These can then be printed or uploaded to the user’s database facilities. Irest= 0.3 x 0.5 = 0.15A (see point P on the restraint characteristic). The relay memory requires a certain minimum number of cycles of measured data to be stored for correct signal processing and detection of events. There may be other advantages such as different logic schemes required by different utilities that no longer need separate relay versions, or some hard-wired logic to implement, and all of these reduce the cost of manufacture. 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. The operation of these relays are independent of the fault current level rather the time delay provided to it to work. Many are downloadable. The CB position-switch outputs can be connected to the relay digital inputs and therefore provide the indication of state through the communications bus to a remote control centre. Learn new and interesting things. Instantaneous Relays – These relays employed after a small time duration from the incidence of the current or other quantity resulting in operation. In this paper, TMS320F28335 based Implementation of Numerical Relay is discussed. The general principle is the calculation of a level of negative sequence current that is inconsistent with the calculated value of negative sequence voltage. Now a day for - The cheapest method is to use a single A/D converter, preceded by a multiplexer to connect each of the input signals in turn to the converter. Electric FA Site.” The protection relay supports USB Type B connection. Types of protection relays are mainly based on their characteristic, logic, on actuating parameter and operation mechanism. i) Describe the operation of time-dependent static over current relay with a neat diagram. A Relay is an electromechanical device that can be used to make or break an electrical connection. A big difference between conventional electromechanical and static relays is how the relays are wired. They are functional replacements for electro-mechanical protective relays and may include many protection functions in one unit, as well as providing metering, communication, and self-test functions. 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. CPU: CPU stand for Central Processing Unit which is responsible for the processing of protection algorithms and digital filtering. Several extra quantities may be derived from the measured quantities, depending on the input signals available. The Hardware part is briefly described below. The current rating of the circuit in which relay is connected plays an important role in the operation of the relay. It detects the intolerable or undesirable condition with an assigned area and gives the commands to the circuit breaker to disconnect the affected area. Numerical relays are based on the use of microprocessors. For instance, an overcurrent relay at the receiving end of a transformer feeder could use the temperature inputs provided to monitor transformer winding temperature and provide alarm or trip facilities to the operator or upstream relay, eliminating the need for a separate winding temperature relay. This may obviate the need for duplicate relays to be fitted with some form of switching arrangement of the inputs and outputs depending on network configuration. OPERATION OF BASED IMPEDANCE PROTECTION NUMERICAL RELAY WITH STATCOM FACTS DEVICES Omar Noureldeen Faculty of Engineering, South Valley University, Qena, Egypt E-mail : omar_noureldeen@yahoo.com (Received May 21, 2009 Accepted July 13, 2009). It may be noted that that the transients occures in the system due to X?R ratio of the system and henec the transients vary based on the X/R ratio . However, considering the order of difference between current magnitudes in case of fault and load, there can be loss of accuracy during metering applications. Generally, there are several different types of numerical protection relays. Logic functions are well suited to implementation using microprocessors. It must work at high speed, use low voltages, yet be immune to conducted and radiated interference from the electrically noisy substation environment. The relay is an electromechanical switch used as a protecting device and also as a controlling device for various circuits, equipments, and electrical networks in a power system. Separate terminals are provided for the analog and digital inputs. This implies that resolution of A/D converter is 2000/(212-1)=0.488 A. However, increasing the number of bits of A/D converter also affects the selection of processor. If maintenance is not carried out within a predefined time or number of trips after maintenance is required, the CB can be arranged to trip and lockout or inhibit certain functions such as auto-reclose. The present protection technique used is unable to ensure selectivity and speedily operation for the faults appearing on the entire protected line. A thermal overload relay works in the principle of electro-thermal properties in a bimetallic strip. Finally, as well as tripping the CB as required under fault conditions, it can also be arranged for a digital output to be used for CB closure, so that separate CB close control circuits can be eliminated. The REJ 523 is based on a microprocessor environment. JNC 154 is a numerical local breaker backup relay. A big difference between conventional electromechanical and static relays is how the relays are wired. ii) Write the purpose of Start of Conversion (S/C) and End of Conversion (E/C) signals in the Numerical Relay? 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. 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. 1 Programmability of Numerical Relays: A Busbar Protection Relay Serves as a Traditional RTU Casper Labuschagne, Schweitzer Engineering Laboratories, Inc., Pullman, WA, USA Izak van der Merwe, Eskom Resources and Strategy Division, Cape Town, South Africa Abstract -- Numerical relays have revolutionized protection, control, metering, and communication in power systems. Relay. and Please clear how you considered TMS is 0.125 for low over current setting? The term "high speed" connotes operation in less than approximately 0.1 second and usually in 0.05 second or less. The small power relay has only one contacts, and the high power relay has two contacts for opening the switch. These operations are performed over the last samples of the sampled input signal. Practical experience indicates that numerical relays are as reliable as relays of earlier technologies. RAM serves for the purpose of retaining the input data to the Relay and processing the data during the compilation of algorithm. Differential relay :- A two-winding relay that operates when the difference between the currents / Voltage in the two windings reaches a predetermined value is called differential relays. The numerical relays are used for various types of protection and they are classified on the basis of characteristics, Logic, Actuation parameter and application. To use these features, the appropriate data must be entered into the relay’s memory and it is good practice to keep a backup copy. Top: Looking straight down, you can see the spring contacts on the left, the switch mechanism in the middle, and the electromagnet coil on the right. As the power of microprocessors continues to grow and pressure on operators to reduce costs continues, this trend will continue. 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. Nice Article.Relays are used to provide time delay functions. Sir please clear that,in Higher over current setting calculation,how you have considered relay plug setting is 2.5? Desired relaying characteristics can be obtained by using the same interface [810]. However, considering the order of difference between current magnitudes in case of fault and load, there can be loss of accuracy during metering applications. [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. A numerical relay can record all of these parameters and hence be configured to send an alarm when maintenance is due. A very high voltage develops across the relay circuit and the CT’s which can damage the insulation of CT’s, secondary wiring and relay. ABB has delivered numerical relays worldwide. The time is called operation time. of starts/reaccelerations, total running time, The different software versions in existence x the differences between each version. Page 1 Numerical Relay MELPRO Series MODEL CBV2 - A02S1 COC4 - A02S1 OPERATION MANUAL 1 / 47 JEP0-IL9537...; Page 2 - Safety precautions - Before installation, operation, maintenance, and inspection, please be sure to read this instruction manual and all other attached documents thoroughly in order to work safely with the equipment. 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’. However, if the DSP is overloaded it cannot complete the protection algorithm calculations in the required time and the protection function is slowed. A Sample and Hold (S/H) circuit is used to keep the rapidly changing instantaneous value constant during the period of conversion for processing. 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. Many numerical relays have the facility for time synchronisation from an external clock. The internal communications bus links the hardware and therefore is a critical component in the design. Every relay manufacturer with numerical relays will publish the transient dimensioning factor for their relay operation based on a range of X/R ratio . Numerical relays These relays are controlled by a smart controlling unit that continually monitors the grid parameters (such as voltages, currents, temperature, etc) and switches the appropriate relays in case fault conditions occur. Analogue signals are converted to digital form using an A/D converter. 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. To know the basic construction and internal parts of a relay, the following fig clearly shows an inside view of a relay.Lets discuss all of them one by one. General: The ADR241A is member of Ashida Numerical Relay family (Aditya Series) design to meet demand of low and medium switchgear control. This thesis describes the design and implementationof the PIC microcontroller based system for protecting 1KVA transformer from over current. This resolution may be inadequate for metering purposes. Numerical relays are able to improve the performance of the protection operation considerably. An input voltage is applied to the coil mechanism. It is placed in the motor circuit in such a way that the current to the motor flows through its poles. So relay is a switch which controls (open and close) circuits electromechanically. 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 first numerical relays were released in 1985. Let a 12 bit unipolar A/D converter be used for sampling current signal. Alternatively, 0.15A is the minimum diff current required for relay operation if the system loading is 0.5A (sec). For faster real time processing and more detailed analysis of waveforms, several DSPs can be run in parallel. L + R. STAB + R. relay) Metrosil required if V. P > 3kV Related Post: Solid State Relay (SSR) – Types of SSR Relays – Construction & Operation Construction of a Relay. The argument against putting many features into one piece of hardware centres on the issues of reliability and availability. Design & Principle NI 40/41 series relays are based on numerical microprocessor based technology. Consider a hypothetical case where in maximum load current is 100 A and maximum fault current is 20 times this load current i.e. A MATLAB model of a frequency relay was detailed before . Every relay manufacturer with numerical relays will publish the transient dimensioning factor for their relay operation based on a range of X/R ratio . The relation between time of operation and plug setting multiplier is plotted on a graph paper, and this is known as time/PSM graph. It works on the principle of an electromagnetic attraction. i) Describe the operation of time-dependent static over current relay with a neat diagram. Numerical relay are demand in a period ( kW, kVAr; average and peak values), Motor start information (start time, total no. Conf. Learn about power engineering and HV/MV/LV substations. The timing of pulse can be changed by the user. 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. However, during the change from one setting to another, loss of information can take place. View Numerical Relays PPTs online, safely and virus-free! Some of the new issues that must be addressed are as follows: Numerical relays perform their functions in software. Based on operation mechanism protection relay can be categorized as electromagnetic relay, static relay and mechanical relay. And the same relay can be used for analysing and monitoring multiple faults such as over current, over fluxing, different current and more. The ADR241A is a 3 OC and 1 EF relay with Instantaneous high set and programmable output to simplify feeder protection wiring. t. reactor protection and con trol, an exam ple of poss ible . We define this time as the minimum time of operation. 2000 A. restraint, while the fifth harmonic and d.c. component block relay operation. Get ideas for your own presentations. The digital signal processor (DSP) in a numerical relay normally can handle both the relay protection function calculations and general management of the relay such as HMI and I/O. Let a 12 bit unipolar A/D converter be used for sampling current signal. Proc. Most of us are aware of Electromagnetic Relays and Static Relays but most us may not be well acquainted with Numerical Relay. Hardware for Metering: In principle, the hardware setup discussed above can be used for both measurement and protection function. ROM is also needed for storing Event and Disturbance data. Electromechanical and static relays have fixed wiring and the setting is manual. Protection, Control and Operation of Transformer Using Numerical Relay 1. Numerical Relay; Classification based on Actuating Signals. A typical Numerical Relay can store as much as 520 Events and 50 Disturbances. Modern numerical relays will have comprehensive self monitoring to alert the user to any problems. 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. Now if IDIFF> 0.15A relay operation results. The relay algorithm is a set of mathematical operations implemented in a low level program (C/C++ compiler). The output of CT and PT are not suitable for static components so they are brought down to suitable level by auxiliary CT and PT. Page 1 Numerical Relay MELPRO Series MODEL CBV2 - A02S1 COC4 - A02S1 OPERATION MANUAL 1 / 47 JEP0-IL9537...; Page 2 - Safety precautions - Before installation, operation, maintenance, and inspection, please be sure to read this instruction manual and all other attached documents thoroughly in order to work safely with the equipment. Note that not all functions are found in a particular relay. 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. The relay is used to check the operation of feeder breaker and to trip all the breaker feeding fault in the event of feeder breaker fail to trip. It may be noted that that the transients occures in the system due to X?R ratio of the system and henec the transients vary based on the X/R ratio . These output digital contacts are a pulse which is generated as a response signal. Figure 1, Figure 2 and Figure 3 show typical numerical relays, while Figure 4 and Figure 5 show typical numerical relay boards. Relay Definition: The relay is the device that open or closes the contacts to cause the operation of the other electric control. 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 output from the Filter is then fed to Sample and Hold (S/H)circuit. 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. The protection relay no longer performs a basic protection function but is an integral and major part of a substation automation scheme. Numerical Relay; Classification based on Actuating Signals. Numerical relays are able to improve the performance of the protection operation considerably. 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. For example, with 16 bit A/D converter, 32 bit processor is the natural choice. This implies that resolution of A/D converter is 2000/(2, What is IGBT? In other words, the time of operation of the relay depends upon plug setting multiplier. The extra facilities in numerical relays may avoid the need for other measurement and control devices to be fitted in a substation. Mohit krushna pradhan says: June 26, 2016 at 3:40 pm. 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 implementation of logic in a relay is not new, as functions such as intertripping and auto-reclose require a certain amount of logic. It is also easier to customize a relay for a specific application, and eliminate other devices that would otherwise be required. [-09 – Rev01] Argus 7 Numerical Check Synchronism Relay Section 1 – Page 4 DESCRIPTION OF OPERATION Each of the status inputs can be programmed to … The alternative is to provide each input with a dedicated A/D converter and logic to ensure that all converters perform the measurement simultaneously. as Z or distance. 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. Reference // Network Protection & Automation Guide by Alstom Grid. ... ・16 kinds of operation time characteristics and wide setting range of time multiplier are available for overcurrent protection element. ), Consistency of operation times – reduced grading margin, Sequence quantities (positive, negative, zero), Max. Fault levels are significantly different on parts of the network that are energized under normal and emergency generation. Software problems are minimized by rigorous use of software design techniques and the ability to download updated software. A very important aspect of the relay operation is that it should be able to detect all fault conditions but should not trip due to spurious signals generated during power system transients. the overcurrent relay exceeds a setpoint amount, the relay operates with or without an intended time delay and trips the associated circuit breakers [13]. They use one or more digital signal processors (DSP) optimised for real time signal processing, running the mathematical algorithms for the protection functions. Principle of operation. It is now possible to implement a substation automation scheme using numerical relays as the main hardware provided at bay level. 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. It may be inconvenient to download the record immediately, so facilities may be provided to capture and store a number of disturbances. Balanced Beam Type : In this relay, the armature is fastened to a balanced beam. With the aid of suitable software held by a user, it may be possible to download the new software version instead of requiring a visit from a service engineer. Other software depends on the function of the relay, but can be generalized as follows: The relevant software algorithm is then applied. 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. 2000 A. The time delay is also known as operation time is computed from the protection algorithm embedded in the processor. Numerical relays are natural developments of digital relays due to advances in technology. They incorporate an extensive self-supervision system that continuously monitors the internal hardware and software of the relay. 57. It is placed in the motor circuit in such a way that the current to the motor flows through its poles. The first numerical relays were released in 1985. Failure to operate or even slow operation of the differential relay, in case of an actual internal fault, can have fatal consequences. The standard normally used is an IRIG-B or IEEE 1588 signal, which may be derived from several sources including a GPS satellite receiver. As the relay current does not increase further, there would not be any further reduction in time of operation in the relay. It consists of a flexible moving mechanical part which can be controlled electronically through an electromagnet, basically, a relay is just like a mechanical switch but you can control it with an electronic signal instead of manually turning it on or off. of Int. Additionally, the input signals must be amplitude limited to avoid them exceeding the measurement range, otherwise the waveform is clipped, introducing harmonics. The relay was tested under different frequency values with no attention to load shedding as described before for frequency relays. Therefore, a simple solution would be to keep metering and protection functionality separate. value of line to line fault current for the operation of the relay is: Reply. 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. Therefore, the time of operation of relay would vary as V/I i.e. April 28, 2018 at 3:28 pm . The content is copyrighted to EEP and may not be reproduced on other websites. 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. Typical functions that may be found in a numerical relay other than protection functions are described in this section. Alternatively, a variable gain amplifier can be used along with the A/D converter. ROM is used to store Software needed for the working of Relay. 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. TMS320F28335 is a floating point Digital Signal Controller (DSC). Function parameters are usually displayed on the front panel of the relay and through an external communications port. When the circuit of the relay senses the fault current, it energises the electromagnetic field which produces the temporary magnetic field. Hence, the characteristic is inverse in the initial part, which tends to a definite minimum operating time as the current becomes very high. In principle, the hardware setup discussed above can be used for both measurement and protection function. Range of operation of electromechanical relays is narrow as compared to numerical relay. A copy of the setting data (including user-defined logic schemes where used) can also be stored on the computer. Numerical relays are based on the use of microprocessors. Abstract— In this paper a prototype algorithm for Numerical Distance relay is developed in order to prevent mal-operation of relays when Current Transformer (CT) saturation occurs. System operators normally require knowledge of the state of all circuit breakers under their control. Distance Relay – In this relay operation depends on the ratio of the voltage to the current. Also the operator can program the relay remotely with a group of settings if required. This is often done using a Discrete Fourier Transform (DFT) and the result is magnitude and phase information for the selected quantity. Numerical relays perform many more functions than earlier generations of relays so testing them is more complex. Bottom: The same relay photographed from the front.Suppose you want to build an electronically operated coolingsystem that switches a fan on or off as your room temperaturechanges. Introduction and Architecture of Numerical Relay. The continuing reduction in the cost and size of microprocessors, memory and I/O circuitry leads to a si… relays that operate in a minimum time of approximately 0.1 second. Also numerical relays have functionality that previously required separate equipment. Modern numerical relay protection scheme offers multi-function and multiple characteristics, and other several advantages[9]. Dictionary says that relay means the act of passing something from one thing to another, the same meaning can be applied to this device because the signal received from one side of the device controls the switching operation on the other side. The first protection devices based on microprocessors were employed in 1985. There is no setting for maximum torque angle in numerical relays. It helps you. Digital output contacts of Numerical Relays are used for wiring with the Auxiliary Relays to extend tripping command to the Circuit Breaker. Traditional electromechanical and static protection relays offers single-function and single characteristics. Photo: Another look at relays. They are used to time the delay open and delay close of contacts. If only one or two phases are lost, the VT failure algorithm can be accomplished. 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