Network Protocol, version 3) is a messaging-based communication protocol. Due to these factors, numerical relays are referred to as present generation relays. ways either Latch or Unlatch. Advantages of Numerical relays: Compact Size: Electromechanical Relay makes use of mechanical comparison devices, which cause the main reason for the bulky size of relays. An interface is added to bring the microprocessor-based-relay feature. The argument against putting many features into one piece of hardware centres on the issues of reliability and availability. As part of the process, Get access to premium HV/MV/LV technical articles, electrical engineering guides, research studies and much more! These can then be printed or uploaded to the user’s database facilities. Circuit breaker status is given by BI is either ON/OFF. RELAY: A Relay is a protection device that senses the fault in the circuit and gives a Your email address will not be published. Many functions previously implemented in separate items of hardware can then be included in a single item. Advantages ① It has been widely used in numerical control and automatic control. System operators normally require knowledge of the state of all circuit breakers under their control. configured LED picks up as soon as the indication exists and remains picked up Required fields are marked *. This is often done using a Discrete Fourier Transform (DFT) and the result is magnitude and phase information for the selected quantity. From these samples numerical relays calculates root-mean-square values of … protocol is mainly used in industry and by power supply corporations. There are two types of phase comparators: ), Auxiliary protection functions (broken conductor, negative sequence, etc. Any numerical relay usually consists of the following essential parts. Also the operator can program the relay remotely with a group of settings if required. Get numerical relays at best price with product specifications. 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. Relay is the heart of the protection circuit, as if Electromechanical Relays are the oldest type of relays. Fault levels are significantly different on parts of the network that are energized under normal and emergency generation. Now a day for - Software problems are minimized by rigorous use of software design techniques and the ability to download updated software. button manually or via the system interface (SCADA or DCS). This session gives insights on Numerical relay and its advantages over electro mechanical relays. These protocols helps to communicate relays among In Electromagnetic relays operating current flows through the coil. Similarly, the amount of data that must be recorded is much larger, requiring larger storage. relays is communication between relays and other equipment in the network is I A digital protective relay may also be called a "numeric protective relay". 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. It is also called numerical relay. 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. It must work at high speed, use low voltages, yet be immune to conducted and radiated interference from the electrically noisy substation environment. CT supervision is carried out more easily. until the relay is reset at the device. However, it is sufficiently accurate for an operator to assess system conditions and make appropriate decisions. 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. The numeric relays are mostly used in the generating stations and substations for automated protection. The software provided is commonly organised into a series of tasks operating in real time. (1 relay can be used as over current only for under voltage we use another relay). The extra facilities in numerical relays may avoid the need for other measurement and control devices to be fitted in a substation. but numerical relay is having LCD to indicate the alarm and relay activation. Advantages Due to the use of Indication on LCD for relay activation the numerical Relay is in Compact Size. Numerical relays perform many more functions than earlier generations of relays so testing them is more complex. Practical experience indicates that numerical relays are as reliable as relays of earlier technologies. Numerical relays are classified broadly into four different types as Overcurrent relays, Distance relays, Directional relays and Differential relays ... advantages over the other relays such as reduced size, reduced number of protection elements, reduced cost, increased speed etc. One obvious development is the provision of RTU facilities in designated relays that act as local concentrators of information within the overall network automation scheme. 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. ADVANTAGES OF NUMERICAL RELAYS 1) Compact Size: Numerical relay is compact in size, and uses LCD to indicate relay activation. The memory can easily be expanded to allow storage of a greater time period of input data, both analogue and digital, plus the state of the relay outputs. Advantages of Numerical Relays: Numerical relay consists of many functions in one relay thus replace many traditional relays with one. They are simple in construction. Advantages of numerical relays. The distinction between digital and numerical relays is particular to Protection. Figure 1, Figure 2 and Figure 3 show typical numerical relays, while Figure 4 and Figure 5 show typical numerical relay boards. RE: differences between static, digital, and numerical relays DiscoP (Electrical) 23 Mar 09 17:05. And the simulation results show the advantages of the proposed method in reducing the time needed by the relay to clear the electrical fault. Due to the use of optocouplers, the power required for control signals is extremely low (about ten milliwatts can work normally), and the required control level is compatible with common integrated circuits such as TTL, HTL, CMOS, etc., and can be directly connected. Listed numerical relays manufacturers, suppliers, dealers & exporters are offering best deals for numerical relays at your nearby location. However, by providing a substantial number of digital I/O and making the logic capable of being programmed using suitable off-line software. One of the major advantages of numerical relays is that it can store pre-fault as well as post-fault dataso that it can be us… Advantages of Numerical relays 1. Many complicated functions can be and mechanical relay required more electrical wiring but numerical relay required very less wiring. IEC61850 with RJ45 interface or Fibre interface: The Ethernet-based IEC 61850 protocol is the worldwide standard for protection and control systems used by power supply corporations. 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. The introduction of numerical relays replaces some of the issues of previous generations of relays with new ones. record including with the graphs. by the relay to breaker in the case of fault. Front side of any Numerical Relays usually have the following components. them and also with HMI through modem. Electromechanical, have been gradually been replaced by Static and then by Numerical Relays. 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. All of the relaying functions are performed on these numeric values. the indication no longer applied. One of the significant advantages of a solid state relay over an electromechanical relay is its response time (ability to turn on and turn off). no manual reset required. setting can be manually changed. 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. This paper discusses methods of analysing waveform recordings from numerical relays to diagnose power system events and confirm relay operations. Ok, let’s start with introduction to numerical relays, then explaining their additional features and at the end to discuss important considerations regarding software, data management, etc.. Table 1 provides a list of typical functions available, while Table 2 summarises the advantages of a modern numerical relay over static relay equivalents. The typical architecture of a numerical relay is shown in Figure 6. This process then requires a rigorous system of software version control to keep track of: With an effective version control system, manufacturers are able to advise users in the event of reported problems if the problem is a known software related problem and what remedial action is required. These relays are useful for protection of 3-phase AC induction motors against various hazards. The protection relay no longer performs a basic protection function but is an integral and major part of a substation automation scheme. of starts/reaccelerations, total running time, The different software versions in existence x the differences between each version. 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. B. Numerical relays are natural developments of digital relays due to advances in technology. 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. This is perhaps the most obvious and simple function to implement, as it involves the least additional processor time. Source(s): Basler Electric's BE1-11f FEEDER PROTECTION … The process used for software generation is no different in principle to that for any other device using real-time software, and includes the difficulties of developing code that is error-free. Numerical relays are natural developments of digital relays due to advances in technology. Numeric relays, on the other hand, are programmable relays where the characteristics and behavior can be programmed. parts hence accurate operation. 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. They are reliable. configured LED picks up as soon as the indication exists and drops as soon as A copy of the setting data (including user-defined logic schemes where used) can also be stored on the computer. An essential component is the Real Time Operating System (RTOS) which ensures that the other tasks are executed when required, in the correct priority. Other software depends on the function of the relay, but can be generalized as follows: The relevant software algorithm is then applied. Some relays have These are the advanced version of relays by using 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. The following are the various types of numerical relays, Your email address will not be published. Numerical relays, on the other hand, operate on digitized secondary signals. The Advantages of Electromechanical relays are-They are quick acting and can be reset fast. Electromechanical and static relays have fixed wiring and the setting is manual. This uncomplicated, serial Binary Outputs are the Commands ), Consistency of operation times – reduced grading margin, Sequence quantities (positive, negative, zero), Max. 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. The distinction between digital and numerical relays is particular to Protection. It is now possible to implement a substation automation scheme using numerical relays as the main hardware provided at bay level. achieved with developed logics using various Gates. Typically 12 to 32 samples per fundamental power system cycle are used depending on the particular relay design. Different configurations may require different relay settings to maintain the desired level of network protection. It consists of one or more digital signal processors, some memory, digital and analogue input/output (I/O), and a power supply. The values that the relay must measure to perform its protection function have already been acquired and processed. Numeric relays are programmable relays. Frequent configuration is not needed. Conducting Materials and Their Applications: Numerical relay consists of many As with earlier generations of relays and according to market segmentation, manufacturers offer different versions, each with a different set of functions. If only one or two phases are lost, the VT failure algorithm can be accomplished. 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. For faster real time processing and more detailed analysis of waveforms, several DSPs can be run in parallel. The characteristics and behavior of the relay are can be programmed. If suitable VTs are used, supervision of the VT/CT supplies can be made available. Substation LAN is integrated with fiber optics to compete with the communication capacity. When the operating current becomes large, the magnetic field produced by electromagnet is high such that this magnetic field pulls the armature or plunger making the trip circuit contacts to close. appearance is good. Each relay element is in software so with modular hardware the main signal processor can run a vast variety of relay elements. The alternative is to provide each input with a dedicated A/D converter and logic to ensure that all converters perform the measurement simultaneously. Additionally, the input signals must be amplitude limited to avoid them exceeding the measurement range, otherwise the waveform is clipped, introducing harmonics. Numerical relays All numerical relays utilize so-called sampling technique of the input current and voltage signals. 2) Flexibility: We can modify its functional operation by changing codes in software. Additionally Numeric relays have Communications capabilities, sequence-of-events recording, fault reporting,rate-of-change frequency, and metering functions, all in an integrated system. Disturbance records and data relating to energy consumption requires time tagging to serve any useful purpose. Numerical relay is also a digital system, which is concisely communicating with substation automation. Application of Relays – Relay Selection Method: Ground Fault Protection-Restricted versus Unrestricted Methods, Short Circuit Current Calculation-MVA Method. These relay can protect various components such as feeder, Motor, Generator, Transmission line, Transformers and Bus bars. This is not possible for electromechanical relays. 1 relay can perform only 1 function. In transmission networks, it may be necessary to provide a single recorder to monitor several circuits simultaneously, and in this case, a separate disturbance recorder is still required. 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. change the entire settings of the relay by simply changing Group setting. When this operating current increases, coil energizes the electromagnet. 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. 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. Modern numerical relays will have comprehensive self monitoring to alert the user to any problems. One relay can be used in many ways. the numerical relay having compact size compared to electro mechanical relays, the electro mechanical relays having lot of components, including flag systems. Modern numerical relay protection scheme offers multi-function and multiple characteristics, and other several advantages. 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. 2. Relay back side usually consist of different Terminal Blocks [TB] for giving the Digital and Analog inputs, outputs . Relay communication is provided These relays are usually microprocessor based and are programmable according to the needs of the user. Once you know about th… Incorrect results are then obtained. 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Components of the user to any problems system interface ( SCADA or DCS ) be recorded is much,. Distribution networks, this trend will continue function but is an IRIG-B or IEEE 1588 signal, which be... Concisely communicating with substation automation scheme lost, the amount of data that must be addressed are follows!