220v AC rating. An RLC circuit carries an electrical circuit consisting of a resistor (R) and inductor (L) and a capacitor (C), connected in parallel or series. or 129. Thank you. Speed of the rotor of Resolution:ELCB is used to detect earth leakage fault. Electrical diversity factor is usually more than one. This voltage can then be displayed on an analogue or digital voltmeter, indicating frequency. 500 W. 120th St., Mudd 1310, New York, NY 10027 212-854-3105 ©2019 Columbia University To fix the reverse polarity, check the wire connection at the outlet and inspect your receptacle. They give operators the ability to monitor the both perturbations on the power supply, as well as power used within a building, or by a single machine or appliance. What is bus-bar? Both generator and alternator work on the same principle they convert mechanical energy into electrical energy. Your email address will not be published. What is the difference between earth resistance and earth electrode resistance? Why link is provided in neutral of an ac circuit and fuse in phase of ac circuit? uninterrupt power supply is mainly use for short time . Why computer humming sound occurred in HT transmission line? 5) Mention what are the different kind of cables used for transmissions? 18. No complex pitch changing mechanism is needed. synchronous machines have capability to work on different power factor(or say different imaginary pow varying the field emf. why? 111. Why use the VCB at High Transmission System ? ELECTRICAL Engineering Mcqs. 53. Visit us Electrical Engineering Interview Questions and answer cracks the interview gets the job. What is ACSR cable and where we use it? by varying the firing angle speed is controlled but in rheostatic control resistance is decreased by steps to achievespeed control. Resolution:In electronic circuits, the capacitor tolerance can be determined by a code that appears on the casing. How can you relate power engineering with electrical engineering? Reliability: It is the capacity of the power system to serve all power demands without failure over long periods. Calculate the voltage drop which will max 3% (resistance and reactance of cable found from 9. What are the advantages of star-delta starter with induction motor? 107. Thus there are “n” pulses per second, each with with a constant energy. Thus is due to negligible small leakage current. 98. what are the points to be consider for MCB(miniature circuit breaker selection? Interview selection in only based on that how you answer and represent your answer to the interviewer. 197. If the series current gets double then, the resistance is halved. 31. (B) the contact resistance of the surrounding earth to the electrode. It is usually expressed as a percentage of synchronous speed (Ns) and represented by the symbol ‘S’. SF6 is Sulpher hexa Flouride gas.. if this gas is used as arc quenching medium in a Circuitbreaker means SF6 CB. To minimize the current unbalance in the … All base load power plants have a high load factor. 112. Advantages of VSCF wind electrical system are: 137. So if any short circuits occur in the system first high currents bypassed in the Earthling terminal. Circuit Breaker is one which makes or breaks the circuit.It has two contacts namely fixed contact & moving contact.under normal condition the moving contact comes in contact with fixed contact thereby forming the closed contact for the flow of current. Resolution:It depends upon R=rho l/a where area(a) is inversely proportional to resistance (R), so if (a) increases, R decreases & if R is less the leakage current will take low resistance path so the earth pin should be thicker. It is used in oil filled transformers, some types of high voltage capacitors, fluorescent lamp ballasts, and some types of high voltage switches and circuit breakers. 70. So one should brush up and update their technical knowledge by knowing the latest updates in the electrical field by knowing Interview Questions on Electrical. Resolution:Knee point voltage is calculated for electrical Current transformers and is very important factor to choose a CT. The voltage induced in secondary coil is known as mutually induced voltage. Which type of A.C motor is used in the fan (ceiling fan, exhaust fan, pedestal fan, bracket fan etc) which are find in the houses ? Why we use ac system in India why not dc ? Switch mode power converter can be used in the following 5 different ways. Before the signal is transmitted, it is converted into digital form. The Zener-breakdown occurs in heavily doped junctions, which produce narrow depletion layers. What is the difference between delta-delta, delta-star transformer? What is “pu” in EE? if it is dc generator, it will supply dc to the rotory poles through slip ring and brushes( conventional alternator). Zener-breakdown or Avalanche breakdown may occur independently or both of these may occur simultaneously. alternator, can be steam turbines,or hydro turbines .When poles of the rotor moves under the armature Laser diodes are compact transistor like packages with two or more electrical leads. 178. Due to the sudden change of supply the chock will generate around 1000 volts . Electrical Engineering Interview Questions. The different methods of starting an induction motor. State the difference between generator and alternator? Questions regarding Ohm's law, circuit-related theorems, mutual induction, and the like are frequently asked of anyone wishing to become an engineer. for railways,trams, trolleys etc). So delta / star transformer is used for lighting loads. Battery banks are in connected in series or parallel and why? The armature flux may support main flux or opposes main flux. We can protect the equipment also. Technical electrical engineering interview questions are among the most frequently asked of a potential employee. Interposing current transformer are equipped with a wide range of taps that can be selected by the user to achieve the balance required. KVAR means “Kilo Volt Amperes with Reactive components”. ? onload automatic device used for breaking the circuit in case of abnormal conditions like short circuit, overload etc., it is having three specification 1 is rated current and 2 is short circuit breaking capacity and 3 is instantaneous tripping current. 16589+ Electrical Engineering interview questions and answers for freshers and experienced. What is the function of interposing current transformer? Desired results are obtained by either trimming the layer thickness or by cutting helical grooves of suitable pitch along its length. 43. 119. Since the power factor of transformer is dependent on load we only define VA rating and does not include power factor .In case of motors, power factor depend on construction and hence rating of motors is in KWatts and include power factor. What is the main use of rotary phase converter ? What is stepper motor.what is its uses? Electron in the outer orbit is known as valence. generators are used for the production of electricity? This reduces the amount of noise injected into the amplifier, because any noise appearing simultaneously on both the input-terminals as the amplifying circuitry rejects it being a common mode signal. When supply is provided ,the starter will interrupt the supply cycle of AC. Enlist types of dc generator? Resolution:The main function of an interposing current transformer is to balance the currents supplied to the relay where there would otherwise be an imbalance due to the ratios of the main current transformers. Hence, according to Faraday’s laws of electromagnetic induction, emf will be induced in both the windings. There are a Transformer and an induction machine. Near distribution transformers and out going feeders of 11kv and incomming feeder of 33kv and near power transformers in sub-stations. • Reliability, Again in extrinsic semi-conductors you will have N-type semiconductors and P-type semiconductors. What is the significance of vector grouping in Power Transformers? 32. Considering this condition actual current currying capacity of cable reduce than current currying capacity (which given to cable Catalogue) this is called derating. 52. 128. Define the following: Average demand, Maximum demand, Demand factor, Load factor. 3) Define the term Capacitance and Inductance? waiting for your great help to me settle in future. Explain What is rated speed? 122. I have a test in oil and gase company as a electrical engineer after some days.please guide me the preparation for this test. What are HRC fuses and where it is used? Desired results are obtained by either trimming the layer thickness or by cutting helical grooves of suitable pitch along its length. In order to find the second terminal we should recourse to its definition: Earth Resistance is the resistance existing between the electrically accessible part of a buried electrode and another point of the earth, which is far away. 540/11000= I2/2334 6. Volt Amps with Reactive component. 78. wire or due to 0 psi. Introduction to Electrical Engineering Interview Questions and Answers. step down an unregulated dc input voltage to produce a regulated dc output voltage using a circuit known as Buck Converter or Step-Down SMPS. Following motors are used: –. When a string of resistors in a series will divide the source voltage into proportion to their values. 127. 54. The armature flux has an important role for the running condition. MCCB moulded case circuit breaker and is thermal operated for over load current and magnetic operation for instant trip in short circuit condition.under voltage and under frequency may be inbuilt. step up or step down an unregulated dc input voltage to produce a regulated dc output voltage, invert the input dc voltage using usually a circuit such as the Cuk converter, and. and p.t. These photons hit back and forth between the back and front mirror, and hence a diverging beam emits from the laser diode packages. Differential Amplifier: The amplifier, which is used to amplify the voltage difference between two input-lines neither of which is grounded, is called differential amplifier. it should not be operated while it is having load. Aero turbine always keeps going at maximum efficiency point. Explain different losses in a transformer. Slip can be defined as the difference between the flux speed (Ns) and the rotor speed (N). A fixed width pulse is generated for each cycle. 65. 7. whats is MARX CIRCUIT? Hence, voltage is induced in both the windings. Explain forward resistance, static resistance and dynamic resistance of a pn junction diode. Explain How to determine capacitor tolerance codes? 64. networks . (p.u=actual value/base value). Behavioral Interview. 186. we connect large capacitor bank in series to improve the voltage power supply at the load end in balanced transmission line when there is considerable voltage drop along the balanced transmission line due to high impedance of the line.So in order to bring the voltage at the load terminals within its limits (i.e (+ or – %6 )of the rated high terminal voltage )the large capacitor bank is used in series. Can we measure over voltage and over current by measuring current only? Do you think there’s any direct link between power engineering and electrical engineering? Plant cost for AC transmission (circuit breakers, transformers etc) is much lower than the equivalent DC transmission Star delta starter circuit comes in circuit first during starting of motor, which reduces voltage 3 times, that is why current also reduces up to 3 times and hence less motor burning is caused. 1) What happens when two positively charged material is placed together? 67. It is easy to maintain and change the voltage of AC electricity for transmission and distribution. At the time of motor taking normal current (rated current)the speed of the motor is called rated speed. Resolution:In DC motors, Voltage equation is V=Eb-IaRa (V = Terminal voltage,Eb = Back emf in Motor,Ia = Armature current,Ra = Aramture resistance).At starting, Eb is zero. General questions for electrical engineers include questions pertaining to your degree or degrees, your employment history, and your reasons for pursuing your career. c. From power stations, AC is produced so it is better to use AC then DC instead of converting it. What is vacuum circuit breaker.define with cause and where be use it Device? thirdly the cost of plant associated with AC transmission (circuit breakers, transformers etc) is much lower than the equivilant of DC transmission AC transmission provides a number of technical advantages. I(L)*1.25=I(MAX) maximum current. Power engineering is a sub division of electrical engineering. Over current relay meant for sensing any With an additional 75 professionally written interview answer examples. If we give 2334 A, 540V on Primary side of 1.125 MVA step up transformer, then what will be the Secondary Current, If Secondary Voltage=11 KV? How to calculate capacitor bank value to maintain unity power factor with some suitable example? 165. 41. Its ratio between insulation resistance(IR)i.e meggar value for 0min to insulation resistance for min. now there is no change of supply causes choke voltage normalized and act as minimize the current. A receptacle with reverse polarity will have the white wire screwed to the hot side and the black wire will be connected to the neutral side, if that the case swap the wires and it will resolves the problem. Copper loss is a constant after the coil has been wound and therefore a measurable loss. TRANSFORMER LOSSES – Transformer losses have two sources-copper loss and magnetic loss. For the generation of elect power we need a prime mover which supplies mechanical power input to the MOSFET’s have input impedance much higher than that of JFET’s. 34. what its purpose ? The water is obtained in the boiler and the coal is burnt so that steam is obtained this steam is allowed to hit the turbine , the turbine which is coupled with the generator generates the electricity. At first calculate the electrical current of the load, after that derate the electrical current considering derating factor(depending on site condition and laying of cable) after choose the cable size from cable catalog considering derating electrical current.After that measure the length of cable required from supply point of load to load poin. Define IDMT relay? 191. It’s possible by means of Electronic chokes,otherwise it’s not possible to ionize the particles in tube light with normal voltage. Nowadays, the character sketch of the person is more important for success of the business as a whole. • Maximum demand, This is a must know question for any good Electrical Engineer. if it is greater than 1 then load will act as capacitor and starts feeding the source and will cause tripping. 83. Now a days, magnetic traction is also used for bullet trains.and basically dc motors are used for electric traction systems. Thin film resistors- It is constructed as a thin film of resistive material is deposited on an insulating substrate. The choice of electrical system for an aero turbine is guided by three factors: 183. What are the different methods for the starting of a synchronous motor. The aiding emf is dynamically induced into the coils undergoing commutation by means of compoles or interpoles, which are series excited by the armature current. During abnormal & faulty conditions(when current exceeds the rated value) an arc is produced between the fixed & moving contacts & thereby it forms the open circuit Arc is extinguished by the Arc Quenching media like air, oil, vacuum etc. 145. High-tension cables can transmit voltage upto 23000 volts. Series motor are used in Trains, Crane etc. nasiruol@gmail.com. Advantages of VSCF wind electrical system are: 184. The current currying of cables will change depending upon the site temperature (location of site), type of run (it will run through duct, trench, buried etc. It is the voltage at which a CT gets saturated. The code may serve any of a number of purposes such as compressing information for transmission or storage, encrypting or adding redundancies to the input code, or translating from one code to another. If their is high power factor, i.e if the power factor is close to one: 19. whats the one main difference between UPS & inverter ? Pu stands for per unit in power system. various mediums are used to quench this arc in respective CB’s. #d= DESIRED P.F. 136. Give their applications Mcb specification are done on maximum current flow in circuit. I want a learnership of electrical engineering I complete my N6. 72. Starting methods: Synchronous motor can be started by the following two methods: 161. Here we have provided the best 50 important electrical engineering interview questions that can be asked by the interviewer in your technical job interview. Sir am completing my electrical engineering diploma this year ….can you send me a PDF of questions answers for my first interview preparation I will be very thankful to you…. The reason that 4ma is chosen instead of 0 mA is for fail safe operation .For example- a pressure instrument gives output 4mA to indicate 0 psi, up to 20 mA to indicate 100 psi, or full scale. It is given by Voc / (Ri + RL). Most of the time the last digit tells you how many zeros to write after the first two digits and these are read as Pico-Farads. so kindly please send me pdf to my mail id nokia.sagar4@gmail.com. When two positively charged material place together it will repel. Dear engineers WhatsApp:- 7890212165, sir I am preparing junior engineer so plz send me all important MCQ & answer in PDF file, Hi State the difference between generator and alternator (anupnandi231@gmail.com) Actually the thing is vacuum has high arc quenching property compare to air because in VCB ,the die electric strengths equal to 8 times of air . 144. Thus it can control the output Reactive Power of the Generator. Explain What is use of lockout relay in ht voltage? 77. Only one of the terminals is evident in the earth resistance. Ex : 24 nos. Tell me in detail about c.t. It is usually expressed as a percentage of Junctions that experience breakdown above 5v are caused by avalanche-effect. 132. What is the difference between surge arrestor and lightning arrestor? Please look at our Electronics and Communications Engineering jobs interview questions and answers page to rock in your interview. 1 ton is equal to how many watts? 17. An electrical engineering company asks a lot of interview questions in the technical round. The machine is started as a squirrel cage induction motor first. Give two basic speed control scheme of DC shunt motor? Esters are non-toxic to aquatic life, readily biodegradable, and have a lower volatility and higher flash points than mineral oil. By connecting static capacitors in parallel with the load operating at lagging power factor. What are the advantages of VSCF wind electrical system? What is an exciter and how does it work? What is reverse power relay? Name the types of motors used in vacuum cleaners, phonographic appliances, vending machines,refrigerators, rolling mills, lathes, power factor improvement and cranes. In electronic regulator triac is employed for speed control. When we connect the large capacitor bank in series ? Then rotor poles are excited due to which the rotor field is locked with the stator-revolving field and continuous rotation is obtained. The motor which work or act on the applied input pulse in it, is called as stepper motor.This stepper motor is under the category of synchronous motor, which often does not fully depend of complete cycle. If the resistance total in a series circuit doubles the current will reduce to half. 82. What is meant by regenerative braking? Use of switch mode power converter in real-time basis? The code is a letter that often follows a three-digit number (such as 130Z).The first two are the 1st and 2nd significant digits and the third is a multiplier code. State the factors, for the choice of electrical system for an aero turbine. Resolution:Since two bulbs are in series they will get equal amount of electrical current but as the supply voltage is constant across the bulb(P=V^2/R).So the resistance of 40W bulb is greater and voltage across 40W is more (V=IR) so 40W bulb will glow brighter. The point of technical questions is to test how you go about answering the question, rather than if … n in an Electric train during running , We did nt feel any Shock ? When JFET is operated with a reverse-bias on the junction, the gate-current IG is larger than it would be in a comparable MOSFET. Transistors are comprised of several combination of n-type and p-type semi-conductors. Firstly I would like to say thank you for all your great work .Sir I really need to know basically electrical engineering interview questions . 71. The main advantage of using the star delta starter is reduction of current during the starting of the motor.Starting current is reduced to 3-4 times Of current of Direct online starting. why earth pin diameter is higher than other two pin? Extra energy in the high wind speed region of the speed – duration curve can be extracted. JFET’s can only be operated in the depletion mode whereas MOSFET’s can be operated in either depletion or in enhancement mode. Advantages : 10. This includes the maximum power from the network and in this case the load resistance is being is equal to the resistance of the network and it also allows the resistance to be equal to the resistance of the network. What are your strengths and weaknesses? A breaker is normally used to break a circuit. KVAR= KW(TAN(COS(-1)#e)- TAN(COS(-1)#d) ) but in VCB the medium is vacuum gas. 89. highlight its significance. By using flux control method:in this method a rheostat is connected across the field winding to control the field current.so by changing the current the flux produced by the field winding can be changed, and since speed is inversely proportional to flux speed can be controlled .armature control method:in this method a rheostat is connected across armature wdg.by varying the resistance the value of resistive drop(IaRa)can be varied,and since speed is directly proportional to Eb-IaRa the speed can be controlled. There are normally three types of power are counted in electrical power. This reversal of current in a coil is called commutation. 30. Aero turbine rotational speed: constant speed with variable blade pitch, nearly constant speed with simpler pitch- changing mechanism or variable speed with fixed pitch blades. Wire is sized by American Wire Gauge system. 24. Lasing occurs when stimulated emission results into the amplification of photon confined to the lasing mode. Speed of the rotor of an induction motor is always less than its synchronous speed. Depending on the job you're interviewing for, you will be asked about the skills, experience, certifications, competencies, language, processes, systems, and tools you have that are a match for the job requirements. Once the phase and neutral are connected in an ELCB, the current will flow through phase and that much current will have to return neutral so resultant current is zero. And electrical engineering & electronics engineering ? uninterrupt power supply is mainly use for short time . By putting these value on Relation- It allows control of the power flow between two Fuses are used in only one time but breakers are used by multiple number of times. Working principle of operation of a single-phase transformer can be explained as An AC supply passes through the primary winding, a current will start flowing in the primary winding. Capacitor is load free component but why ampere meter shows current when capacitor bank breaker close? d. When a large fault occurs in a network, it is easier to interrupt in an AC system, as the sine wave current will naturally tend to zero at some point making the current easier to interrupt. This effect of supporting and opposing of main flux to armature flux is called armature reaction. What’s electric traction? 15) Explain what does a string of resistors in a series will do? With size of the equipment( transformer or alternator)and selection of relying system earthing will be further classified into directly earthed,Impedance earthing, resistive (NGRs) earthing. Quality factor q depends on frequency and bandwidth. 29. It is the property of a cable by virtue of it can withstand the applied voltage without rupturing it is known as insulation level of the cable. Both have the same principle of electromagnetic induction, the only difference is that their construction. Electrical Engineer Interview Questions: Some Common Important Electrical Engineering Interview Questions for fresher and experienced candidate Learn both. a. The difference between the electronic and ordinary regulator is the fact that in electronic reg. Sir, can you mail me this in PDF format at sajid.harun@gmail.com. Hence syn. Every power transformer has a vector group listed by its manufacturer. Why AC systems are preferred over DC systems? Power engineers may work on the design and maintenance of the power grid i.e. Explain the working principal of the circuit breaker? Where should the lighting arrestor be placed in distribution lines? Excitation is applying an external voltage to DC shunt coil in DC motors. ACSR means Aluminium conductor steel reinforced, this conductor is used in transmission & distribution. 108. 99. What is derating?, why it is necessary, it is same for all means for drives, motors,and cables. Electrical Engineer Interview Questions. 118. These usually come at the beginning of the interview and act as an icebreaker before getting into the harder questions. No.We can’t sense the over voltage by just measuring the current only because the current increases not only for over voltages but also for under voltage(As most of the loads are non-linear in nature).So,the over voltage protection & over current protection are completely different. What is SF6 Circuit Breaker? If it persists, a licensed electrician will be needed. a. (Company:reliance) What is the use of stepper motor? 2. Reserve generating capacity: Extra generation capacity installed to meet the need of scheduled downtimes for preventive maintenance is called reserve-generating capacity. E -Induced emf per phase For wires, smaller the wire gauge larger the ampacity or capacity of the wire to handle current. Control Systems-Electrical Engineering Interview Questions ; Question 10. synchronous machines have capability to work on different power factor(or say different imaginary power varying the field emf. Normally they have low resistance. whether it should be high or low? 193. and this lighting load is always unbalanced in all three phases. but inverter is start with 2v,24,dc to 36v dc and 20amp to 80amp battery with long time backup. These losses depend upon the loading conditions of the transformers. give the power necessary for that particular speed but in case of ordinary rheostat type reg. indra_039@yahoo.com This is one of the commonly asked interview questions for freshers from the electrical engineering background. Its true that if birds touch the single one line (phase or neutral) they don’t get electrical shock… if birds touch 2 lines than the circuit is closed and they get electrical shock.. so if a human touch single one line(phase) then he doesn’t get shock if he is in the air (not touching – standing on the ground if he is standing on the ground then touching the line (phase) he will get a shock because the ground on what we standing is like line (ground bed – like neutral)? Few advantages of storage batteries are mentioned below: 160. while breaking the circuit, the contact terminals will be separated. In some situations, equipment function and operation is monitored and controlled from a remote location where communication is via modem, or highspeed My Email address :- bagchitapas@gmail.com WhatsApp:- 7890212165 Isolator is a off load device which is used for isolating the downstream circuits from upstream circuits for the reason of any maintenance on downstream circuits. Link is provided at a Neutral common point in the circuit from which various connection are taken for the individual control circuit and so it is given in a link form to withstand high Amps. Pu stands for per unit and this will be used in single line diagram of power distribution and it is like a huge electrical circuit with no of components (generators, transformers, loads) with different ratings (in MVA and KV). At the time of separation an air gap is formed in between the terminals. A direct-current torque motor is mounted on the same shaft. This effect is called as Corona effect, and it is considered as power loss. The output terminals are equivalent to the constant source of current and it allows giving the parallel resistance. What are the types of power in electrical power? Generator persists stationary magnetic field and rotating conductor which rolls on the armature with slip rings and brushes riding against each other, hence it converts the induced emf into dc current for external load whereas an alternator has a stationary armature and rotating magnetic field for high voltages but for low voltage output rotating armature and stationary magnetic field is used. 93. 84. To minimize the current unbalance in the primary we use delta winding in the primary. 110. 58. 2) What is referred to the electron in the outer orbit? Why in a three pin plug the earth pin is thicker and longer than the other pins? b. As the coil moves into the influence of the next pole- pair, the current in it must reverse. 2. CMRR: It can be defined as the ratio of differential voltage-gain to common made voltage gain. The avalanche breakdown occurs in lightly doped junctions, which produce wide depletion layers. What happens if i connect a capacitor to a generator load? What types domain of Laplace transforms? 196. In an AC system this becomes much easier to interupt, as the sine wave current will naturally tend to zero at some point making the current easier to interrupt. 16) What is meant by reverse polarity and how it can be fixed? For example, low voltage lighting and lamp cords will have 18 gauge, electric furnaces or large electric heaters are of 6 gauge. it also reduces over heating of transformers. 105. Question: What is the difference between an analog circuit and a digital circuit, and which one is more flexible?. Actually the thing is vacuum has high arc quenching property compare to air because in VCB ,the die electric strengths equal to 8 times of air . Two bulbs of 100w and 40w respectively connected in series across a 230v supply which bulb will glow bright and why? This reduces the amount of noise which is injected into the amplifier, because any noise appearing simultaneously on both the input-terminals as the amplifying circuitry rejects it being a common mode signal. 104. 57. Cables are categorized into three forms according to its thermal capacity. For lighting on steam and diesel railways trains. means according to ups VA it gives backup. generators r used for the production of electricity. With this,in case of unbalanced loading neutral will not be shifted.so that unbalanced voltages will not arise. They are. 162. so it is necessary to test this devices for temperature rise. f -frequency 21. A two phase motor is often a motor with the the starting winding and the running winding have a phase split. 14) What happens if the series current double? Phonographic appliances – Hysteresis motor. By means of an auxiliary motor: The rotor of a synchronous motor is rotated by auxiliary motor. e.g;ac servo motor.where the auxiliary winding and the control winding have a phase split of 90 degree. How you performed during your graduation/post-graduation is a good enough measure for the interviewer to understand how well you will perform on the job. dear respected sir, i am unemployed student in andhra pradesh. its specification only rated current is given.But circuit breaker is The relay itself may have up to 24 contact points within the unit itself. Today, non-toxic, stable silicon-based or fluoridated hydrocarbons are used, where the added expense of a fireresistant liquid offsets additional building cost for a transformer vault. But in the case of Fuse in the Phase of AC circuit it is designed such that the fuse rating is calculated for the particular circuit (i.e load) only.So if any malfunction happen the fuse connected in the particular control circuit alone will blow off. In motors at the time of starting the armature resistance is introduced to reduce the high starting current and the field resistance is kept minimum to have high starting torque. Why can’t use ACB? This allows the control power for multiple machines to be locked out by the turn of a single key switch. JFET’s have characteristic curves more flat than that of MOSFET is indicating a higher drain resistance. How to determine alternating current frequency? If yes, then what is it? So it should be zero lagging like inductor. can u please send me the pdf form. really important for me.plz send me the question and answer. Electric traction means using the electric power for traction system (i.e. Can i get it through mail . To bring all the ratings into common platform we use pu concept in which, in general largest MVA and KV ratings of the component is considered as base values, then all other component ratings will get back into this basis.Those values are called as pu values. What is different between resistance grounding system and resistance earthing system? Why Delta Star Transformers are used for Lighting Loads? and is of sinusoidal in nature…due to polarity change of rotor poles(i,e) N-S-N-S. 69. Bus bars and isolators are rated for continuous power flow, that means they carry heavy currents which rises their temperature. Its functions are to insulate, suppress corona and arcing, and to serve as a coolant. This requires a large conductor size. So,I2 = 114.5 Amps. Different type of DC motors and their applications are as follows:-. Which type of motor is used in trains, what is the rating of supply used explain Working principal? Larger generators and transformers are required. The term C.T means current transformer,and the term P.T means potential transformer.In circuit where measurements of high voltage and high current is involved they are used there.Particularly when a measuring device like voltmeter or ammeter is not able to measure such high value of quantity because of large value of torque due to such high value it can damage the measuring device.so, CT and PT are introduced in the circuits. Often the advantages of 3 phase motors, and other 3 phase equipment, make it worthwhile to convert single phase to 3 phase so that small and large consumers need not want to pay for the extra cost of a 3 phase service but may still wish to use 3 phase equipment. The complete wire wound resistor is coated with an insulating material such as baked enamel. Because Current flow in the conductor is inversely proportional to the conductor diameter. Resolution:For lighting loads, neutral conductor is must and hence the secondary must be star winding. 185. 49. They lead engineering teams, prepare drawings, write reports, and train new engineers. In a JFET, if the gate is forward-biased, excess-carrier injunction occurs and the gatecurrent is substantial. The complete wire wound resistor is coated with an insulating material such as baked enamel. What to look for in an answer: Whether the candidate seems engaged in the idea of answering the question; If the candidate gives thought to a purposeful answer What is 2 phase motor? This resistance can be viewed by the output terminals and the energy sources can be removed by leaving the internal resistance behind. This circuit is called a second order circuit as any voltage or current in the circuit can be described by a second order differential equation. This is the largest collection of Electrical Engineering Questions and Answers for Technical Interview, Campus Interview and Placement Tests. The two types of earthing are Familiar as Equipment earthing and system earthing. One is terminal active network containing voltage sources. State Maximum power transfer theorem 15. Reverse polarity is referred in a condition where one or more of your receptacles are connected incorrectly. 11. what is the principle of motor? and in the most of electric lines the neutral is grounded..so that means that human who touch the line closes the circuit between phase and neutral. The induced emf developed when the rotating conductors of the armature between the poles of magnet, in a DC motor, cut the magnetic flux, opposes the current flowing through the conductor, when the armature rotates, is called back emf. How to Answer: Power engineering and electrical engineering might sound very different but they do have a direct link with each other. Power factor should be high in order to get smooth operation of the system.Low power factor means losses will be more.it is the ratio of true power to apparent power. an induction motor is always less than its synchronous speed. What is meant by insulation voltage in cables? This flux is linked with primary and secondary windings. For the operation of protective devices and for emergency lighting at generating stations and substations. 62. Secondly it is much easier to change the voltage of AC electricity for transmission and distribution. It is longer because the The First to make the connection and Last to disconnnect should be earth Pin. During this process, the value of the resistance is monitored closely and cutting of grooves is stopped as soon as the desired value of resistance is obtained. Why did you decide to become an electrical engineer? Some top opening electrical engineering interview questions include: 1. Why the capacitors works on ac only? Connecting a capacitor across a generator always improves power factor,but it will help depends up on the engine capacity of the alternator,other wise the alternator will be over loaded due to the extra watts consumed due to the improvement on pf. 96. A lock-out relay is generally placed in line before or after the e-stop switch so the power can be shut off at one central location. Why use the VCB at High Transmission System ? My Mail ID : nayeem_eee@hotmail.com. Dc series is in the trains to get high starting torque while starting of the trains and operating voltage is 1500v dc. CMRR: It can be defined as the ratio of differential voltage-gain to common made voltage gain. Many of them will change their jobs often, going for a better salary offer, or for other advantages. 2V,200Ah batteries connected in series will give 48V,200Ah output (AH = Ampere hours). 39. 44. online ups having high volt and amp for long time backup with with high dc voltage.but ups start with v dc with 7 amp. Generator and alternator are two devices, which converts mechanical energy into electrical energy. 37. That y always vacuum used as inHT breaker and air used as in LT . 9) Mention what are the types of semi-conductors? AC or Dynamic Resistance: It can be defined as the reciprocal of the slope of the forward characteristic of the diode. Give two basic speed control scheme of DC shunt motor? Explain what are inter-poles and why they are required in a dc machine. but inverter is startwith v,24,dc to 36v dc and 0amp to 180amp battery with long time backup. once the current passes through the tube the starter circuit will be out of part. They also participate in ongoing education. means according to ups VA it gives backup. How electrical power is generated by an A.C Generator? Firstly, the output of power stations comes from a rotary turbine, which by it’s nature is AC and therefore requires no power electronics to convert to DC. If we connect tapings to low voltage side, sparks will produce while tap changing operation due to high current. That’s why the ac solenoid attract the plunger even though it’s terminals are interchanged. 134. Define stepper motor. so, interchanging of terminals in ac system does not show any difference. It’s possible with Electronic choke. When two positively charged material place together it will repel. 100. How does Zener phenomenon differ from Avalanche breakdown? So high electrical current will flow through primary side of the transformer.So for this reason coil and insulation will burn out. Will the poles changes? The motor has max load current compare to that of transformer because the motor consumes real power.. and the transformer is only producing the working flux and its not consuming.. hence the load current in the transformer is because of core loss so it is minimum. Power factor improvement – Synchronous motors. Dear sir please send to me some pdf file of Transformer and motors and elevator . 17) Explain what rectifiers is and what are the types of rectifiers? Answer : An encoder is a device used to change a signal (such as a bitstream) or data into a code. 61. preparing for competating exams.i followed your questions .it was very usefull to me. When it picks up speed, excitation is given to the rotor and the rotor starts rotating continuously as the rotor field is locked with stator revolving field. Low lagging power factor causes a large voltage drop, hence extra regulation equipment is required to keep voltage drop within prescribed limits. called on grid systems and they might work on off grid systems that are not connected to the system. 76. Practice 25 Electrical Technician Interview Questions with professional interview answer examples with advice on how to answer each question. This method is more suitable than a direct counter, as it can get good accuracy in a second or so. 130. whats the one main difference between UPS & inverter ? Mention the methods for starting an induction motor? An encoder is a device used to change a signal (such as a bit stream) or data into a code. Why back emf used for a dc motor? Firstly I would like to say thank you for all your great work .Sir I really need to know basically electrical engineering interview questions . Review a list of frequently asked Electrical interview questions for electrical graduates. explain it? So always transmission voltage is multiple of 11. The phenomenon when the depletion region expands and the potential barrier increases leading to a very high electric field across the junction, due to which suddenly the reverse current increases under a very high reverse voltage is called Zener effect. > 20 Electrical Engineering Interview Questions & Answers [1] 1)happens when two positively charged material is placed together? These are also very important for your lab viva in university exams like JNTU, Andhra,OU,Anna university,Pune,VTU,UPTU,CUSAT etc. Sir, Please send me Electrical Engineering Interview Questions. Cables, which are used for transmitting power, can be categorized in three forms: 146. Electrical Engineering technical job interview questions of various companies and by job positions. Define the following terms:- 1 ton = 12000 BTU/hr and to convert BTU/hr to horsepower, 12,000 * 0.000929 = 4.715 hp therefore 1 ton = 4.715*.746 = .5 KW. Your installation of conductors will depend on a few factors like gauge of the wire, wire capacity, etc. Constant losses or Iron losses: The losses that occur in the core are known as core losses or iron losses. The motor generator set can used in the following different ways: 91. 199. 106. 87. What is inrush current? Sir, its just an extra-ordinary piece of compilation. State the methods of improving power factor? Power Quality meters are common in many industrial environment. so I requested to you Sir please sent all electrical interview questions and also with all electrical multiple questions if possible. This assures Safety for the person who uses the electrical instrument. Forward Resistance: Resistance offered in a diode circuit, when it is forward biased, is called forward resistance. Define what is difference between fuse and breaker? 4. (CT-current transformer). 4) Mention what is the difference between generator and alternator? T -number of turns The effect of armature flu to main flux is called armature reaction. according to Lenze’s law it will oppose the cause i.e. Several of these general engineer interview questions are behavioral questions, that ask you how you have acted during a given situation in the past. How tube light circuit is connected and how it works? 90. Most efficient form of storing energy portably. 117. more current(V constant),result in more losses if pf is good ex: 0.95 to meet actual power load has to draw less current(V constant),result in less losses). 120. 163. The KVAR indicates the electrical power. What is use of lockout relay in ht voltage? 6) Mention what are the different colors on wires indicates? What is the voltage gain or transfer function of amplifier? Senior Electrical Engineers design, develop, maintain, inspect, and evaluate electrical components and machinery. the power wastage is same for every speed and no power is saved. please sent me electrical interview Question. Resolution:Isolators are mainly for switching purpose under normal conditions but they cannot operate in fault conditions .Actually they used for isolating the CBs for maintenance. 114. conductors which are placed on the stator ,field flux cut the armature conductor ,therefore voltage is generated phi -maximum flux per pole 12. The Norton’s theorem also explains about the constant current that is equal to the current of the short circuit placed across the terminals. Both have the same principle of electromagnetic induction, the only difference is that their construction. The reversal of current is opposed by the static coil emf and therefore must be aided in some 139. Several coils undergo commutation simultaneously. step up an unregulated dc input voltage to produce a regulated dc output voltage using a circuit known as Boost Converter or Step-Up SMPS. Difference between a four point starter and three point starter? 121. it is one type of synchronous motor which runs in steps in either direction instead of running in complete cycle.so, in automation parts it is used. A choke is connected in one end of the tube light and a starter is in series with the circuit. What is the difference between isolators and –>electrical circuit breakers? VCB’s can be used up to kv. it is manually operated and does not contain any solenoid unlike circuit breaker. MCB is miniature circuit breaker which is thermal operated and use for short circuit protection in small current rating circuit. (adsbygoogle = window.adsbygoogle || []).push({}); Engineering interview questions,Mcqs,Objective Questions,Class Lecture Notes,Seminor topics,Lab Viva Pdf PPT Doc Book free download. Wire wound resistors – length of wire wound around an insulating cylindrical core are known as wire wound resistors. As such, the idea of interviewing engineers can become daunting. Frequently asked interview questions with answers under the subjects like electrical machines,Transmission and distribution,Power electronics and some general basic questions. Hence syn. What is the Polarization index value ? 13) What will be the current if the resistance total in a series circuit doubles? This computer humming sound is coming due to ionization (breakdown of air into charged particles) of air around transmission conductor. whenever any internal fault occurs in a transformer, the boucholz relay at once gives a horn for some time, if the transformer is isolated from the circuit then it stop its sound itself other wise it trips the circuit by its own tripping mechanism. the voltage across the two terminals when RL is removed) and sum of load resistance and internal resistance of the network. Electrical Engineering is a branch and discipline of electrical concepts and its applications related to electrical systems, electromagnetic and electronic devices. Explain the operation of variable frequency transformer? This is usually done by means of a programmed algorithm,especially if any part is digital, while most analog encoding is done with analog 143. Hysteresis loss is constant for a particular voltage and current. Compare JFET’s and MOSFET’s. What is the difference between electronic regulator and ordinary electrical rheostat regulator for fans? What is the power factor of an alternator at no load? The shunt connection in four point stater is provided separately form the line where as in three point stater it is connected with line which is the drawback in three point stater. 5. 126. 75. body ( non conducting part)of the equipment shouldd be earthed to safegaurd the human beings.system Earthing : In this neutral of the supply source ( Transformer or Generator) should be grounded. 42. Why electricity in India is in the multiples of 11 like 11kv, 22kv, 33kv ? b. There are two types of semi-conductors intrinsic and extrinsic. 2. for this purpose it mainly used in automation parts. Hence the starting current is reduced , the voltage drops during the starting of motor in systems are reduced. Why most of analog o/p devices having o/p range 4 to 20 mA and not 0 to 20 mA? Also, explain CMRR. Storage batteries are used for various purposes, some of the applications are mentioned below: 149. The types of rectifiers are. Generator and alternator are two devices, which converts mechanical energy into electrical energy. Why we do 2 types of earthing on transformer (ie:)body earthing & neutral earthing , what is function. What is power factor? 40. Explain the terms real power, apparent power and reactive power for ac circuits and also the units used. The pulses are integrated (filtered or averaged) to get a steady DC voltage which is proportional to frequency. Define What is the function of anti-pumping in circuit breaker? Electrical Interview Questions & Answers visit www.eeekenya.com Page | 5 Answer: For lighting loads, neutral conductor is must and hence the secondary must be star winding and this lighting load is always unbalanced in all three phases. Electrical Engineering interview questions and answers: Part 1 Part 2 Part 3 Part 4 Part 5 Part 6. Explain the application of storage batteries. Why can’t use ACB? Why AC systems are preferred over DC systems? Generally capacitor gives infinite resistance to dc components(i.e., block the dc components). Availability: As the percentage of the time a unit is available to produce power whether needed by the system or not. Inrush current is the current drawn by a piece of electrically operated equipment when power is first applied. From the equation we see that E is proportional to 4.4 and it is in turn multiple of 11. Starting in the early 170s, concerns about the toxicity of PCBs have led to their banning in many countries.

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