Operation and maintenance of protective relays and. Differential protection i 1p i 1s ct1 20005 a i 2p i 2s bus ct2 20005 a h1 x y i i 1s i 2s i i 1s i 2s i i1p i2p i 2s i 1s. However you will need different types of interfaces at the rtus. Most early microprocessor relays became obsolete so fast thanks to moores law that again there was concern in the industry of a repeat of the static relay scenario and a continued resurrection of electromechanical relays was a. Advantages of static relays static relays in general possess the following advantages.
Actually, a relay is nothing but a combination of one or more open or closed. Most protection relays are also designed to sense one fault category, only necessitating the installation of several units to cover all potential faults. Basic relay concepts electromechanical static digital. Voltage restraint over current relay b based on logic. Three zone protection by using distance relays in simulink.
General equation of phase and magnitude comparators, duality of comparators. Utility grade relays have much higher reliability and accuracy than industrial grade relays see tables g24 and g25. One of the protection relays used in power system is distance or impedance relay which is mainly used in transmission system these relays can be used as primary or backup protection. This ratio is proportional to the distance along the line, and the relay that measures the distance is called. Distance protection relay distance protection relay is the name given to the protection, whose action depends on the distance of the feeding point to the fault. So, if a fault happens on any line, it will be cleared by its relay and circuit breaker. Protective relaying philosophy and design guidelines. Implementation of outofstep relays to protect generators 3. This type of relay is connected in a circuit and this type of relay operate when the current of the circuit increase beyond the normal. One of the more common forms is the differential current relay. A ups, or a uninterruptible power supply, is a device used to ba ckup a power supply to prevent devices and systems from power supply problems, such as a power failure or lightning strikes.
I type icwsib relaydisassembled front view 2 outer block case. As example, distance relays are suitable for transmission lines, and differential relays for power transformers and bus bars. Although there are different types of over current relays but basic working principle of over current relay is more or less same for all. Primary and secondary or backup protection in a power. Power directional relays type icw connecting plug inner block fig. In this type of relay, an iron core or plunger is moved into the solenoid coil. Three zone protection by using distance relays in simulinkmatlab. Different types of relays used in protection system and. Protective relays home national switchgear carries hundreds of new, used and reconditioned protection relays, everything from the traditional electromechanical and the modern solid state or microprocessor based versions of overcurrent, under voltage, ground fault, transformer and bus differential, motor protection and many more. These classifications include electromagnetic, solid state, high voltage, thermal relays, and so on. Figure 1 above shows examples of simple and complex static relays and figure 2 shows the circuit board for a simple static relay. The first power relays of induction type was introduced 1924, type re voltage regulation relays an induction relay for voltage regulation of. Actually, a relay is nothing but a combination of one or more open or closed contacts. It also covers power system, transformer protection and zone of protection.
Relays are classified into several types based on their functionality and application they are implemented for. Operation and maintenance of protective relays and associated. Authors paul price bureau of reclamation hydroelectric research and technical services group denver, colorado 5f. Authors paul price, nate myers, jim dehaan bureau of reclamation hydropower technical services group denver, colorado 5d. Operation, maintenance, and field test procedures for. Distance relays are designed to respond change in current, voltage, and the phase angle between. This impedance between the relay and the fault depends on the electrical distance between them. Based on operation mechanism protection relay can be categorized as electromagnetic relay, static relay and mechanical relay.
At any relay location, three impedance relays and a directional unit connected in series with the impedance relays are provided. Lecture notes on veer surendra sai university of technology. Relay classification, principle of different types of electromagnetic relay. Distance protection relay is the name given to the protection, whose action depends on the distance of the feeding point to the fault. Types of electrical protection relays or protective relays. Flexible ac transmission system facts have been evolving to a mature technology with high power rating. Faults instrument transformers correlation to drawings other. Different types of relays used in protection system and their.
Currentbalance relay, directional type, 62 for line protection, 330 overcurrent type, 58 current biasing, for mho relay, 82 for offset impedance relay, 77 to avoid distance relay misoperation on arcs, 346 current compensation for ground distance relays, 360 current switching for distance relays, 368 current transformers, accuracy calcula, 1. Benders ground fault relays safeguard equipment, personnel, and processes while reducing your costs and system downtime. Backup relay x y load l2 load l1 t1 s bus over current backup relay differential relay. In electrical engineering, a protective relay is a relay device designed to trip a circuit breaker when a fault is detected 4 the first protective relays were electromagnetic devices, relying on coils operating on moving parts to provide detection of abnormal operating conditions such as overcurrent, overvoltage, reverse power flow, overfrequency, and underfrequency. Explain what a gfci is, and then in a larger context. As shown in below fig, each line associated with over current relay that protect the lines from faults. The safety rules applicable the nature of different types of electrical faults and the effect these faults can have on company assets understanding of electrical fault protection systems. Depending on the operating principle and structural features relays are of different types such as electromagnetic relays, thermal relays, power varied relays, multidimensional relays, and so on, with varied ratings, sizes and applications. Technical explanation for uninterruptible power supplies. In utility and industrial electric power transmission and distribution systems, a digital protective relay is a computerbased system with softwarebased protection algorithms for the detection of electrical faults.
In the paper observed estimation of reliability of relay protection rp. Technical explanation for uninterruptible power supplies upss introduction what is a uninterruptible power supply ups. Only utility grade relays can be used for interconnection protection. The first balance relays type rbd for ac was designed 1925, and was used as differential protection for transformers and generators power relays in 1917 also the first power regulation system was introduced. Types of over current relay depending upon time of operation, there are various types of over current relays, such as, 1. In the years since, we have grown and developed a complete line of products and services for the protection, monitoring, control, automation, and metering of electric power systems. Most early microprocessor relays became obsolete so fast thanks to moores law that again there was concern in the industry of a repeat of the static relay scenario and a continued resurrection of. This in turn will prepare the participant for succeeding modules which deal with protective schemes often using a combination of these relays. Protective relaying philosophy and design guidelines pjm. In most of the newer schemes the relays are normally duplicated.
Switchgear and protective devices 2015 5 p a g e modulei lesson plan 1. 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. Operation, maintenance, and field test procedures for protective relays and associated circuits iii acronyms and abbreviations a ampere ac alternating current amp ampere ansi american national standards institute bes bulk electric system carma capital asset and resource management application ccvt coupling capacitor voltage transformers co. Based on operation mechanism protection relay can be categorized as electromagnetic relay, static relay and mechanical. Primary and secondary or backup protection in a power system. Every equipment wants different types of protection relays. Such relays are also termed as microprocessor type protective relays. Protective relays feature past, present, and future a. Faults instrument transformers correlation to drawings. Low burden on current and voltage transformers, since the operating power is. In some existing protection relay schemes, fault detecting and auxiliary relays are not duplicated. The user can also set certain limits for the relay so that it is super sensitive and very precise. Faults relays instrument transformers correlation to drawings one lines ac schematics dc schematics other types of protection coordination of relays protect personnel.
They are functional replacements for electromechanical protective relays and may include many. Primary protection below is the power system protection scheme which is designed to protect the power system parts and components. It is shown, that an existing method, both russian, and foreign, do not allow to evaluate rp reliability correctly. Protective relay circuits worksheet digital circuits. Before undergo protection relays, will see the list different types of protection. Types of protection relays are mainly based on their characteristic, logic, on actuating parameter and operation mechanism. Sel introduced the worlds first digital relay in 1984, revolutionizing the power protection industry by offering fault locating and other features for a fraction of the cost of earlier systems. Protective relays familiarity with the application, basic connections and internal schematics ability to test several relays types. The objectives of this module is to demonstrate the operation of the most common types of protective relay. Bus under voltage protection armature shown in the nonenergized trip position. If any fault occurs at f 1, the impedance of zonei reduce to a lower value than the preset value z 1. All the relays react to voltage or current with the end goal that they open or close the contacts or circuits.
Types of electromagnets relays are classified into the following types, depending on whether or not they have a permanent magnet. This means that generally the operating coils do not have polarity. Power directional relays types icw51a icw52a icw51b icw53a power systems management department general. Nonpolarized relays nonpolarized relays do not use a permanent magnet in their. Bus protection l overcurrent l differential l backup l under voltage. The time of operation of such protection is a function of the ratio of voltage and current, i. Since some relays are frequencysensitive, each of the relay s operating characteristics vs. There are very different functions of protection relays, every one of those relays are ready to touch upon sure type of faults. Selectivity speed reliability stability sensitivity numerical relays are essentially small computers the intelligent electronic device.
Why protection is needed faults and damage to people and equipment principles and elements of the protection system main goals protection zones, primary and backup protection basic protection schemes overcurrent protection and coordination in radial systems directional overcurrent protection distance relay principles, operation, and connections line. The following groupings will be used in this technical guide. Protection systems are created using ctvts, relays and circuit breakers key characteristics are. The settings in a protective relay are usually much more sensitive than what is found in circuit breakers or fuses. Nonpolarized relays nonpolarized relays do not use a permanent magnet in their electromagnetic section. Jun 08, 2019 power system protection relays can be categorized into different types of relays. The idp210 is a full featured relay suitable for a variety of protection applications including feeder protection, reclosing, synchcheck, frequency based load shedding, reverse power, overcurrent, overunder voltage and frequency. Ground fault detection, location, and protection products a comprehensive line of ground fault protection products, utilizing the latest in technology, and covering a multitude of applications and systems. A digital protective relay may also be called a numeric protective relay. Revised edition released november 1998 previously presented at the 12th annual cepsi exhibition, november 1998, international conference modern trends in the protection schemes of. Technical explanation for uninterruptible power supplies upss. A very common example of a differential current relay so common, in fact, that nearly every house is equipped with at least one is the gfci, or ground fault current interrupter. Electrical apparatus idp210 feeder protection relay 165210. Types of relays there are different ways to classify relays.
Types of protection relays are mainly a based on characteristic. Different types of relays, their construction, operation. There are several types of mechanisms used in the different protection relay types, including induction disc, moving coil, and armature mechanisms, each suitable for specific conditions. It also covers power system, transformer protection and zone of. Therefore, this document is intended to describe about a few basic types of relays that are popularly used in typical loadcontrol. According to the relays operating characteristics, the relay may be classified as follows. Types of protective relays and its function my tech info. When a larger number of relays are to be installed, for example by a panel. This technology has wide spread application, became a top rate, most reliable one, based on power electronics. Question 3 a differential relay is a common type of protective relay used in power systems. Relaytorelay digital logic communication for line protection, monitoring, and control kenneth c. The operation of the conventional over current relays either direction or non directional, depend on the magnitude of current or power in the protected circuit, where as the distance protection relay operate on the principle of the ratio of applied voltage to current in that circuit.