c) Alternator d) All of these (d) none of the above. An instantaneous relay is one in which there is no time delay provided intentionally. c) The saturation voltage VCE for silicon transistor is same as that for germanium. Burden of a protective relay is the power. d) All of these A. Buchholz relay is a device which is used for the protection of transformer from its internal faults, it is a gas based relay. 3. c) Less than voltage element torque Although there is some time delay which can not be avoided. Answer.2. Directional relays are based on flow of (a) power (b) current (c) voltage wave (d) all of the above Ans: a. Switchgear and Protection MCQ Objective questions & answers are available for a Electrical Engineering students to clear various technical interview, competitive examination, and another entrance exam. For the protection of a very long extra high voltage line, the protective relay used is . Dec 27,2020 - Power Systems - MCQ Test 2 | 20 Questions MCQ Test has questions of GATE preparation. Relays for transmission line protection are. Multiple Choice Question (MCQ) of Electronics page-16:226. 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. B. Instantaneous relay having a setting of approximately 30% of motor rated current in the residual circuits of two CTs. In […] Explanation:-MHO relay is a high-speed relay and is also known as admittance relay. As the current coil is an inductor, there would be a certain delay to reach the current in the coil to its maximum value. Multiple Choice Question (MCQ) of Electronics page-13:181. Passes the frequencies lower than the specified cut off frequency Ans: (b). Multiple Choice Question (MCQ) of Electronics page-13:181. More specifically ideally there is no time required to operate the relay. (c) detect the fault current. Ans: (d), a) 0.0001 sec An over current relay, having a current setting of 125% connected to a supply circuit through a current transformer of ratio 400/5. Ans: (c), a) Impedance type d) 0.1 sec The conduction in JEFT is always by the What is meant by “Relay Settings”? There are various types of relay which can be considered as instantaneous relay. Here the fixed coil is fed from the circuit to be protected. Economics of Operation page-4, Objective Type Question or MCQ of B. This is a simplest example of instantaneous relay. a) Hinged armature type b) Polarized type c) Balanced beam type d) All of these Ans: (a) 35. 24. lt is well known that a long line is less stable than a short line; that is, a long line has a larger swing angle δmax compared to a short line. c) Number of ampere turns c) Free electrons are always present in the semiconductor. In an IDMT (inverse definite minimum time) relay, the operating principle is based on the idea that with the more severe a fault is, the faster it should be cleared to avoid damage to the apparatus. Inverse Time Over-current Relay. a. Which of the following statement is correct? b) Internal faults The relay must work efficiently to trip the circuit breakers if there are faults present. If the faults are severe it disconnects the transformer from the supply. d) The saturation voltage VCE for silicon transistor is lower than germanium transistor. What is protective relay? In which of the following device the base resistors are not added in the package but added externally? a) Majority carriers Full disclaimer here. d) Every internal faults b) Back up stop c) Holes The conduction in JEFT is always by the a) Majority carriers b) Minority carriers c) Holes b) 0.001 sec The slow developing faults called incipient faults in the transformer tank below oil level operate Buchholz relay which gives an alarm. Economics of Operation page-6, Objective Type Question or MCQ of B. B. There is also some time required for mechanical movement plunger in the relay. (b) normal condition. Ans: (b), a) Inter-turn fault whenever any internal fault occurs in a transformer, the Buchholz relay at once gives a horn for some time, if the transformer is isolated from the circuit then it stop its sound itself otherwise it trips the circuit by its own tripping mechanism. 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. Q. 40. b) CUJT Electrical Engineering Interview Questions Question 6. Fault current in relay coil / Pick up current. The Buchholz relay is a gas operated relay used for the protection of oil immersed transformers against all the types of internal faults. (of a relay) A term for contact operation (opening or closing) as a relay just departs from pickup. Ans: (c), a) Directional type Ans: (a), a) Load « Back CONTENTS Next » 1. Short Questions and Answers on Angle Modulation (FM and PM) Q.1. Economics of Operation page-2, Objective Type Question or MCQ of B. C. Rms value. Multiple Choice Questions with Answers on Refrigeration and Air-Conditioning - Set 07 Practice Test: Question Set - 07 1. The function of this relay is very fast. C. Ground wire. 1. Instantaneous overcurrent relay. 2. For example, dropout ratio of a typical instantaneous overvoltage relay is 90 percent. Although there is some time delay which can not be avoided. A. b) MHO type d) None of these c) Rotor faults Dec 24,2020 - Power Systems 2 MCQ | 20 Questions MCQ Test has questions of Electrical Engineering (EE) preparation. Multiple Choice Question (MCQ) of Electronics page-13:181. Angle modulation may be defined as the process in which the total phase angle of a carrier wave is varied in accordance with the instantaneous value of the modulating or message signal while keeping the amplitude of the carrier constant. An isolator is a device design to operates on (a) no load. Burden of a protective relay is the power (a) required to operate the circuit breaker (b) absorbed by the circuit of relay (c) developed by the relay circuit (d) none of the above Ans: b. b) Conductors (b) interrupt the circuit. An instantaneous relay is. (c) full load. 1.A single phasing relay can be used with, a) 1ɸ motor In a simple way electrical relay is shown in the figure above. Plug Setting Multiplier and is defined as the ratio of fault current in the relay coil to the pick up value. A. Circle passing through origin B. Circle with the centre at the origin C. Straight line passing through origin D. Straight line offset from the origin Due to unequal torques at two ends of the beam, it starts rotating against the hinge and ultimately closes the contacts of the relay. The Impedance relay is suitable for the phase faults relaying for the lines of moderate lengths Reactance type relays are employed for the ground faults while Mho type of relays are best suited for the long transmission lines and particularly where synchronizing power surge may occur. a) Inner electrons are always present in the semiconductor. a) The saturation voltage VCF of silicon transistor is more than germanium transistor. (Supervisory Control and Data Acquisition), Programmable Logic Controllers (PLCs): Basics, Types & Applications, Diode: Definition, Symbol, and Types of Diodes, Thermistor: Definition, Uses & How They Work, Half Wave Rectifier Circuit Diagram & Working Principle, Lenz’s Law of Electromagnetic Induction: Definition & Formula. An instantaneous relay is one in which there is no time delay provided intentionally. The normally open (NO) contacts of the relay are closed as soon as current in the fixed coil crosses the pick up value. The time of operation of such Relay is approximately 100 ms. Instantaneous Over-current relay is employed where the impedance between the source and the Relay is small as compared with the impedance of the section to be provided. The transient voltage that appears across the circuit breaker contacts at the instant of arc extinction. b) The saturation voltage VCE for germanium transistor is more than silicon transistor. c) Insulators d) Electrons Related Multiple choice questions: Analog Circuits multiple choice objective questions and answers part1 Analog Circuits multiple choice objective questions and answers part2 Say a relay has a time setting 0.1 and you have to calculate actual time of operation for PSM 10. Electrical4U is dedicated to the teaching and sharing of all things related to electrical and electronics engineering. b) Minority carriers The materials whose electrical conductivity is usually less than 1 × 106 mho/m are Also identifies the maximum value of an input quantity that will allow the relay to depart from pickup. Explain the working of an IDMT relay? c) 0.01 sec If you have any Questions regarding this free Computer Science tutorials ,Short Questions and Answers,Multiple choice Questions And Answers-MCQ sets,Online Test/Quiz,Short Study Notes don’t hesitate to contact us via Facebook,or through our website.Email us @ [email protected] We love to get feedback and we will do our best to make you happy. b) Greater than voltage element torque Here balance of one horizontally placed beam is disturbed due to pick up current in the relay coil. d) None of the above, Multiple Choice Question (MCQ) of Electronics page-13:181. Percentage differential relay. Which of the following statement is true? The highest frequency is 150Hz. d) Alloys, Multiple Choice Question (MCQ) of Electronics page-14:196. Long Transmission Line. b) External faults 23. ... Instantaneous value, rms value. Instantaneous relay should operate within. A. Normally a Time Setting Dial is provided which is calibrated from 0 to 1 s in step of 0.05 s. c) Both (a) and (b) Ans: (c), a) Equal to voltage element torque Directional relays are based on flow of (a) power (b) current (c) voltage wave (d) all of the above Ans: a 25. What do you mean by angle modulation? Decreased stability of the power system. 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Over current with extremely inverse characteristics . d) All of these Instantaneous Over-current Relay 2. a) Permanent moving magnet b) Induction cup c) Shaded pole d) Moving coil Ans: (a) 18. b) Non-directional type This adjustment is known as Time Setting Multiplier or TSM. b) Overhead line equipment Relay settings means actual value of the energizing or characteristic quantity at which the relay is designed to operate under given conditions. The magnetic strength of the electromagnet depends upon the current flows the coil conductors. These time delays are inherent in the instantaneous relay but no other time delay is intentionally added. Balance beam relay is also an well known example of instantaneous relay. c) Sense the fault and direct to trip the circuit breaker We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites. 10. More specifically ideally there is no time required to operate the relay. Ans: (c), a) Break the fault current This test is Rated positive by 85% students preparing for GATE.This MCQ test is related to GATE syllabus, prepared by GATE teachers. Multiple Choice Question (MCQ) of Electronics page-15:211. These relays can be operated in less than 0.1 sec. c) PUT 13) A low pass filter is. Definite Time Over-current Relay 3. d) All of these Ans: (a), a) Transformer 10) In an electromechanical relay, the necessity of connecting an external base resistance arises only _____ a. in the presence of an internal pull-up resistor b. in the absence of an internal pull-up resistor A. Such as, attracted armature relay where an iron plunger is attracted by an electromagnet to actuate the relay. Page-2 section-1 Learn Switchgear Protections MCQ questions & answers are available for a Electrical Engineering students to clear GATE exams, various technical interview, competitive examination, and another entrance exam. a) UJT b) 2r ɸ motor Multiple Choice Question (MCQ) of Electronics page-17:241. a. Burden of a protective relay is the power (a) required to operate the circuit breaker (b) absorbed by the circuit of relay (c) developed by the relay circuit (d) none of the above Ans: b 24. c) 3 ɸ motor C. Reactance type distance relay . From the time / PSM graph of the relay as shown below, we can see the total operating time of the relay is 3 seconds. Ans. Ans: (b), a) Air gap b) Bound electrons are always present in the semiconductor. Required to operate the circuit breaker. As the current coil is an inductor, there would be a certain delay to reach the current in the coil to its maximum value. 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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. 25. Therefore f max = 150Hz Nyquist rate = 2 f max = 2 * 150 = 300Hz. Threshold characteristics of a plain impedance relay in a complex Z plane is a . A Relay is generally provided with control to adjust the time of operation of the Relay.