• 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. Self-diagnostics is one of the most important features of numerical relays; it was not available in either electromechanical or static relay design. 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 Numerical Relays working explained in this post with the help of a Numerical relay used in industrial applications. The values that the relay must measure to perform its protection function have already been acquired and processed. The voltage and current data are derived using the power system simulator (PSB power system block set for SIMULINK/MATLAB). Their architecture can look confusing but we can just simplify whole architecture into these major categories 1. VT/CT supervision. The relay has 32 PSL timers could be conveniently configured in PSL, setting or from the relay front panel. Modem power system protection devices are built with integrated functions. • A processor along with RAM (data scratch pad), main memory (historical data file) and power supply. 1 shows a simplified functional block diagram for a numerical protective relay. 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 … comparators – Block diagram of Numerical relays – Overcurrent protection, transformer differential protection, distant protection of transmission lines. modern digital and numerical relays. are required to construct this protective relay.. All the events are time-stamped. Some relays can also give the energy meter function. Recommended reading: Testing protection IEDs in IEC 61850 based substation automation systems, Testing protection IEDs in IEC 61850 based substation automation systems. So useful article Edvard, it always adds new information to our experience in the field of protective relays and power transmission substations in general. 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. These are given below. Numerical relays carry out the processing of input quantities using a digital technique. The current inputs to the relay are scaled down from nominal 5/1 A and are converted into equivalent voltages. The block diagram of the inverse-time overcurrent relay is shown in the figure. Communication between the processors is provided by the dual-ported memory. In simple Inverse definite minimum time lag (IDMTL) overcurrent and earth fault relays, multiple characteristics like NI, VI, El, LTI and DTL characteristics are available in relay and the required characteristics can be selected at site. So a single intelligent device can support different functions such as protection, control, metering and fault recording. The schematic of a generalized numerical relay structure is shown in Figure 1 [4], [5]. The flash ROM contents are checked by calculating the check-sum and comparing it with the pre-computed and stored check-sum. Tell us what you're thinking... we care about your opinion! This has helped me enhance my knowledge of protection relays. The analogue signal inputs (voltage and current), contact status inputs and communication circuits are conditioned and protected to withstand the harsh electrical and environmental conditions of the sub-station and power plant. This also verifies the analogue data acquisition system including multiplexer, programmable gain amplifier and ADC. The measuring principles and techniques of conventional relays (electromechanical and static) are fewer than those of the numerical technique, which can differ in many aspects like the type of protection algorithm used, sampling, signal processing, hardware selection, software discipline, etc. The numeric relay can be called as a miniature computer as they both have similar hardware architecture with slight differences. 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. 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. 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. Numeric relays, on the other hand, are programmable relays where the characteristics and behavior can be programmed. 60. Fault record gives the complete information about the fault, i.e. 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 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. 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. Conventional electromechanical and static relays are hard wired relays.Their wiring is fixed, only their setting can be manually changed. Simplified functional block diagram for a numerical protective relay 3. 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. CPU 3. Also in motor protection relays, additional information pertaining to positive sequence, negative sequence, equivalent current and difference current (between phases) is available. 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. Introduction 3.1. This adds to savings in wiring material and labour. A digital protective relay may also be called a "numeric protective relay". Thank you very much. Fig.1. Waveform record stores the analogue and digital channel values during the relay operation or on demand. The processed data can be accessed through the relay communication port. Relay calculates the differential current (Id) and restraining current (Ir) per phase. Relays are The filtered signals are multiplexed using an analogue multiplexer and amplified, if needed, by using a programmable gain amplifier. Thank you Edward. Study specialized technical articles, papers, and electrical engineering video courses. The fault record gives all information about the fault to the operating personnel. If possible , I might also contribute . In a static relay, the measurement is performed by static councils. The numerical relay is one of electrical base of the software protection against to detect the natural & unnatural fault in the electrical machinery. The standard ratings for protective relays are normally 5 A and 110 V, 50 Hz. The software provided in a numerical relay is commonly organized in a series of tasks operating in real time. The RAM is tested by writing and reading a test pattern. developed numerical protection systems. The check-sum is calculated as the modul-256 sum of all the bytes. What Is Numerical Relay. JND 040 provides differential protection for power transformer. 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. 2 Protection installations – principles 2.1 Operational block diagram of the protection installations PI and EP form together an automatic protection system, which is an automatic system in open circuit. Connection Diagram Current Input Voltage Input Binary Input Factory Settings: 1. 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. I seek every opportunity to update my educational and experienced background. The REJ 523 is based on a microprocessor environment. Also, the communication capability of these devices facilitates remote control, monitoring and data transfer. 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. For example, we have the following protections in numerical relays in-built into one 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. The software provided will vary on the basis of the following relay-specific functions. Memory 4. Figure 1: Generalized numerical relay structure 1. Once the through fault current is above the set value, the relay bias automatically increases to facilitate greater stability for through fault condition. From the set of possible values of the electric measures that feature the EP’s operation, PI Communication capability makes the numerical protection system more intelligent and pro-vides valuable information to the user. A relay is generally suitable for temperature as per IEC 255-6 for storage at -25°C to +70°C, and for operation at -25°C to +55°C. Fig. Flash memory is used for storing the programme and RAM (random access memory) is used for temporary storage of variables, target information and oscillography. In motor protection relay, the instrumentation mode can also display motor status, time to trip (during abnormal condition), time to start (if the protection is locked out), the last starting time, last starting current, positive, negative, difference current values, etc. However, it is sufficiently accurate for an operator to assess the system conditions and take appropriate decisions. Communication makes the relay more intelligent and the operating personnel can set the relay and also download the fault information. >CB Ready NO 5. 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. However, sensitive settings can be adapted for these protections during the running conditions of the motor. Traditionally, electromechanical and static protection relays offered single-function, single characteristics, whereas modern numeric protection offers multi-function and multiple characteristics. What is idmt relay: The IDMT relays are protection relays. The first protection devices based on microprocessors were employed in 1985. 1: Block Diagram of Numerical Relay Description: The microprocessor based relay works on numbers that quantities value of signal its works on numbers so that’s why it’s known as “Numerical Relay” In which fig CT/PT are used to sense the current and voltage of … These scaled signals are filtered by using a low-pass filter to prevent a liasing of the high-frequency components into the fundamental frequency component. fault current magnitude, type of fault, fault phase details, etc. Contact inputs and outputs, user inter-face (keyboard and liquid crystal display) and the serial communication ports (RS-232 and RS-485) are interfaced to the host processor. 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 relay switchover from one group setting to the other during the running condition. C. Numerical Relay Fig 8: Block diagram of numerical relay Here, also the input is given as sine wave with the amplitude of 400V. Hence for complex, reliable, multi-functional requirement numerical relays shall be used. Block Diagram of Numerical Relays / Digital Relay 59. The cost of the microprocessor and digital hardware is falling day by day and the end-user can get a cost benefit in numerical relays in terms of greater functionality at a reduced price. In numerical relay data storage is done in three formats, i.e. These records can also be converted into the ‘comtrade’ format, with which data can be played back into the relay using the digital test system. >LED reset NO 2. Multi-functions like protection, control, monitoring and measuring are available today in numeric power system protection devices. Numeric relays are programmable rel… >Block I» NO >Block le>> NO 3. The relay user can also make custom built logic by using internal elements and inputs, i.e. fault record, event record and waveform record. 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. 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). For example, it uses a single line to represent three phases (hence the … The pick-up of the relay is obtained by movement of the movable element in the relay. 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. Working Principle of Over Current Relay. Other components such as varistors, chokes and ferrite beads, are also applied to suppress surge voltages and EMI. First generation numerical relays were mainly designed to meet the static relay protection characteristic, whereas modern numeric protection devices are capable of. Some protections also offer adaptable characteristics, which dynamically change the protection characteristic under different system conditions by monitoring the input parameters. Numerical Overcurrent Protection Figure 3. Protection is enhanced due to their complex, multiple protection characteristic. Overcurrent and earth fault protection, and temperature protection. Description and definition. Whenever any set-point is changed, the check-sum of the set-points is calculated from the contents of the EEPROM. An iron core is surrounded by a control coil. 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. Interesting reading: Fault event reconstruction using data pulled from intelligent electronic devices (IEDs), Fault event reconstruction using data pulled from intelligent electronic devices (IEDs). 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. It is also possible to calculate the relay operating time and breaker operating time. Numerical relays are provided with a metering function and separate panel mounted meters can be eliminated. Current and voltage transformers produce these relay input quantities and discussed in chapter 3.2. The 3-Ø voltage and current signals are analog in nature. The high powered analog signals are stepped down with current tran… These records can also be fed to the harmonic analyzer software to find out the harmonic content in the fault quantities. The wiring of relay is much less as compared to electromechanical relays/static relays. Very helpful article. be used only in the Numerical relays. 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) 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. 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 is also possible to upload the revised software to the relay at site without sending the relay back to the manufacturer. Figure 4, shows the block diagram of the developed distance relay. This is perhaps the most obvious and simplest function to implement, as it involves the least additional processor time. Very useful article, and well written. Utilities are now demanding IEC 61850 capabilities available in any substation related hardware or software. Wiring Diagram For A 12v 40 Amp Relay. 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.). • Digital input subsystem. P14D Functional Block Diagram 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. It should be suitable for 2 kV dielectric voltage, 5 kV impulse voltage and insulation resistance > than 1000 M-ohms. A number of extra quantities can be derived from the measured quantities, depending upon the input signals available. IEC 61850 based solutions are now supporting a full interoperability between intelligent electronic devices (IED) from different manufactures. >Manual Close 4. 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. Knowledge is an ocean . Fig. It gives you entire different pleasure Thanks for sharing the valuable information . This is the result of the huge development of computer technologies that are used in power system protection. I am a retired Engineering Consultant. Please keep it up . 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. Figure 1 – Block diagram of numerical relay Communication between the processors is provided by the dual-ported memory. The number of protective relays and auxiliary relays are reduced. On the other hand, in the modern protection schemes, smart protection relays support more functions in one piece of device. —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. Since this method involves smoothening, the operation is slow. A simplified block diagram of a single input static relay is given in the above figure. 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. • Digital output subsystem. Self-check feature improves the protection system reliability. The electro-mechanical relay operates when operating torque/fence exceeds the restraining torque/force. For example, we have the following protections in numerical relays in-built into one relay. The differential characteristics define the … The following cost reduction benefit the consumer: Numerical relays are tested as per IEC 255-5 for dielectric, impulse voltage and insulation resistance. Numerical relays can adapt themselves to different system conditions by monitoring the operat-ing quantities from the digital inputs of the relay. Numerical Relay Is Also A Digital System, Which Is Concisely Communicating With Substation Automation. Recommended reading: IEC 61850 for digital substation automation systems, IEC 61850 for digital substation automation systems. Electromechanical and static relays have fixed wiring and the setting is manual. We know that most of the high end industrial application devices have relays for their effective working. CT and PT of lower VA burden are sufficient. You never get tired or exhausted . Relay is tested for high frequency disturbance, fast transient, electrostatic discharge, radio frequency and impulse as per IEC 1000-4 and ANSI 37.90. Block diagram of a digital relay ... A numerical relay commonly found in the power distribution systems is used for testing. And the quantizer will sample the output in the form of discrete (step wise). Adaption #2 – In transformer protection relay, the third slope is called the bias slope limit, which is used to afford greater stability and this can be achieved by monitoring the through fault current. Protective relay must be isolated from the high-voltage system but require current and voltage quantities proportional to those on the electric supply system. The PSL imposes no delay on logic throughput, using concurrent processing being used instead of sequential equations and avoiding any logic ‘race’ issues. Power supply voltages and ground are connected to the analogue input channels of the multiplexer and checked against warning and failure thresholds. Modern numerical protection devices offer innumerable features as compared to static and electromechanical protection system. A big difference between conventional electromechanical and static relays is how the relays are wired. All these functions can be built into one relay, which will be very compact in size and also reduced weight. Nice to see and read your articles . The first protection devices based on microprocessors were employed in 1985. Well written in broken down sections. The relay measures the line current of each phase from each of the windings of the transformer. • Digital relay/ Numerical relay consists of functional block diagram • Analog input subsystem. A relay is generally suitable for humidity as per IEC 68-2-3, for enclosure protection IP 52 as per IEC 529, for siesmic, shocks and bumps as per IEC 255-21 for Class 1 and for Class for vibration test as per IEC 255-21. Adaption #3 – In distance relays, for different system configurations like parallel feeder in, and parallel out and grounded, different settings can be adapted for this condition. Flash memory is used for storing the programme and RAM (random access memory) is used for temporary storage of … It is also called numerical relay. Block diagram of numerical relay have encouraged the design and development of microprocessor based protective relays are their economy, compactness, reliability, flexibility and improved performance over conventional relays. The analog input filter is used to filter the AC components of the waveforms. The ability to detect and correct a failure before the protection system has to operate is in contrast to the traditional protection system wherein a relay failure remains undetected until it fails to operate correctly during an event or until the next maintenance test. 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. The relaying voltage and currents are passed through an isolation transformer. 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Relays are tested as per IEC 255-5 for dielectric, impulse voltage current... Windings of the transformer dynamically change the protection characteristic under different system conditions and take appropriate decisions,! Data transfer dielectric voltage, 5 kV impulse voltage and current data are derived using the power system devices... The line current of each phase from each of the developed distance relay and failure.. Material and labour now supporting a full interoperability between intelligent electronic devices ( ). Stability for through fault condition are hard wired relays.Their wiring is fixed, only their can! Compared with the pre-computed and stored check-sum distant protection of transmission lines, reliable, multi-functional requirement numerical relays overcurrent..., papers, and electrical engineering video courses suitable for 2 kV voltage! Adc and digital channel values during the running conditions of the multiplexer and amplified, if needed, using. 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With RAM ( data scratch pad ), main memory ( historical data file ) and power supply must! Obvious and simplest block diagram of numerical relay to implement, as it involves the least additional processor time for executing relay.... Ct and PT is reduced, thereby resulting in further cost reduction benefit consumer... Categories 1 filtered by using internal elements and inputs, i.e are also applied to surge... Relay '' set-point is changed, the communication capability of these set-points is calculated as the modul-256 of. Simulator ( PSB power system block set for simulink/matlab ) through the relay are scaled down from nominal 5/1 and...