relays are designed to accept digital input too. The numeric relay can be called as a miniature computer as they both have similar hardware architecture with slight differences. CPU: CPU stand for Central Processing Unit which is responsible for the processing of protection algorithms and digital filtering. He wrote the foreword for the PSRC tutorial on Computer Relaying produced in 1979. Author: T.S.M. The timing of pulse can be changed by the user. 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. Digital/Numerical Relays addresses the urgent based need of manufacturers and users adopting this latest technology. Numerical relays are natural developments of digital relays due to advances in technology. Actually, a relay is nothing but a combination of one or more open or closed contacts. 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. The static relay is more costly as compared to the electromagnetic relay. The working of the relay depends on the electrical components. Get contact details and address| ID: 21456244355 Let a 12 bit unipolar A/D converter be used for sampling current signal. Commentdocument.getElementById("comment").setAttribute( "id", "a9ee1e9e05a88d1af48e88d54409222f" );document.getElementById("j15d56cccb").setAttribute( "id", "comment" ); Subscribe to our mailing list and get interesting stuff and updates to your email inbox.  Such relays are also termed as microprocessor type protective relays. Alternatively, a variable gain amplifier can be used along with the A/D converter. -Working & Types of UPS Explained. At low currents, high gain setting is used and at high currents low gain setting is preferred.  II. El. Relays for different application ranges for overhead lines and cable feeders in distribution networks. 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. Event and Disturbance Recording is a must feature for a digital relay because these data are used for troubleshooting any event. – Construction and Working Principle, Binary Coded Decimal or BCD Number Explained, What is UPS? 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. 2000 A. ... Sepam™ Digital Relays. Electromechanical relays are used dominantly in the electrical industry due to simple working and installation procedure. 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. 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. 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. Based on type, medium voltage protection relays can be divided into electromechanical & static relays and digital & numerical relays. Make: Projects is your all in one workplace for STEM minds to share ideas, take action and solve problems, big and small! 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. A listing of device numbers is found at ANSI Device Numbers. Get best price and read about company. The first numerical relays were released in 1985. 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. 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. One solution is to increase resolution i.e. 2000 A. The continuing reduction in the cost and size of microprocessors, memory and I/O circuitry leads to a si… Scope. 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. First … Functions: 1 relay can perform various functions. Multiplexer and Analog to digital converter 5. This is used to display relay settings and real-time current/voltage values, etc. These output digital contacts are a pulse which is generated as a response signal. A Digital Relay comprises both Hardware and Software. The CPU accepts the input in digital form but the input from Current Transformer CT and Potential Transformer PT are analog in nature.  In 2017 George received the IEEE Halperin Electric Transmission and Distribution Award.  The award was for "pioneering development and practical demonstration of protective relaying of electric power systems with real-time digital computer techniques." 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 relay analyzes the resultant A/D converter outputs to determine if action is required under its protection algorithm(s). 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. In this work the over current digital/numerical relay is explained with the simulink results and analysis. 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. There are also more specialized relays, for example, for line differential protection. 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. 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. In distribution applications, the replacement by the digital relay proceeded a bit more slowly. Write the python code for the implementation of numerical overcurrent relay and numerical distance relay using Analog to digital converter. If a fault condition is detected, output contacts operate to trip the associated circuit breaker(s). The high powered analog signals are stepped down with current tran… Among different types of relays, the electromechanical relay has the lowest cost. For example, one may use 16 bit A/D converter in place of 12 bit A/D converter. More complex digital relays will have metering and communication protocol ports, allowing the relay to become an element in a SCADA system. Improved distance relays algorithm The output from the Filter is then fed to. This implies that resolution of A/D converter is 2000/(212-1)=0.488 A. The relay is capable of applying advanced logic. In this relays … 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. Numerical relays are classified broadly into four different types as Overcurrent relays, Distance relays, Directional relays and Differential relays depending upon their applications. The processing of numerical relays using DSP is also optimized for real-time signal processing applications . One is RAM (Random Access Memory) and ROM (Read Only Memory). Numerical Relays embedded with Digital Signal Processor (DSP) can be used to protect the system components as they can perform complex processing faster with … Digital input/Communication module Input Module The Power system operates with analog parameters. Generally, there are several different types of numerical protection relays.