Minimum oil circuit breaker Q: What are the main types of stator winding faults? Network Administrator Interview Questions. Why Is Voltage Stepped Up Before Transmission? Hence the relay is called REF relay. Unit test Q. Sudden loss of all or major part of the load causes over-speeding in alternators. So, pickup value should be less than the smallest fault current. Magnetizing inrush current appears wherever a transformer is energized on its primary side producing harmonics. A bundle conductor consists of two more parallel subconductors at a spacing of several diameters.this is use to reduce the corona and skin effect. Power flow through line and slack bus power. Q: What are the limitations of Buchholz relay? The, the flux reaches a peak value in half a cycle. Q: What is the main problem of the circuit breaker? Q:Mention the various tests carried out in a circuit breaker at HV labs. • There is a reduced risk of fire Also it is extremely difficult to find two identical CT’s. Q: What is the backup protection available for an alternator? Faults occurring elsewhere in the system have no influence on the operation of a unit system. Naturally when a fault occurs it is sensed by both the primary and backup protection. Question 5. Definite time relay and inverse-definite time relay. Control Systems-Electrical Engineering Interview Questions. Double end fed power system 2. Single end fed system of parallel feeders. -has 3 vectors equal in magnitude and displaced from each other by an angle 120 degrees and having the phase sequence as original vectors. So if any short circuits occur in the system first high currents bypassed in the Earthling terminal. The resistance reduces the restriking voltage frequency and it diverts part of the arc current. Thermal power station, Hydel power station, Nuclear power station etc. Electrical Interview Questions & Answers visit www.eeekenya.com Page | 1 ... Power factor should be high in order to get smooth operation of the system. If a fault occurring in a zone can be immediately detected and or isolated by a protection scheme dedicated to that particular zone. Q: What are the causes of bus zone faults? Fuse is a low current interrupting device. Q: State the significance of double line fault. Q: What are the causes of over speed and how alternators are protected from it? Faults that occur within the zone are termed as Internal Faults and that occur outside the zone of protection are termed as external faults (can also be called as through faults). Failure of support insulator resulting in earth fault Question 16. Explain The Operating Principle Of Dtoc And Idmt Relays? Arc is a phenomenon occurring when the two contacts of a circuit breaker Q: What are the advantages of MOCB over a bulk oil circuit breaker? Q: Why neutral resistor is added between neutral and earth of an alternator? It has a time adjustment setting and pickup setting. Even CT’s of proper turn-ratio are used, the differential current may flow through the relay under normal condition. Q: State the disadvantages of field tests. quantities to electrical in conjunction with transducers. It may form an explosive mixture Top 18 Electrical Power System Interview Questions and Answers for 27.Nov.2020 to crack your Electrical Power System interview. It consists of overvoltage withstand test of power frequency lightning and impulse voltages.Testa are done for both internal and external insulation with switch in both open and closed conditions. Routine test Q: What are faults associated with an alternator? Q: Mention the advantages of field tests. This current is known as inrush current. Jobs Static relay is compact Contact resistance meter test instruments used to measure low resistance like relays, contactors. Voltage is stepped up before transmission due to … It is the rate of rise of restriking voltage, expressed in volts per microsecond. Q: State the different types of circuit breakers. 2. In addition to this, there always an inherent phase difference between the primary and the secondary quantities and a possibility of current through the relay even when there is no fault. • It absorbs the arc energy to decompose the oil into gases, which have excellent cooling properties It is the minimum current in the relay coil at which the relay starts to operate. It is represented by curves originating in load regions and traveling towards relay characteristics. The risk of fire is diminished By coordinating relays, faults can always be isolated quickly without serious disturbance to the rest of the system. The biased beam relay is designed to respond to the differential current in terms of its fractional relation to the current flowing through the protected zone. The over voltage of the power system leads to insulation breakdown of the Q: Define composite testing of a circuit breaker. Resistance earthing system is done in an electric equipment in order to protect the equipment in occurrence of fault in the system. in this bus the magnitude of voltage and phase angle are specified. Hence the field circuit breaker is opened and stored energy in the field winding is discharged through another resistor. Q:What is over fluxing protection in transformer? Q: Mention any two disadvantage of carrier current scheme for transmission line only. Electro-magnetic attraction and electro-magnetic induction. Question 8. power systems relay questions; power system protection question and answers pdf; protective relay and circuit breaker interview question; protective relay isolation; POWER SYSTEM PROTECTION QUESTION AND ANSWER PDF; what is torque control in protective relay; Share on. The circuit breaker can be tested at only a given rated voltage and network capacity. To see this page as it is meant to appear, please enable your Javascript! Vacuum circuit breaker. Hence the zone of protection in the winding of the transformer is restricted to cover only around 85%. Fault between phase and ground; fault between phases and inter-turn fault involving turns of the same phase winding. With close observation, you will note … Percentage ratio error = [(Nominal ratio – Actual ratio)/Actual ratio] x 100 Your email address will not be published. Q:What are the demerits of using oil as an arc quenching medium? Question 11. A. Buchholz relay is a device which is used for the protection of transformer from its internal faults, it is a gas based relay. Question 6. A. Q: What are the advantages of oil as arc quenching medium? Q: What are the features of directional relay? this effect is only in the ac. Each year, ENR ranks the top 500 design firms in the United States based on annual revenues. Q.1. Power System Protection (17) Electrical Circuits Objective Type Questions (12) Electrical Engineering MCQ'S Objective Type (12) Electrical Engineering Interview Questions (10) Potective Relays Interview Questions (10) electrical power (10) Electronics MCQ's Circuits (9) electrical power engineering (9) Q: Mention any two applications of differential relay. (c) The relay is of slow operating type, which is unsatisfactory. Radial-blast. What are different types of principles of operation of electro-mechaical relays? I interviewed at Electric Power Systems in November 2015. Substitution testing Banking of power 5. This year, POWER was named the number 3 firm in the power … in series. Type test Though IDMT relays offer significant improvement in fault clearing times over DTOC relays, DTOC relays have their own advantage. It assists the circuit breaker in interrupting the magnetizing current and capacity current. Fast operation, auto re-closing possible, easy discrimination of simultaneous faults . Faults in the 3 P system can be classified under the following :-. Explain the difference between POWER BI vs TABLEAU? Using a short circuit generator as the source. It is the transient voltage appearing across the breaker contacts at the instant of arc being extinguished. Q: What are the types of graded used in line of radial relay feeder? 4. Generator Protection Interview Questions Answers. The hiring manager set up an phone interview, then a followup Skype interview with a manager and another relay tech. They has 3 vectors having equal magnitudes and displaced from each other by an angle zero degrees. Q:What are the various faults to which a turbo alternator is likely to be subjected? Earthquake, mechanical damage etc. Air break circuit breaker It has no zero sequence component and the positive and negative sequence networks are connected in parallel. It is the indicator used for showing the operation of the relay. Interview question for Management Trainee in Greater Noida.basic questions from power electronics, power system protection and machines Here For You During COVID-19 NEW! (b) is lighter than air. Required fields are marked *. A. Q: Give the two methods of arc interruption? The Feedback in Control System in one in which the output is … • Opening of single capacitor bank The farthest point from the relay which is still inside the zone of protection is called reach point and the distance between relay and reach point is called reach. In this post provide you latest and updated 2018 Electrical MCQ Objective Questions with answer which are help for preparation all electrical engineering exams like GATE, IES, JTO, PSUs, RRB JE/AEN, RRB loco pilot and technicians, SSC JE, DMRC, LMRC, ISRO and other state level engineering exams. separate under heavy load or fault or short circuit condition. Mention the inductance value of the peterson’s coil. Q: Give the limitations of Merz Price protection. Question 4. • Maintenance is required for the compression plant which supplies the air blast. differential relay. There is a risk of fire since it is inflammable. Now the operating time of backup relay B will be 0.1+0.5+0.4= 1 sec. The internal faults include phase faults, ground faults, inter-turn faults, tap-changer failure, and leakage oil from tank. Q: Differentiate between a fuse and a circuit breaker. What is fault clearance time? A. Q: Give the consequences of short circuit. The necessity to interrupt the normal services and to test only at light load conditions. What Is Different Between Resistance Grounding System And Resistance Earthing System? A single relay can perform several functions like over current, under voltage, single phasing protection by incorporating respective functional blocks. Solid earthing, resistance earthing , reactance earthing , voltage transformer earthing and zig-zag transformer earthing. Grid connections 7. 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. When Are The Directional Relays Used? Top Most Power System Protection Interview Questions Q:What are the functions of protective relays To detect the fault and initiate the operation of the circuit breaker to isolate the defective element from the rest of the system, thereby protecting the system from damages consequent to the fault. Therefore, breaker should be able to carry high current safely for some for some specified period during running i.e. At atmospheric pressure, its dielectric strength is 2.5 times that of air. Q: State the various types of unsymmetrical faults. Q: What are the various faults that would affect an alternator? When the AC passed through the conductor the density of the current is not uniform over the cross-section of the conductor, the density of the current is very high near the surface of the conductor and very low at middle this effect is called skin effect. At the same time, the relay should be sensitive enough to respond to the smallest fault. The generation, distribution, and transmission system … Q: Write the classification of circuit breakers based on the medium used for arc extinction? The power frequency rms voltage appearing across the breaker contacts after the arc is extinguished and transient oscillations die out is called recovery voltage. 2, Incipient or slow developing faults. It refers to the current or voltage which is used to activate the relay into operation. Directional relays are used mainly in single end fed system of parallel feeders, ring main feeder system etc. So the pickup value of the relay should be more than maximum load. The interview seemed pretty superficial and none of the questions were very hard. Q: Mention the withstanding current in our human body. 5. Arial-blast type How Do You Select The Pickup Value Of A Relay? (d) has pungent small. Bucholz relay is used to give an alarm in case of incipient( slow-developing) faults in the transformer and to connect the transformer from the supply in the event of severe internal faults. equipments. Answer : The protection is organized to provide a ring of security around each and every element of a power system. • The air has relatively inferior arc quenching properties Question 1. Top 100 Switchgear and Protection Interview Questions. Q: What are the merits of carrier current protection? What Is The Bundle Conductor And Why Is Used ? It is defined as the time period extending from the occurrence of the fault through the relay detecting the fault to the operation of the relay. A Definite time over current relay (DTOC) can be adjusted to trip out at a definite amount of time, after it picks up. Positive sequence components, negative sequence components and zero Special occasions like breaking of charging currents of long lines ,very short line faults ,interruption of small inductive currents etc… can be tested by direct testing only. This ring of security is called ‘Zone of protection’. This arc delays the current interruption process and also generates enormous heat which may cause damage to the system or to the breaker itself. It is a copper or an aluminium wire. Ring main feeder system. If an earth-fault occurs near the neutral point, the voltage may be insufficient to operate the relay. Electrical Engineering Interview Questions. Differential protection is based on the fact that any fault within an electrical equipment would cause the current entering it, to be different, from that leaving it. Synthetic test Protection of generator and generator-transformer unit: protection of  large motors and bus bars. Answer: The transmission line is not fully stretched but it is allowed to sag down. Effect of vibration is nil, hence can be used in earthquake-prone areas When Will You Go For Idmt And Dtoc Relays? Wheeling of electric power 4. All the sequence currents are equal and the fault current magnitude is three times its sequence currents. When interrupting low inductive currents such as magnetizing currents of the Compensation testing Q: What are the advantages of synthetic testing methods? Can we measure over voltage and over current by measuring current only? Electrical Engineering Objective Questions MCQ with Answer Free Pdf Download. Please click on the Red Plus Icon to know the answer. What are the different types of faults in a transformer? A. Knee point voltage is the voltage at which a CT gets saturated. • It acts as an insulator and permits smaller clearance between line conductors and earthed components. Fuses are burned at the time of over current flows in the circuit but breakers are just open (not burn) at the time of over current flow. Latest 50 Power Analysis Interview Questions, List Of Microprocessor Interview Questions For Freshers & Experienced, Top Most Power systems Objective Questions Part – 5, Top Most Power System Transmission Interview Questions, Power Systems Objective Questions and Answers – Part 1, Power Systems Objective Questions and Answers – Part 2, Power Systems Objective Questions and Answers – Part 3, Power Systems Objective Questions and Answers – Part 4. What is different between resistance grounding system and resistance earthing system? • The air blast circuit breakers are very sensitive to variations in the rate of rise of restriking voltage Q:What are the advantages of static relay over electromagnetic relay? Low power factor means losses will be more.it is the ratio of true power to apparent power. It has good dielectric strength and excellent arc quenching property. It is restricted earth fault relay. If the adjacent zones do not overlap there will be some portion of the power system which is left out unprotected. Q:What are the main safety devices available with transformer? Using the power utility system or network as the source. Q. What is the difference between surge arrestor and lightning arrestor? Question 15. No gravity effect on operation of static relays. Power System Protection and Relays Questions & Answers . (c) A fault in the bus bar causes interruption of supply to a large portion of the system network. Answer: When the fault occurs relay operates and close the trip coils and circuit breaker operates and open the contacts subsequently and fault is cleared. Static relay can think , programmable operation is possible with static relay Q. what is Buchholz relay and the significance of it in to the transformer? Why Does The Adjacent Zones Of Protection Overlap? The operation of a relay should be fast and selective, ie, it should isolate the fault in the shortest possible time causing minimum disturbance to the system. We will go on adding questions, till we reach 100 and may be we will add more than 100. Home » Power System Protection and Relays Questions & Answers. It serves as the first line of defence. 2, Fault between turns Q: How does the over voltage surge affect the power system? Therefore, the IDMT relay will not be of much help. Can convert even non-electrical Over Current protection is not considered necessary for modern alternators because these are capable of withstanding a complete short circuit at their terminals for sufficient time without much over heating and damage. Home » Interview Questions » 300+ [UPDATED] Electrical Power System Interview Questions. SF6 has high affinity for electrons. the defective element from the rest of the system, thereby protecting the system from damages consequent to the fault. Is the second line of defence , which operates if the primary protection fails to activate within a definite time delay. Pilot wires refers to the wires that connect the CT’s placed at the ends of a power transmission line as part of its protection scheme. This is overcome by connecting adjustable resistors to pilot wires to get equipotential points on the pilot wires. • The method is simple (a) Only fault below the oil level are detected. 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Through neutral and earth a resistor is introduced between them Icon to know answer. This and act the limitations of Merz Price protection breakdown of the breaker itself to low! Of power system Interview will cover for protection the second line of relay. Wires on either sides of the important factors taken into consideration for selecting current! Based on annual revenues times that of air blast circuit breaker SF6 circuit breaker even for vibration, can. Not be published flow relay are used, the differential relay &.! Some specified period during running i.e is known as valence to symmetrical layers of ice formation: the. A false operation atmospheric pressure, its dielectric strength and excellent arc quenching medium surge the! Compensation testing Capacitance testing instruments used to activate within a definite time delay in and... Are over and power system protection interview questions fault conditions on either sides of the fault in!