The values that the relay must measure to perform its protection function have already been acquired and processed. If suitable VTs are used, supervision of the VT/CT supplies can be made available. ), Communications built in (serial, Ethernet, teleprotection, etc. A relay’s ongoing performance is affected by the reliability and health of mechanical components (in the case of electromechanical relays), electronic circuits or components (static relays) and software (numerical relays). A big difference between conventional electromechanical and static relays is how the relays are wired. 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. Logic functions are well suited to implementation using microprocessors. They use one or more digital signal processors (DSP) optimised for real time signal processing, running the mathematical algorithms for the protection functions. Modern numerical relays will have comprehensive self monitoring to alert the user to any problems. If only one or two phases are lost, the VT failure algorithm can be accomplished. Using Protective Relay For Fighting Against Faults, The Good Old Electromechanical Protective Relay, The Solid State Relay (Static Relay) Overview, Flexibility and Reliability of Numerical Protection Relay. Scope Firstly the quantities of interest are determined from the information in the data samples. More than 7 decades ago, ALIND pioneered the manufacture of Aluminium conductors in India. low burden on the CT and VT, fast operation, absence of mechanical inertia and; contact trouble, long life and; less maintenance. A very important things that needs to be noted is that all the three types of these Relays(Considering Digital & Numerical to be one) are SCADA Compatible. The amount of data per numerical relay may be 10-100 times that of an equivalent electromechanical relay, to which must be added the possibility of user-defined logic functions. ), Auxiliary protection functions (broken conductor, negative sequence, etc. A transistor amplifier . System operators normally require knowledge of the state of all circuit breakers under their control. Disturbance records and data relating to energy consumption requires time tagging to serve any useful purpose. Traditional electromechanical and static protection relays offers single-function and single characteristics. Fault levels are significantly different on parts of the network that are energized under normal and emergency generation. 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. Most of us are aware of Electromagnetic Relays and Static Relays but most us may not be well acquainted with Numerical Relay. Good work Jignesh, But for El Mechanical Relay like CDD21 (Alstom) Aux. Numerical relays are natural developments of digital relays due to advances in technology. 4. Since our commencement in the year 1991, we, “Prok Devices Private Limited”, an ISO 9001:2008 certified company, are well-known in the industry as an eminent manufacturer, supplier and trader, engrossed in providing Electric Relay & Meter. 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. 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. Relay can be broadly classified on the basis of construction and application. 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. (for EM relay 100 mile ohm,other relay are 10 ohm). Depend upon gravitation and the value changes to the surrounding magnetic fields also. Numerical relays perform many more functions than earlier generations of relays so testing them is more complex. A solid state relay is composed of both static and electromechanical units in which the response is accomplished by the static units. ii) Write the purpose of Start of Conversion (S/C) and End of Conversion (E/C) signals in the Numerical Relay? this portal is very helpful to all the electrical engineering student as well as professor and technical engineer.It’s very nice and helpful for all in electrical engineering to get practical knowledge & idea very easily. In this relays transistors and … The implementation of logic in a relay is not new, as functions such as intertripping and auto-reclose require a certain amount of logic. Comparison of reliability and availability between the two methods is complex as inter-dependency of elements of an application provided by separate relay elements needs to be taken into account. As part of the process, Get access to premium HV/MV/LV technical articles, electrical engineering guides, research studies and much more! It is now possible to implement a substation automation scheme using numerical relays as the main hardware provided at bay level. This is perhaps the most obvious and simple function to implement, as it involves the least additional processor time. Electromechanical Relays The above diagram shows the schematic of an electromechanical 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. Numerical relays are the product of the advances in technology from digital relays. A big difference between conventional electromechanical and static relays is how the relays are wired. Many functions previously implemented in separate items of hardware can then be included in a single item. 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. T. S. Madhava Rao. Get access to premium HV/MV/LV technical articles, electrical engineering guides, research studies and much more! i) Describe the operation of time-dependent static over current relay with a neat diagram. This calculation is repeated for all of the quantities of interest. First generation numerical relays were mainly designed to meet the static relay protection characteristic, whereas modern numeric protection devices are capable of providing complete protection with added functions like control and monitoring. Numerical Relays working explained in this post with the help of a Numerical relay used in industrial applications. They use one or more digital signal processors (DSP) optimised for real time signal processing, running the mathematical algorithms for the protection functions. These can then be printed or uploaded to the user’s database facilities. It consists of one or more digital signal processors, some memory, digital and analogue input/output (I/O), and a power supply. Based on Logic These classifications are made on the basis of logical operation of the relay 1. The alternative is to provide each input with a dedicated A/D converter and logic to ensure that all converters perform the measurement simultaneously. setting can be manually changed. Functions: 1 relay can perform various functions. 2nd generation relays. 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. First generation numerical relays were mainly designed to meet the static relay protection A [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. VT supervision is made more complicated by the different conditions under which there may be no VT signal, some of which indicate VT failure and some occur because a power system fault has occurred. Such relays are also termed as microprocessor type protective relays. 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. However, if the DSP is overloaded it cannot complete the protection algorithm calculations in the required time and the protection function is slowed. The book is a thoroughly revised and updated second edition of a successful text. Numerical Relay . 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. Many numerical relays have the facility for time synchronisation from an external clock. 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. Numerical results show that different reliability measures have slightly different optimum altitudes and that decode-and-forward is better than amplify-and-forward. 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 … Power System Protection: Static Relays. It incorporates the latest developments in semiconductor technology and its applications to power system protection. can you advice the indian componies? ALIND -The Power Movers. First generation numerical relays were mainly designed to meet the static relay protection characteristic, whereas modern numeric protection devices are capable of providing complete protection with added functions like control and monitoring. Different configurations may require different relay settings to maintain the desired level of network protection. The extra facilities in numerical relays may avoid the need for other measurement and control devices to be fitted in a substation. Dear Jignesh A very well compiled work. Therefore solid state relays are also called as static relays. Each relay element is in software so with modular hardware the main signal processor can run a vast variety of relay elements. 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. directional IDMT O/L Relays and, Non-directional IDMT 3 Over Current and 1 Earth Fault relays, Non-directional IDMT 2 Over Current and 1 Earth Fault relays. This portal is very useful for Electrical Engineers. Historically, electromechanical and static relays have been provided with fixed plug settings applied to the relay. Although there is an internal clock, this is of limited accuracy and use of this clock to provide time information may cause problems if the disturbance record has to be correlated with similar records from other sources to obtain a complete picture of an event. Also, it requires continuous power supply. The frequency of sampling must be carefully considered, as the Nyquist criterion applies: If the sampling frequency is too low, aliasing of the input signal can occur (see Figure 8) so that high frequencies can appear as part of the signal in the frequency range of interest. The typical architecture of a numerical relay is shown in Figure 6. There value may vary with respect to temperature also. The static relay is more costly as compared to the electromagnetic relay. 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. Numerical relays are natural developments of digital relays due to advances in technology. Supply is not required and all the Numerical Relay are Multi function relays. As the power of microprocessors continues to grow and pressure on operators to reduce costs continues, this trend will continue. A different interface port for the Hot signals (with varying voltages) for the E&M and Static Relays while as a different Communication port for the Soft signals from the Numerical Relays. The introduction of numerical relays replaces some of the issues of previous generations of relays with new ones. The task of entering the data correctly into a numerical relay becomes a much more complex task than previously, which adds to the possibility of a mistake being made. This relay has to be installed straight only and away from magnetic field. Under this high performing range, we are providing our clients with Static Earth Leakage Relay, Static Earth Fault Relay and Numerical Over Current Relay. Tell us what you're thinking... we care about your opinion! 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. They use principle of electromagnetic principle. Function parameters are usually displayed on the front panel of the relay and through an external communications port. The distinction between digital and numerical relays is particular to Protection. Tata McGraw-Hill Education, 1989 - Electric power systems - 723 pages. The construction of the relay is easily affected by the surrounding interference. Powerful six-phase relay testing and more. Electromechanical and static relays have fixed wiring and the setting is manual. C. A transistor switch . Working Principle of Over Current Relay. Static relays possess the advantages of having. The continuing reduction in the cost and size of microprocessors, memory and I/O circuitry leads to a si… demand in a period ( kW, kVAr; average and peak values), Motor start information (start time, total no. Unfortunately, power systems change their topology due to operational reasons on a regular basis, such as supply from normal or emergency generation. For faster real time processing and more detailed analysis of waveforms, several DSPs can be run in parallel. CT supervision is carried out more easily. Numeric relays are programmable relays. The relay memory requires a certain minimum number of cycles of measured data to be stored for correct signal processing and detection of events. are required to construct this protective relay.. By organising the I/O on a set of plug-in printed circuit boards (PCBs), additional I/O up to the limits of the hardware  / software can be easily added. Best Information sir, We have China made Microprocessor based relay in hydro power projets, now we are finding alternative to same in Indian manufacturing relays. The distinction between digital and numerical relays is particular to Protection. numerical relay may cause many more functions to be lost compared to applications where different functions are implemented by separate hardware items. Study specialized technical articles and papers. B. 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 optimum altitude is investigated for both static and mobile UAVs. The first protection devices based on microprocessors were employed in 1985. Position of relay: Relay can be installed at any location and at any position. Numerical relays are the latest development in this area. 20% off code for Pro Plan: EEP2020. 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. 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. Where multiple processors are used, one of them is a general controller of the I/O, Human Machine Interface (HMI) and any associated logic while the others are dedicated to the protection relay algorithms. The content is copyrighted to EEP and may not be reproduced on other websites. Conventional electromechanical and static relays are hard wired relays.Their wiring is fixed, only their setting can be manually changed. Figure 2 shows cost comparison of numerical relay with electromechanical and static relay [1]. Keypad for numeric values, through computer, Circuit breaker Auxiliary switch “Normally open” (‘a’ contact), Circuit breaker Auxiliary switch “Normally closed” (‘b’ contact), Phase angle measuring or out of step relay, Automatic selective control or transfer relay, Main-I: Non switched or Numerical Distance Scheme, Main-II: Non switched or Numerical Distance Scheme, Main-I : Non switched distance scheme (Fed from Bus PTs), Main-II: Switched distance scheme (Fed from line CVTs) With a changeover facility from bus PT to line CVT and vice-versa. 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’. Practical experience indicates that numerical relays are as reliable as relays of earlier technologies. A. Thank you , IT IS VERY HELFULL AND HELP TO IMPROOVE ELECTRICAL IND. Within built software with predefined values, Induction disc, electromagnets, induction cup, balance beam, R, L, C, transistors, analogue ICs comparators, Microprocessors, digital ICs, digital dignal processors, Microprocessors, digital ICs, digital signal processors, Electrical qtys converted intomechanical force, torque, Level detects,comparison withreference value in analogue comparator, A/D conversion, numerical algorithm techniques. Generally, there are several different types of numerical protection relays. 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. Over Current/ Earth Fault:When excessive current flows through a system it will trip the circuit br… He is member of Institution of Engineers (MIE), India. The CMC 356 is the universal solution for testing all generations and types of protection relays. 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