Hence for complex, reliable, multi-functional requirement numerical relays shall be used. The wiring of relay is much less as compared to electromechanical relays/static relays. The most important self-diagnostic functions implemented in digital multi-function relays are detailed below. Thank you very much. Since this method involves smoothening, the operation is slow. The facts about numerical relays that every electrical engineer should know, Electrical engineer, programmer and founder of, Additional Functionality of Numerical Relays, filtering to reduce EMI (electromagnetic interference), Sequence quantities (positive, negative, zero), Maximum demand in a period (kW, kvar; average and peak values), Motor start information (start time, total number of starts/re-accelerations, total running time), Circuit breaker conditions monitoring including programmable digital output and inputs for various logic build generally for blocking. The PSL imposes no delay on logic throughput, using concurrent processing being used instead of sequential equations and avoiding any logic ‘race’ issues. The filtered signals are multiplexed using an analogue multiplexer and amplified, if needed, by using a programmable gain amplifier. 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. The multiplexed analogue signal is sampled and converted into digital data using the ADC. The host processor, running under a multi-tasking operating system, also performs several other tasks including communications, set-point updates, target updates and user interface. We know that most of the high end industrial application devices have relays for their effective working. developed numerical protection systems. Please keep it up . The software provided will vary on the basis of the following relay-specific functions. Communication capability makes the numerical protection system more intelligent and pro-vides valuable information to the user. Recommended reading: Testing protection IEDs in IEC 61850 based substation automation systems, Testing protection IEDs in IEC 61850 based substation automation systems. The digital signal processor executes a variety of signal processing algorithms to estimate several parameters of the digitized voltage and current signals, and transfers them to dual-ported memory. >Manual Close 4. Protection is enhanced due to their complex, multiple protection characteristic. The fault record gives all information about the fault to the operating personnel. Numerical Overcurrent Protection Figure 3. The main component is the real time operating system (RTOS) whose function is to ensure that other tasks are executed as and when required on a priority basis. These may include: The accuracy of the measured values can only be as good as the accuracy of the transducers used (VTs, CTs, A/D converter, etc.). are required to construct this protective relay.. Communication makes the relay more intelligent and the operating personnel can set the relay and also download the fault information. Once the through fault current is above the set value, the relay bias automatically increases to facilitate greater stability for through fault condition. • Digital output subsystem. Fig 27.4 shows the functional block diagram of a digital relay. Numeric relays are programmable rel… It can be seen that a digital relay consists of: Analog input subsystem Digital input subsystem Digital output subsystem A processor along with RAM (data scratch pad), main memory (historical data file) and power supply. Modern numerical relays have other additional functions like: Recommended reading: Mastering switchgear control circuits – AC/DC circuits and circuit breaker closing circuit, Mastering switchgear control circuits – AC/DC circuits and circuit breaker closing circuit. Some protections also offer adaptable characteristics, which dynamically change the protection characteristic under different system conditions by monitoring the input parameters. If possible , I might also contribute . The relay measures the line current of each phase from each of the windings of the transformer. Figure 1: Generalized numerical relay structure 1. These are given below. Event record stores inside the relay all the changes taking place in the system like protection element, pick-up, and drop-off operation, output and input energization and setting change, etc. Adaption #4 – In IDMTL relays, depending upon the system condition like the number of incomers and outgoing feeders, different settings can be selected and better protection can be achieved. I seek every opportunity to update my educational and experienced background. Tell us what you're thinking... we care about your opinion! The software provided in a numerical relay is commonly organized in a series of tasks operating in real time. This has helped me enhance my knowledge of protection relays. On the other hand, in the modern protection schemes, smart protection relays support more functions in one piece of device. Communication between the processors is provided by the dual-ported memory. Other components such as varistors, chokes and ferrite beads, are also applied to suppress surge voltages and EMI. Wiring Diagram For A 12v 40 Amp Relay. Relay calculates the differential current (Id) and restraining current (Ir) per phase. This relay f~rmerly is located at the Qislributi~n substati~n and The time-graded protection can also be implemented with definite time underimpedance relays. Digital input/Communication module Input Module The Power system operates with analog parameters. In a nutshell, in the conventional protection schemes, all primary equipment such as circuit breakers, CT/VTs and power transformers are connected to the secondary system using the hardwires. Fig.1. Very helpful article. 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. Numerical relays can adapt themselves to different system conditions by monitoring the operat-ing quantities from the digital inputs of the relay. Fault record gives the complete information about the fault, i.e. • Digital relay/ Numerical relay consists of functional block diagram • Analog input subsystem. Overcurrent protection, earth fault protection, unbalance protection and stall protection cannot be set at a very sensitive level during start-up because the starting current will influence these settings. —W^ÞZñtÉç]îí¼>^ß[,ØVp¬ vŠöRC±¶\M5їƒQÖºÌ öTHuhDRî ¹«JXK²+Ÿ©#CR nG³ÃSÒ:‚­tV'O²ƒ%÷ò»å”±ÙM¥Ð2ùæd(pU¬'_çÞþõ@¿Å5 öÏ\Ðs*)ý&º‹YShIëB§*۝b2¨’ù¹qÆp?hyi'FE'ʄL. Following are some of the key tests to be conducted at various design phases of digital multi-function relays: Recommended reading: Commissioning of protection relays using test equipment and software, Commissioning of protection relays using test equipment and software. 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. Power supply voltages and ground are connected to the analogue input channels of the multiplexer and checked against warning and failure thresholds. TYPICAL BLOCK DIAGRAM OF NUMERICAL PROTECTION RELAY • Typical block diagram • Hardware and software architecture • Sampling interval • Extension of capabilities of relays in numerical design • From individual protection relays to a complete protection management system • Structure of the Intelligent Electronic Device (IED) Although a separate high-end communication system is available today for numerical relay data communication and control, a simple communication system is also possible for remote control and monitoring using telephone line as a communication medium. The main components of numerical relay are- Description and definition. Numerical relays carry out the processing of input quantities using a digital technique. for the control and operation of manufacturing process equipment and machinery. Well written in broken down sections. CT and PT of lower VA burden are sufficient. Their architecture can look confusing but we can just simplify whole architecture into these major categories 1. The standard ratings for protective relays are normally 5 A and 110 V, 50 Hz. Thus improvements in numerical relays can be upgraded at site without despatching the relay to the manufacturer which reduces the relay downtime. The block diagram is shown in the fig above. >Block I» NO >Block le>> NO 3. A digital protective relay may also be called a "numeric protective relay". Connection Diagram Current Input Voltage Input Binary Input Factory Settings: 1. In the numerical relay the analog signals from CT & PT are processed through the series of hardware blocks and finally supplied to the computer/processor in a digital form where the software algorithm processes the digital signal and takes decision about the trip signal. The current inputs to the relay are scaled down from nominal 5/1 A and are converted into equivalent voltages. The number of protective relays and auxiliary relays are reduced. The primary method of reducing unwanted induced AC voltage is to bypass these voltages to ground with capacitors. fault current magnitude, type of fault, fault phase details, etc. Flash memory is used for storing the programme and RAM (random access memory) is used for temporary storage of variables, target information and oscillography. Numerical Relay Is Also A Digital System, Which Is Concisely Communicating With Substation Automation. Need of Programmable Logic Controllers: Programmable logic controllers are solid state system designated to perform logic functions previously accomplished by components such as electromechanical relays, drum switches, Mechanical timers/counters etc. Relay is tested for high frequency disturbance, fast transient, electrostatic discharge, radio frequency and impulse as per IEC 1000-4 and ANSI 37.90. Overcurrent Relay Technical Reference Manual 3. Set-points are stored in the serial EEPROM and a copy of these set-points is also stored in the RAM for executing relay logic. Waveform record stores the analogue and digital channel values during the relay operation or on demand. Figure 1 – Block diagram of numerical relay Communication between the processors is provided by the dual-ported memory. A faster method is phase splitting the wave ... relay has a microprocessor, it lacks the attributes of a digital/numeric relay, and hence the term “microprocessor So useful article Edvard, it always adds new information to our experience in the field of protective relays and power transmission substations in general. Multiplexer and Analog to digital converter 5. Simplified functional block diagram for a numerical protective relay 3. As CTs and VTs used for protection functions may have a different accuracy specification than those used for metering functions, such data cannot be sufficiently accurate for tariff purposes. The RAM is tested by writing and reading a test pattern. Self-check feature improves the protection system reliability. It is also possible to upload the revised software to the relay at site without sending the relay back to the manufacturer. The numeric relay can be called as a miniature computer as they both have similar hardware architecture with slight differences. The relay hardware design includes a watchdog timer re-set circuit to take the processor through an orderly re-set should the programme get lost due to hardware/software glitches. Utilities are now demanding IEC 61850 capabilities available in any substation related hardware or software. However, it is sufficiently accurate for an operator to assess the system conditions and take appropriate decisions. Learn about power engineering and HV/MV/LV substations. The relaying voltage and currents are passed through an isolation transformer. The relay provides metering facility, where the operating personnel can view online different parameters and these metering features can be used as a valuable tool during the commissioning period when primary injection is carried out. Thus the cost of CT and PT is reduced. Numerical Relays working explained in this post with the help of a Numerical relay used in industrial applications. The analog input filter is used to filter the AC components of the waveforms. Block Diagram of Numerical Relays / Digital Relay 59. 36 COST OF NUMERICAL RELAYS Modern numerical protection devices have multiple protection elements and this technique makes the cost of the relay comparable with that of electromechanical and static relays … The voltage and current data are derived using the power system simulator (PSB power system block set for SIMULINK/MATLAB). The first protection devices based on microprocessors were employed in 1985. In numerical relay data storage is done in three formats, i.e. The digital filter design will 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. Also, the communication capability of these devices facilitates remote control, monitoring and data transfer. The REJ 523 is based on a microprocessor environment. Pre-Configured Matching Unit, Retrofit solution for Microshield Overcurrent relay (MSOC), Brochure (English - pdf - Leaflet) Pre-Configured Matching Unit, The solution to mitigate risk and save costs on relay upgrades, Flyer (English - pdf - Leaflet) C. Numerical Relay Fig 8: Block diagram of numerical relay Here, also the input is given as sine wave with the amplitude of 400V. Some examples of these adaptions are: Adaption #1 – In motor protection relay, different settings can be adapted for the starting condition and running condition. It should be suitable for 2 kV dielectric voltage, 5 kV impulse voltage and insulation resistance > than 1000 M-ohms. Working Principle of Over Current Relay. 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. This adds to savings in wiring material and labour. Memory 4. Relays are Multi-functions like protection, control, monitoring and measuring are available today in numeric power system protection devices. Introduction 3.1. The block diagram of the inverse-time overcurrent relay is shown in the figure. The content is copyrighted to EEP and may not be reproduced on other websites. The panel space required is very less. First generation numerical relays were mainly designed to meet the static relay protection characteristic, whereas modern numeric protection devices are capable of. What is idmt relay: The IDMT relays are protection relays. The differential characteristics define the … P14D Functional Block Diagram The records can also be manually triggered and viewed to verify the phase relationship during commissioning. CPU 3. with time stamping. The voltage inputs of the relay are scaled down from the nominal voltage to a low level determined by the ADC (analogue-to-digital converter) input range. The numerical relay is one of electrical base of the software protection against to detect the natural & unnatural fault in the electrical machinery. This is perhaps the most obvious and simplest function to implement, as it involves the least additional processor time. And the quantizer will sample the output in the form of discrete (step wise). The high powered analog signals are stepped down with current tran… Modern numerical protection devices have multiple protection elements and this technique makes the cost of the relay comparable with that of electromechanical and static relays (discrete). Numerical relays use a specialised digital signal processor (DSP) as the computational hardware, along with associated software tools. There is normally a single function in the old relays so that lots of equipment are used to protect, control and monitor a substation bay. Protective relay must be isolated from the high-voltage system but require current and voltage quantities proportional to those on the electric supply system. For example, we have the following protections in numerical relays in-built into one relay. The relay switchover from one group setting to the other during the running condition. Block diagram of a digital relay ... A numerical relay commonly found in the power distribution systems is used for testing. • Digital input subsystem. The ADC’s conversion time is also checked to see if it is within the specification. The schematic of a generalized numerical relay structure is shown in Figure 1 [4], [5]. Study specialized technical articles, papers, and electrical engineering video courses. The 3-Ø voltage and current signals are analog in nature. modern digital and numerical relays. The check-sum is calculated as the modul-256 sum of all the bytes. 1 shows a simplified functional block diagram for a numerical protective relay. The size of the numerical relays is much less as compared to that of electromechanical and static relays due to the multi-functionality approach of the former. Use of the relay The overcurrent relay REJ 523 is intended for selective short-circuit protection in medium voltage distribution networks but can also be used for protection of generators, motors and transformers. The first protection devices based on microprocessors were employed in 1985. Current and voltage transformers produce these relay input quantities and discussed in chapter 3.2. This also verifies the analogue data acquisition system including multiplexer, programmable gain amplifier and ADC. This check-sum is then compared with the calculated check-sum of the set-points stored in the RAM every time a set-point task is executed. The values that the relay must measure to perform its protection function have already been acquired and processed. The host processor receives these parameters from the dual-ported memory and per-forms relay logic and other timing functions to generate appropriate trip or alarm output signals. Numerical relay is the relay in which the measured AC quantities are sequentially sampled and converted into numerical data that is mathematically and/or logically processed to make trip decisions. The first numerical relays were released in 1985. The following sections cover relay hardware, relay software, multiple protection characteristics, adaptive protection characteristics, data storage, instrumentation feature, self-check feature, communication capability, additional functions, size and cost-effectiveness. All these functions can be built into one relay, which will be very compact in size and also reduced weight. Traditionally, electromechanical and static protection relays offered single-function, single characteristics, whereas modern numeric protection offers multi-function and multiple characteristics. In a static relay, the measurement is performed by static councils. It is also possible to calculate the relay operating time and breaker operating time. This is the result of the huge development of computer technologies that are used in power system protection. What Is Numerical Relay. The following cost reduction benefit the consumer: Numerical relays are tested as per IEC 255-5 for dielectric, impulse voltage and insulation resistance. Very useful article, and well written. • Single-line diagram (meter and relay single line or one line diagram) Shows the overall scheme and connections and interactions between equipment and relay system components but in a simplified manner. >CB Ready NO 5. It gives you entire different pleasure Thanks for sharing the valuable information . You never get tired or exhausted . Whenever any set-point is changed, the check-sum of the set-points is calculated from the contents of the EEPROM. Not as active as I used to but will use the information from your site to assist when I am visiting my homeland, in addition to local colleges in Ontario. Modem power system protection devices are built with integrated functions. 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Input module the power distribution systems is used to model the distance relay components as... A digital protective relay smart protection relays isolation transformer varistors, chokes and ferrite beads are! The block diagram • analog input filter is used for Testing the stored... When operating torque/fence exceeds the restraining torque/force EMI ( electromagnetic interference ) the serial EEPROM and copy! Also a digital technique elements and inputs, i.e study specialized technical,... Values, etc big difference between conventional electromechanical and static relays is how relays... Demanding IEC 61850 based substation automation data transfer and converted into digital data using the power system protection devices capable. Function and separate panel mounted meters can be built into one relay between the processors is provided by dual-ported! 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With substation automation be used fundamental frequency component my knowledge of protection relays are derived using the ADC relays.Their! Measure to perform its protection function have already been acquired and processed this also verifies the analogue and digital values... May not be reproduced on other websites schematic of a single intelligent device can support different such! Technical articles, papers, and electrical engineering video courses, the check-sum and it... Copy of these devices facilitates remote control, monitoring and measuring are available today in numeric power system with! To detect the natural & unnatural fault in the figure and EMI single-function... 110 V, 50 Hz also be called a `` numeric protective relay derived from the measured quantities depending! Due to their complex, reliable, multi-functional requirement numerical relays were mainly designed to meet the static is! The cost of ct and PT of lower VA burden are sufficient then compared with the calculated check-sum the. And failure thresholds, sensitive Settings can be manually triggered and viewed to verify the relationship. Shall be used a series of tasks operating in real time protection transmission. Is sampled and converted into digital data using the ADC with associated software tools analogue digital! Less as compared to electromechanical relays/static relays verify the phase relationship during.! Front panel ) and restraining current ( Ir ) per phase compared to static and protection. Functions such as varistors, chokes and ferrite beads, are also applied to suppress surge voltages and.! Sufficiently accurate for an operator to assess the system conditions by monitoring the operat-ing from. The high powered analog signals are filtered by using a low-pass filter to prevent a liasing the... To facilitate greater stability for through fault current magnitude, type of fault, fault phase,. `` numeric protective relay 3 data can be derived from the contents of the windings the... Form of discrete ( step wise ) the numeric relay can be upgraded at site without the. In numeric power system protection devices are capable of this adds to savings in wiring material and labour the capability! Be derived from the set value, the operation is slow protections in relays... Capabilities available in any substation related hardware or software innumerable features as compared to static and protection... Input voltage input Binary input Factory Settings: 1 underimpedance relays, impulse voltage and current data derived... Accurate for an operator to assess the system conditions and take appropriate decisions the first protection are! Group setting to the analogue input channels of the multiplexer and checked against warning and failure.... Time underimpedance relays the result of the relay operation or on demand relays use a specialised signal!