Primary reason for relay failure to operate during faults are wrong settings, bad contacts and open circuit in the relay coil. 1. The effects of electrical faults are as follows: Some examples of fault limiting devices are as follows: In ring main feeder system, single end fed system of parallel feeders directional relays are used. Whenever a fault occurs in a system, the protective relay operates and signals … The information presented here is merely a collection by the committee faculty members for their respective teaching assignments as an additional tool for the teaching-learning process. How the electrical power system protection is divided? Phenomena . Enter your name or username to comment. QUESTION #4 What voltage would you read if you placed your leads from L1, L2, or L3 to ground of a 460-volt AC, three-phase power system, Y-connected? The three-phase induction motors are self-starting and more efficient whereas the single-phase motor is not self-starting and requires an auxiliary means for the start of motor. Answer Explanation ANSWER: Both (a) and (b) Explanation: No explanation is available for this question! Created by the Best Teachers and used by over 51,00,000 students. The load factor i= _____. Which of the following bar schemes is the most expensive? Sorry, you have Javascript Disabled! Step -1 Get your basics clear. C. Ease of fabrication . A list of top frequently asked Power System interview questions and answers are given below. The protection is provided in the system to protect each and every element of the power system. Power System Protection and Switchgear by Badari Ram, D.N Viswakarma, TMH Publications; REFERENCE BOOKS: Switchgear and Protection Notes – SGP Notes – SGP Pdf Notes. Electrical engineering (MCQ) objective questions and answers for interview, freshers, Students, PSU exam, GATE preparation, IES, competitive exams etc. The main … Earthing protects the person from the short circuit current. C. Increases the cost of station equipment. Q.2. For the continuity of the power system, it is necessary that they should maintain perfect synchronism under all steady state conditions. Save my name, email, and website in this browser for the next time I comment. Book Name – A Course In Power Systems By JB Gupta Author – J B Gupta Publisher – Katson Books Language – English Paperback – 550 Pages Power System Interview Questions. To see this page as it is meant to appear, please enable your Javascript! The difference between the relay and the circuit breaker is that relay is a switching device that gives the signal to the circuit breaker in case of fault occurrence, whereas circuit breaker breaks the circuit automatically when receives the signal. When the fault occurs on the bus bar, then the whole of the supply gets interrupted, and all the feeders are disconnected in this case Busbar protection is provided to the system to eliminate the occurrence of these faults. 3. Must book for power system courses. Adjacent zone of protection overlap because if we do not overlap then some portion of the power system will be left out unprotected. Root partition is where the operating system kernel is located. How the electrical power system protection is divided? Electrical grounding or merely grounding is a safety measure used to prevent people accidentally coming in contact with the hazardous electrical faults. The slack bus serves as angular reference for all the buses in the system. Resistance winding limits the fault current and protects the system from transient overvoltages. Tag: multiple choice questions in power system protection Power System Protection and Relays Questions & Answers S Bharadwaj Reddy April 25, 2016 September 11, 2016 Why Power Protection Is Important for Security Systems Security system installers must consider all the factors impacting success of a system to provide a more comprehensive value to clients. 20! interrupts the powers supply and damages the damages the electrical installations. Earthing is important because of the given below reasons: 'Sag' is the difference in level between the points of support and the lowest point on the conductor. Schimmelsanierung [eco] ist immer die richtige Wahl. 6. The difference between electrical earthing and electrical grounding is that in grounding the current carrying part is connected to the ground, whereas in earthing the non-current carrying part is connected to the ground. The protective system must function whenever it is called upon to operate, since the consequences of non-operation can be very severe. When the disturbance occurs in the system, the system develops a force due to which it becomes normal or stable. What do you mean by loss of excitation in the context of generator protection? It also contains other potentially important system files that are mounted during boot time. B. Examples of protection relays – Micom, Ref and Siprotec. That is why automatic switch gears are needed for the protection of generators and lines. Unit 4. Internal faults are the faults that occur inside the zone and external faults are the faults that occur outside the zone of protection. The existing weather conditions like lightning strikes, heavy rains, heavy winds, salt deposition on overhead lines and conductors etc. In electromagnetic attraction relay plunger is drawn to the solenoid or an armature is attracted to the poles of the electromagnet. Power system comes into existence with the growing demand of electrical energy. a) Thermal emission b) Alternators c) Field emission d) Transmission lines Ans: (d) 2. Rejinpaul Nov Dec 2019 Important Questions UG PG Anna … It is an electrical device designed to initiate the isolation of a part of the electrical installation, or to operate an alarm signal, in the event of abnormal condition or a fault. Importance of stability analysis in power system planning and operation - classification of power system stability - angle and voltage stability – Single Machine Infinite Bus (SMIB) system: Development of swing equation - equal area criterion - determination of critical clearing angle and time – solution of swing equation by modified Euler method and Runge-Kutta fourth order method. Power Swing . Comment. Sunil S.Rao, “Switch Gear and Protection”, Khanna Publication . D. None. 19! Important Questions provided here are the Expected questions that are possible to be appeared in the upcoming exams.you can make use of the below questions and prepare for your exams. IDMT (Inverse time relays with definite minimum time). Low-cost Your Comments. 1) What is the Power plant or Power Station? For removing the faults the entire circuits connecting the faulty section needs to be open. Often at really high power levels the battery will take up a full room, and certainly more floor space than the UPS system it supports. D. None of the above View Answer. Duration: 1 week to 2 week. Economic Operation of Power Systems. The generation, distribution, and transmission system together constitute a network called as Power plant. For satisfying this quick disconnection the protection relays should have following functional requirements. Power system protection is a powerful engineering branch that deals with electrical system protection. The overall system protection is divided into. Viele Schimmelsanier-Systeme versprechen, die Ursachen des Schimmelbefalls zu bekämpfen. Bundle conductors are used to reducing the Corona and Skin effect. At higher power levels it is common to find more conventional wet-cell batteries in use. An industrial consumer hall a daily load pattern of 2000 KW, 0.8 lag for 12 Hra and 1000 kW UPF for 1J Hr. Protective Relay Systems . Protections must isolate only the faulted equipment, with no over-tripping of unaffected … Different types of protection for electrical systems and networks. The relay should be sensitive enough to respond to the smallest fault, therefore, the pickup value should be less than the smallest fault current. a) 4 kV b) 25 kV c) 10 kV d) 36 kV Ans: (d) 3. It is fair to say that without discriminative protection it would be impossible to operate a modern power system. Electrical Power System Components . Discrimination by Time 40! The pickup value of the relay should be more than the maximum load and it should allow the normal load as well as the certain degree of overload to be supplied. Standby Power Systems for Industrial and Commercial Applications Gold Book™— IEEE STD 493™-2007, Recommended Practice for the Design of Reliable Industrial and Commercial Power Systems White Book™— IEEE STD 602™-2007, Recommended Practice for Electrical Systems in Health Care Facilities At the most basic level, these devices are inserted into the power distribution system to “break,” isolate, or disconnect the circuit if there is an overload or short-circuit condition. Some topics which are covered in this course are: Distance Relays, RRRV and Recovery Voltage in CB, PSM and TMS etc.Various topics like resistance switching and previous year questions will be added soon. This Security provided to the system is called the 'Zone of protection'. Whenever abnormal conditions occur, the relay close its contacts. Electrical4U’s MCQs are in a wide range of electrical engineering subjects including analog and digital communications, control systems, power electronics, electric circuits, electric machines – and much more. The commonly used schemes for the protection are: Internal faults are the faults that occur within the zone of protection and external faults are the faults that occur outside the zone of protection. In this course, important topics from power system protection are explained. power system is balanced 3-phase a.c. .However, due to sudden external or internal changes in the system, this condition is disrupted. When the insulation of the system fails at one or more points or a conducting object comes into contact with a live point, a short circuit or a fault occurs. Relay time is the interval between the occurrence of the fault and the closure of the relay contacts is called relay time. I created this video with the YouTube Video Editor (http://www.youtube.com/editor) Power distribution system deals with transmission of electric power from generating station to the loads with the use of transmission and distribution substations. We have over 5000 electronics and electrical engineering multiple choice questions (MCQs) and answers – with hints for each question. Power system protection. Primary protection (Main protection) is the essential protection provided for protecting an equivalent/machine or a part of the power system. Achieving Selectivity . Häufig muss man hier jedoch Abstriche in puncto gesundheitliche Unbedenklichkeit, Umweltverträglichkeit und … The objective of using this scheme is to keep power system stable and leaving the network still during operation. Power Factor is lowered due to various factors like use of transformers and other inductive loads, use of arc lamps etc. All rights reserved. Electro-magnetic attraction and electro-magnetic induction. Power system is a very interesting and an important subject of EE. In this article, you will learn the importance of protection in the modern power system and why we need power system protection. 1.Describe the essential features of a protective relay with reference to (i) Selectivity (ii) sensitivity (iii) speed (vi) Reliability and dependability. Special Protection Systems . Trust me good preparation in it will boost up your confidence to a great level. The objective of power system protection is to isolate a faulty section of electrical power system from rest of the live system so that the rest portion can function satisfactorily without any severe damage due to fault current. Answer: Galloping in transmission line conductors arises generally due to symmetrical layers of ice formation. After the relay sensing the fault condition, relay operates and close the trip coils. Circuit breakers are essentially. If any fault occurs in the system then the relays associated with it trip all the circuit breaker so that the faulty element gets removed from the power system. Question3: What do you mean by reach and reach point of the relay? The relays that are usually employed for protection of transmission lines include. a. Electro positive b. Electro negative c. Both (a) and (b) d. None of these. Whereas the backup protection provides the backup to the primary or main protection whenever it fails in operation and cut out for repair. Best Videos, Notes & Tests for your Most Important Exams. Here we have provided EE6702 Protection and Switchgear Important Questions Nov Dec 2019. Primary protection also known as main protection is the first line of protection which provides quick acting and clearing of the fault within the boundary of the elements it protects. Link: Complete Notes. No explanation is available for this question! The relays are connected to the power system through the current transformer (CT) or potential transformer (PT). why we need power system protection. Explain the requirements … Enter your email address to comment. An example of the power system is a grid that supplies power to the other system. Sub Synchronous Resonance . What is the reason of arising Galloping in transmission line conductors? Grounding does not have zero potential but earthing has zero potential. • By dividing the power system into protection zones the extent of disconnections can be limited . Modern power protection systems, whether UPS or SPS, utilize sealed, maintenance free batteries, almost exclusively, to power levels in excess of 5 kW. Over-Current Protection 38! Electrical Power System by JB Gupta is very useful for basics ideas of power system and best for competitive exams And topics are covered in sufficient details. Distance relay operates whenever the impedance seen (V/I) seen by the relay is less than the specified set value. Torque is developed by electromagnetic induction principle. We can use the fuses only once but circuit breakers can be used many more times, and the breaking capacity of the fuse is low as compared with the circuit breaker. Low-cost . 2) SF 6 is which type of gas? Anna University Regulation 2013 EEE EE6501 PSA 2marks 16marks for all 5 units and EE6501 PSA Short answers, Question Bank for Power System Analysis are listed down for students to make perfect utilization and score maximum marks with our study materials.. Reach is the limiting distance covered by the relay for protection of line. EE6501 PSA 2marks. An electric power system is a network of electrical components deployed to supply, transfer, and use electric power. Answer on first question: Functions of a protective relay: The protective relaying senses the abnormal conditions as a part of the power system and gives an alarm or isolate that part from the healthy system. 18! In the three-phase system, the power delivered is constant whereas the power delivered in the single-phase system is pulsating in nature. Download the Important Questions using the below link. Ravindranath, M.Chander, “Power System Protection and SwitchGear”, Wiley Eastern Ltd. New Delhi [3]. Overcurrent protective devices (OCPDs) include relays, circuit breakers, or fuses and are one of the basic building blocks of power distribution systems and their protection. This causes huge amount of current to be drawn as the reactive power increases and the power … © Copyright 2011-2018 www.javatpoint.com. What are the fundamental elements of relay? Download the Important Questions using the below link. The relays are connected to the power system through the current transformer (CT) or potential transformer (PT). (a) 0.5 (b) 0.75 (c) 0.6 (d) 2.0 Ans: c In case of electro-magnetic induction, principle of operation is similar to induction motor. Actually circuit breaker isolates the faulty system from rest of the healthy system and these circuit breakers automatically open during fault condition due to its trip signal which comes from protection relay. The overall system protection is divided into. Developed by JavaTpoint. In the electrical installation, the primary protection is provided to each section. Important Questions provided here are the Expected questions that are possible to be appeared in the upcoming exams.you can make use of the below questions and prepare for your exams. This is module three part 3 of our Fundamentals of Modern Protective Relaying introducing Power Systems Protection. The output of the three-phase machine is higher than a single-phase machine for a given size of a frame. Anna University Regulation 2013 EEE EE6501 PSA Important Questions with Answer Key for all 5 units and EEE 5th SEM EE6501 Power System Analysis Answer Key is listed down for students to make perfect utilization and score maximum marks with our study materials. Trust me good preparation in it will boost up your confidence to a great level. Power System Protection & Control IEEE PES Distinguished Lecturer Program Preceding IEEE PES Vice President for Chapters melihas@ieee.org PES Student Energy Conference (ZEC 2015), Zagreb, Dec 10th, 2015 1. 41! 3) A fuse wire of circular cross section has a radius of 0.8mm. Transformers and other inductive loads draw current which lags the induced voltage. 39! Q:What is reverse power relay? There are two types of faults that occur in a three-phase system. The causes of electrical faults are as follows: The tendency of an alternating electric current (A.C) to get distributed within a conductor such that the current density becomes largest near the surface of the conductor, and decreases with greater depth in the conductor, is called as "Skin Effect.". Link: Unit4 Notes. Transformers and other inductive loads draw current which lags the induced voltage. The main work of transmission line and distribution line is to transfer power from one place to another but the difference between transmission and distribution line is based on the factors like the type of phase, the distribution line because the wire for transmission line is thick and for distribution line is thin, the transmission line requires three phase supply for carrying electricity and distribution line requires single phase supply for carrying electricity. Das Remmers Power Protect System ist mit dem eco-Label und dem Blauen Engel ausgezeichnet und trägt deshalb den Zusatz [eco]. 37! We have the largest collection of Instrumentation Engineering Multiple Choice Questions (MCQ) to prepare for the Competitive examination. Generator Protection Interview Questions & Answers, Electrical Cables Interview Questions & Answers, Methods to Reduce Step Potential and Touch Potential in Substation, What is the function of a relay in power systems, question bank for protective relays exam with solved problems, power system protection question and answers pdf, protective relay and circuit breaker interview question, POWER SYSTEM PROTECTION QUESTION AND ANSWER PDF, what is torque control in protective relay. Most of the power distribution or utility companies rely on manual labor to perform the distribution tasks like interrupting the power to loads, all the parameter hourly checking, fault diagnosis, etc. Busbar Protection | Busbar Protection Objective Type Questions and answers. If the Y-connected system is solidly grounded, you will read 266V from line to ground. Enter your website URL (optional) Find a content. Q.1. Unit 2. In resistance grounding, one or more resistance is connected to the neutral of the system. Time grading • Example from Strauss 4.4.2. Electrical faults are also caused because of human errors such as selecting an improper rating of equipment, switching the circuit while it is under servicing etc. JavaTpoint offers college campus training on Core Java, Advance Java, .Net, Android, Hadoop, PHP, Web Technology and Python. Step -1 Get your basics clear. The effect of this will be circuit breaker operate to open the contacts. Electrical4U’s MCQs are in a wide range of electrical engineering subjects including analog and digital communications, control systems, power electronics, electric circuits, electric machines – and much more. Power system protection Question Bank , by questionbank2u Review questions. Power system is a very interesting and an important subject of EE. Test Set - 2 - Switchgear and Protection - The test carries questions on topics such as Arc Extension in Circuit Breakers, Restriking voltage in Circuit Breakers, Restriking Voltage in Circuit Breakers, Air Blast Circuit Breaker, Sulphur Hexafluoride Circuit Breakers, Vacuum Circuit Breakers, Oil Circuit Breaker and Protective Relays etc. 35! B. Fundamentals of Power System Protection by Paithankar and S.R.Bhide.,PHI, 2003; Art & Science of Protective Relaying – by C R Mason, Wiley Eastern Ltd. What are different types of principles of operation of electro-mechaical relays? The overall system protection is divided into. 1.0.2 CAUSES OF POWER SYSTEM FAULTS Three phase motors have higher power factor whereas the single phase motors have low power factor. The advantages of the three-phase transformer over a single-phase transformer are as follows: The minimum phase to a neutral voltage that is required for corona discharge to start is called the Critical disruptive voltage. What are the different relays that employed for protection of apparatus and transmission lines? Increases losses in line. On the basis of a characteristic, protection relays can be categorized as follows: The value of current or voltage below which the relay opens it contact is called the reset level of the relay. This is accomplished by duplicate A and B protections and duplicate power supplies. Surge Harmonics Frequency Variations . This impedance or corresponding distance is known as reach of the relay. Over current relay meant for sensing any internal short circuit, over load condition ,earth fault thereby reducing the system failure & risk of fire.So, for a better protection of the system.It should have both over voltage & over current relay. Answer: The transmission line is not fully stretched but it is allowed to sag down. The relays are connected to the power system through the current transformer (CT) or potential transformer (PT). Over voltage relay meant for sensing over voltages & protect the system from insulation break down and firing. For the proper functioning of the electrical system back up protection is essential. An example of the power system is … How relays are connected in the power system? Mail us on hr@javatpoint.com, to get more information about given services. The faults that occur in the three-phase power system are as follows: The reach point is the farthest point from the relay which is still inside the zone of protection and reach is the distance between the reach point and relay. DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING EE6501 PSA Important Questions. Backup Protection Zones . Here we have provided EE6702 Protection and Switchgear Important Questions Nov Dec 2019. 22! Link: Unit 1 Notes. Directional Relays 42! Unit 5. 3. 43! power system protection, Consistent protection across all protection levels, thanks to coordinated protective devices; Space-saving and inexpensive installation, thanks to slim design; Know what's happening in advance, thanks to the predictive testing of the pluggable protective devices; Surge protection for power supplies is part of the COMPLETE line system Bulk oil circuit breaker is suitable for voltages upto. 250+ Electrical Power System Interview Questions and Answers, Question1: What do you mean by zone of protection? Faults beyond the distance (reach of the relay) relay will not operate and should be covered by the other relay. Question2: What are internal and external faults? Link:3 Notes. In simple words relay is an electrical device that gives signal to isolation device (eg: Circuit Breaker) after sensing the fault and helps to isolate the fault system from the healthy electrical system. A list of top frequently asked Power System interview questions and answers are given below. II. QUESTION BANK with SOLVED 2 MARK Qs POWER SYSTEM ANALYSIS UNIT 1: INTRODUCTION. Equipment . D. Both b and c. Ans: D. Q.9 Improving power factor-A. When the fault occurs relay operates and close the trip coils and circuit breaker operates and open the contacts subsequently and fault is cleared. See instructions. Overlapping protection zones 36! Please mail your requirement at hr@javatpoint.com. Power Factor is lowered due to various factors like use of transformers and other inductive loads, use of arc lamps etc. In this project you will consider the important problem of minimizing the cost of producing a given amount of electrical power from a group of non-identical generators. The power plant uses the form of energy such as coal, diesel and converts it into electrical energy. Generator protection; Transformer protection; Busbar protection; Transmission line protection and; Feeder protection; How relays are connected in the power system? Some previous year questions are taken and topics related those are explained. Your name: Your Email: Your Comments: 7. EduRev, the Education Revolution! This ring of security is called ‘Zone of protection’. Reduces current for a given output. Basic fundamental elements of the relay are: What are the good features of protective relaying? Sub. Question5: How do you select the pickup value of a relay? 'Corona' is the phenomenon of violet glow, hissing noise, and production of ozone gas in an overhead transmission line. Transmission subsystem. This is a problem faced by utility companies every day, as changes in consumer demand force them to generate more or less power. Malfunctioning, aging, insulation failure of cables and winding leads to failure of equipment like generators, motor, transformer. Search for: Related. Action carried out by the relay and circuit breaker during fault condition? Due to which of the following reasons aluminium is being favoured as bus-bar material? A bundle conductor consists of two or more parallel subconductors at a spacing of several diameters. The arcing ground risk is decreased by the resistance grounding and permits the ground fault protection, whereas resistance earthing system is provided in electric equipment to protect the equipment from the occurrence of the fault in the system. 1.In a circuit breaker, are is initiated by the process of. The power plant uses the form of energy such as coal, diesel and converts it into electrical energy. Unit 3. If there is any fault associated within the ring the relays associated with it must trip all the allied circuit breakers so as to remove any faulty element from rest of the power system.

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