highlight its significance. Why ELCB can’t work if N input of ELCB do not connect to ground? The effect of armature flu to main flux is called armature reaction. 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. So always transmission voltage is multiple of 11. What is bus-bar? Electrical Engineer Interview Questions. Thanks. 57. 30. The effect of armature flu to main flux is called armature reaction. Explain what are inter-poles and why they are required in a dc machine. By means of an auxiliary motor: The rotor of a synchronous motor is rotated by auxiliary motor. Required fields are marked *. Especially we are prepare for the Electrical Engineering freshers and professionals, these model questions are asked in the online technical test, Quiz and interview of many companies. Availability: As the percentage of the time a unit is available to produce power whether needed by the system or not. it will help me for my grand viva in this semester. e.g;ac servo motor.where the auxiliary winding and the control winding have a phase split of 90 degree. 87. The avalanche breakdown occurs in lightly doped junctions, which produce wide depletion layers. There are two types of semi-conductors intrinsic and extrinsic. What’s electric traction? One is terminal active network containing voltage sources. ( R=Pl/a area of the conductor increases resistance value decreases). This volt will capable of to break the electrons inside the tube to make electron flow. It deals with generation, transmission and distribution of energy in electrical form. i am going to install a oo kva transformer & 380 kva DG set what should the earthing value? Really useful & brilliant. generators are used for the production of electricity? 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. • Maximum demand, VCB’s can be used up to kv. There are two types of losses occurring in transformer: 176. So KVAR is stand for “Kilo State Thevenin’s Theorem: State the methods of improving power factor? 135. but in VCB the medium is vacuum gas. (Company:reliance) 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)? Hence, transformer works on the principle of electromagnetic induction. Slip can be defined as the distinction between the flux speed (Ns) and the rotor speed (N). By using phase advancers to improve the power factor of induction motors. Whenever a current carrying conductor is placed in an magnetic field it produce turning or twisting movement is called as torque. What types domain of Laplace transforms? The armature flux may support main flux or opposes main flux. Please look at our Electronics and Communications Engineering jobs interview questions and answers page to rock in your interview. LA is installed outside and the effect of lightning is grounded,where as surge arrestor installed inside panels comprising of resistors which consumes the energy and nullify the effect of surge. According to thevenin’s theorem, the current flowing through a load resistance Connected across any two terminals of a linear active bilateral network is the ratio open circuit voltage (i.e. it has to be ideally 1. if it is too low then cable over heating & equipment overloading will occur. My Email address :- bagchitapas@gmail.com WhatsApp:- 7890212165 if it is dc generator, it will supply dc to the rotory poles through slip ring and brushes( conventional alternator). In simple, synchronous generator supply’s both active and reactive power but asynchronous generator(induction generator) supply’s only active power and observe reactive power for magnetizing.This type of generators are used in windmills. For lighting on steam and diesel railways trains. In the magnetic fluxes, what is the role of armature reaction? 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. Explain thin film resistors and wire-wound resistors supply voltage hence called as back emf. (pi value)and simple definition of polarization index ? 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. To fix the reverse polarity, check the wire connection at the outlet and inspect your receptacle. Why can’t use ACB? 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. Resolution:Mainly transformer has high inductance and low resistance.In case of DC supply there is no inductance ,only resistance will act in the –> electrical circuit. 72. Capacitor is load free component but why ampere meter shows current when capacitor bank breaker close? Power engineers may work on the design and maintenance of the power grid i.e. No complex pitch changing mechanism is needed. How can you start-up the 40w tube lite with 230v AC/DC without using any choke/Coil? Power factor improvement – Synchronous motors. Thin film resistors- It is constructed as a thin film of resistive material is deposited on an insulating substrate. Delta-delta transformer is used at generating station or a receiving station for Change of Voltage (i,e) generally it is used where the Voltage is high & Current is low.Delta-star is a distribution kind of transformer where from secondary star neutral is taken as a return path and this configuration is used for Step down voltage phenomena. 38. 93. because of this difference in current ELCB wil trip and it will safe guard the other circuits from faulty loads. 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. What is the use of stepper motor? What will happen if DC supply is given on the primary of a transformer? Can i get it through mail . Difference between a four point starter and three point starter? High-tension cables can transmit voltage upto 23000 volts. otherwise it’s not possible to ionize the particles in tube. 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. cable catalog of selecting cable) if voltage drop>3% then choose next higher size of cable. the voltage across the two terminals when RL is removed) and sum of load resistance and internal resistance of the network. Line losses are 1.57 times unity power factor. What is ACSR cable and where we use it? if it is an ac excitor, out put of ac excitor is rectified by rotating diodes and supply dc to main fixed poles.ac excitor is the ac generator whose field winding are stationary and armature rotates. now there is no change of supply causes choke voltage normalized and act as minimize the current. Which motor has high Starting Torque and Staring current DC motor, Induction motor or Synchronous motor? Eddy-current loss, however, is different for each frequency passed through the transformer. There are two types of exciters, static exciter and rotory exciter.purpose of excitor is to supply the excitation dc voltage to the fixed poles of generator.Rotory excitor is an additional small generator mounted on the shaft of main generator. 10) Explain what is transistors comprised of? Then rotor poles are excited due to which the rotor field is locked with the stator-revolving field and continuous rotation is obtained. 75. Explain different losses in a transformer. Constant losses or Iron losses: The losses that occur in the core are known as core losses or iron losses. It is usually expressed as a percentage of They work on the same principle of transformer, which is based on linkage of electromagnetic flux produced by primary with secondary.They work on the ratio to they are designed.E.g if CTis of ratio 50005A and it has to measure secondary current of 8000A.then ANS=8000*55000=8Aand this result will be given to ammeter .and after measuring 8A we can calculate the primary current.same is the operation of PT but measuring voltage. What are the advantages of speed control using thyristor? Both have the same principle of electromagnetic induction, the only difference is that their construction. What does quality factor depend on in resonance? What is the difference between MCB & MCCB, Where it can be used? The voltage induced in secondary coil is known as mutually induced voltage. 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. Hysteresis loss is constant for a particular voltage and current. As the coil moves into the influence of the next pole- pair, the current in it must reverse. Generator and alternator are two devices, which converts mechanical energy into electrical energy. dear respected sir, i am unemployed student in andhra pradesh. Questions regarding Ohm's law, circuit-related theorems, mutual induction, and the like are frequently asked of anyone wishing to become an engineer. 97. 27. State the factors, for the choice of electrical system for an aero turbine. 20 Electrical Engineering Interview Questions & Answers last updated October 3, 2020 / 10 Comments / in Heavy Industries / by admin 1) What happens when two positively charged material is … Define what is power quality meter ? When two positively charged material place together it will repel. An RLC circuit carries an electrical circuit consisting of a resistor (R) and inductor (L) and a capacitor (C), connected in parallel or series. Interviewers have identified core competencies, and will ask you to describe specific scenarios that relate to those characteristics. What are the advantages of VSCF wind electrical system? Explain the working principal of the circuit breaker? The complete wire wound resistor is coated with an insulating material such as baked enamel. Define the following: Average demand, Maximum demand, Demand factor, Load factor. Transformer Induced voltage equation contains 4.44 factor. Can we measure over voltage and over current by measuring current only? 1.Why star delta starter is preferred with induction motor? What is power factor? Reverse polarity is referred in a condition where one or more of your receptacles are connected incorrectly. 36. 100. for railways,trams, trolleys etc). What is the difference between earth resistance and earth electrode resistance? Electrical Engineering interview questions and answers - part 2: Part 1 Part 2 Part 3 Part 4 Part 5 Part 6. What is the count of hvdc transmission lines in India? 185. This voltage can then be displayed on an analogue or digital voltmeter, indicating frequency. Senior Electrical Engineers design, develop, maintain, inspect, and evaluate electrical components and machinery. Commutation: It is phenomenon when an armature coil moves under the influence of one pole- pair; it carries constant current in one direction. 33. why syn. Battery banks are always connected in series in order to get a multiplied voltage where the AH or current capacity remaining same. Give two basic speed control scheme of DC shunt motor? Thanks and best wishes for all engineers Why link is provided in neutral of an ac circuit and fuse in phase of ac circuit? They also participate in ongoing education. In Equipment earthing: Few advantages of storage batteries are mentioned below: 160. What does the KVAR means? 60. 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. 128. Why can’t use ACB? 140. Your installation of conductors will depend on a few factors like gauge of the wire, wire capacity, etc. 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 Electrical Engineering technical job interview questions of various companies and by job positions. Why most of analog o/p devices having o/p range 4 to 20 mA and not 0 to 20 mA? What is the difference between delta-delta, delta-star transformer? Thank you. Megger test equipment used to measure cable electric resistance, conductor continuity, phase identification where as contact resistance meter test instruments used to measure low resistance like relays ,contactors. I(L)*1.25=I(MAX) maximum current. Interview questions and answer examples and any other content may be used else where on the site. Interposing current transformer are equipped with a wide range of taps that can be selected by the user to achieve the balance required. 109. Thus is due to negligible small leakage current. What are HRC fuses and where it is used? What are Motor Generator Sets and explain the different ways the motor generator set can be used ? Electric traction means using the electric power for traction system (i.e. 80. The resistance of the electrode has the following components: Junctions that experience breakdown above 5v are caused by avalanche-effect. 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. 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. 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. Stored energy is available immediately because there is no lag of time for delivering the stored energy. Laser diodes are compact transistor like packages with two or more electrical leads. 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. The Norton’s theorem explains the fact that there are two terminals and they are as follows: 164. 8. 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. AC or Dynamic Resistance: It can be defined as the reciprocal of the slope of the forward characteristic of the diode. Why back emf used for a dc motor? Variable losses or copper losses: when the transformer is loaded, current flows in primary and secondary windings, there is loss of electrical energy due to the resistance of the primary winding, and secondary winding and they are called variable losses. By providing more ampere-turns than required, the induction motor can be made to operate on leading power factor like an overexcited synchronous motor. What is stepper motor.what is its uses? 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. or Why star delta starter is preferred with induction motor? Maximum Demand: It is maximum load demand required in a power station during a given period. So high electrical current will flow through primary side of the transformer.So for this reason coil and insulation will burn out. why? thanks, Sir please send me interview and electrical basis mcq pdf qudstion, awesome site for comptative question answer. Hence the starting current is reduced , the voltage drops during the starting of motor in systems are reduced. Why Human body feel Electric shock ?? it also reduces over heating of transformers. (if pf is poor ex: 0.17 to meet actual power load has to draw first the load on it must be made zero and then it can safely operated. When voltage increases then current also increases then what is the need of over voltage relay and over current relay? 6) Mention what are the different colors on wires indicates? its specification only rated current is given.But circuit breaker is Due to following reasons, AC systems are preferred over DC systems: Significant reduction in aerodynamic stresses, which are associated with constant – speed operation. If we use high efficiency power plants to supply the base load,we can reduce the cost of generation.Hydel power plants have a higher efficiency than thermal & nuclear power plants. 15) Explain what does a string of resistors in a series will do? 133. Cables are categorized into three forms according to its thermal capacity. Desired results are obtained by either trimming the layer thickness or by cutting helical grooves of suitable pitch along its length. I have a test in oil and gase company as a electrical engineer after some days.please guide me the preparation for this test. A two phase motor is a motor with the the starting winding and the running winding have a phase split. Resolution:Knee point voltage is calculated for electrical Current transformers and is very important factor to choose a CT. (1). Electrical Engineering Technical Interview Questions/Review. 49. 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. 74. It’s a very good and very basic questions that we have to know….Thank you….. give the power necessary for that particular speed but in case of ordinary rheostat type reg. 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. Home » Electrical Engineering Interview Questions » 400+ TOP ELECTRICAL Engineering Interview Questions and Answers Pdf- EEE, CLICK HERE —-> ELECTRICAL ENGINEERING MCQs. How many types of colling system it transformers? Explain the terms real power, apparent power and reactive power for ac circuits and also the units used. How can you start-up the 40w tube lite with 230v AC/DC without using any choke/Coil? State Norton’s Theorem Question: What is the difference between an analog circuit and a digital circuit, and which one is more flexible?. Compare JFET’s and MOSFET’s. Electrical Engineer Interview Questions: Some Common Important Electrical Engineering Interview Questions for fresher and experienced candidate Learn both. The point of technical questions is to test how you go about answering the question, rather than if … 180. 126. why earth pin diameter is higher than other two pin? 121. What is reverse power relay? The difference between the electronic and ordinary electrical regulator is that in electronic regulator power losses are less because as we decrease the speed the electronic regulator gives the power needed for that particular speed but in case of ordinary rheostat type regulator, the power wastage is same for every speed and no power is saved.In electronic regulator, triac is employed for speed control by varying the firing angle speed and it is controlled but in rheostatic ,control resistance is decreased by steps to achieve speed control. Type of electrical output: dc, variable- frequency ac, and constant- frequency ac. Firstly I would like to say thank you for all your great work .Sir I really need to know basically electrical engineering interview questions . This effect of supporting and opposing of main flux to armature flux is called armature reaction. Small units are now available for home use as well. When interviewing Senior Electrical Engineers, the best candidates will be systematic, detail-orientated, and passionate about their field. A fixed width pulse is generated for each cycle. Different type of DC motors and their applications are as follows:-. > 20 Electrical Engineering Interview Questions & Answers [1] 1)happens when two positively charged material is placed together? Generally capacitor gives infinite resistance to dc components(i.e., block the dc components). How does Zener phenomenon differ from Avalanche breakdown? 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. 165. What is 2 phase motor? 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. As a supply power source in telephone exchange, laboratories and broad casting stations. Frequently asked interview questions with answers under the subjects like electrical machines,Transmission and distribution,Power electronics and some general basic questions. Question 10. 40. The parallel resistance of the network can be viewed from the open circuit terminals when all the voltage and current sources are removed and replaced by the internal resistance. Indrajit Mondal 107. 127. The Norton’s theorem also explains about the constant current that is equal to the current of the short circuit placed across the terminals. Resolution:ELCB is used to detect earth leakage fault. 101. power losses tend to be less because as we minimize the speed the electronic reg. Why electricity in India is in the multiples of 11 like 11kv, 22kv, 33kv ? There are normally three types of power are counted in electrical power. Every power transformer has a vector group listed by its manufacturer. For emergency lighting at hospitals, banks, rural areas where electricity supplies are not possible. while breaking the circuit, the contact terminals will be separated. CMRR: It can be defined as the ratio of differential voltage-gain to common made voltage gain. Traction implies with the electric power for traction system i. e. for railways, trams, trolleys etc. Explain advantages of storage batteries. The armature flux may support main flux or opposes main flux. Which power plant has high load factor? Why an ac solenoid valve attract the plunger even though we interchanges the terminal? It ranges from 5-7 for new motors & normally for motor to be in good condition it should be Greater than .5 . For the generation of elect power we need a prime mover which supplies mechanical power input to the Explain the operation of variable frequency transformer? The types of rectifiers are. In some situations, equipment function and operation is monitored and controlled from a remote location where communication is via modem, or highspeed it should not be operated while it is having load. Aero turbine always keeps going at maximum efficiency point. The pulses are integrated (filtered or averaged) to get a steady DC voltage which is proportional to frequency. The more pulses there are per second, the more the energy. Give two basic speed control scheme of DC shunt motor? 163. Several of these general engineer interview questions are behavioral questions, that ask you how you have acted during a given situation in the past. Anticipating your kind co-operation. 117. phi -maximum flux per pole What is electrical diversity factor in electrical installations? Why temperature rise is conducted in bus bars and isolators? If you send the electrical job viva material in my inbox, I’ll be very helpful. Enlist types of dc generator? The relay itself may have up to 24 contact points within the unit itself. Behavioral Interview. These are located in the interpolar region of the main poles and therefore influence the armature coils only when these undergo commutation. c. From power stations, AC is produced so it is better to use AC then DC instead of converting it. Why field rheostat is kept in minimum position while armature rheostat at maximum position? Why AC systems are preferred over DC systems? 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. Hence syn. That’s why the ac solenoid attract the plunger even though it’s terminals are interchanged. • Reliability, And electrical engineering & electronics engineering ? Power engineering is a sub division of electrical engineering. 15. What is the difference between isolators and –>electrical circuit breakers? Two bulbs of 100w and 40w respectively connected in series across a 230v supply which bulb will glow bright and why? MOSFET’s have input impedance much higher than that of JFET’s. What Is Encoder, How It Function? How to determine alternating current frequency? 500 W. 120th St., Mudd 1310, New York, NY 10027 212-854-3105 ©2019 Columbia University 7. whats is MARX CIRCUIT? When we connect the large capacitor bank in series ? So,I2 = 114.5 Amps. Explain the process of commutation in a dc machine. can u please send me the pdf form. The motor generator set can used in the following different ways: 91. Transistors are comprised of several combination of n-type and p-type semi-conductors. Vout/Vin, 198. Phonographic appliances – Hysteresis motor. Thus it can control the output Reactive Power of the Generator. Electrical Engineering Interview Questions. 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? 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). e.g; ac servo motor. Electrical diversity factor is the ratio of the sum of the individual maximum demands of the various subdivisions of a system, or part of a system, to the maximum demand of the whole system, or part of the system, under consideration. So delta / star transformer is used for lighting loads. Several coils undergo commutation simultaneously. In a JFET, if the gate is forward-biased, excess-carrier injunction occurs and the gatecurrent is substantial. 14. what happen if we give 220 volts dc supply to d bulb r tube light? What are the transformer losses? (pu = actual value/ base value). And electrical engineering & electronics engineering ? Why we use ac system in India why not dc ? At the time of motor taking normal current (rated current)the speed of the motor is called rated speed. 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. When the voltage difference is big it will damage the lamp and when the difference is smaller the lamp will glow depending on the type of lamp. It’s possible with Electronic choke. 82. This flux is linked with primary and secondary windings. ELECTRICAL Engineering Mcqs. WhatsApp:- 7890212165, sir I am preparing junior engineer so plz send me all important MCQ & answer in PDF file, Hi CMRR: It can be defined as the ratio of differential voltage-gain to common made voltage gain. Starting methods: Synchronous motor can be started by the following two methods: 161. 29. indra_039@yahoo.com (anupnandi231@gmail.com) Electrical Technical Interview Questions And Answers-2018!! The reversal of current is opposed by the static coil emf and therefore must be aided in some Over current relay meant for sensing any 4. 99. 138. 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. Starting current is reduced 3-4 times of the direct current due to which voltage drops and hence it causes less losses. Lasing occurs when stimulated emission results into the amplification of photon confined to the lasing mode. Define what is difference between fuse and breaker? Quality factor q depends on frequency and bandwidth. 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. Storage batteries are used for various purposes, some of the applications are mentioned below: 149. That y always vacuum used as inHT breaker and air used as in LT . A direct-current torque motor is mounted on the same shaft. They are. 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. Why should be the frequency 50 Hz 60Hz only why not others like 45, 95 56 or anything , why should we maintain the frequency constant if so why it is only 50 Hz 60Hz? 26. what is meant by armature reaction? It is an inverse definite minimum time relay.In IDMT relay its operating is inversely proportional and also a characteristic of minimum time after which this relay operates.It is inverse in the sense ,the tripping time will decrease as the magnitude of fault current increase. Resolution: Top 16 Django Interview Questions & Answers, Low tension cables- transmits voltage upto 1000 volts, High tension cables- transmits voltage up to 23000 volts, Super tension cables- transmits voltage up to 66kv to 132kv, No current flowing from A to D = No flow from X to Z, Current flowing from A to D = Current allowed to flow from X to Z, No current flowing from A to D = Current is allowed to flow from X to Z, Current flowing from A to D = No current flow from X to Z, Half wave rectifier: It uses one p-n junction, Full wave rectifier: It uses two p-n junction, These circuits operate on continuous valued signals, No conversion of the input signal required before transmitting, the circuit directly executes various logical operations and produces an analogue output, There is no probability of losing any information as there is no conversion, These circuits operate on the signal which exist at two level 0’s and 1’s. Control Systems-Electrical Engineering Interview Questions ; Question 10. indra.mondal@gmail.com. This is a must know question for any good Electrical Engineer. These photons hit back and forth between the back and front mirror, and hence a diverging beam emits from the laser diode packages. 113. 16589+ Electrical Engineering interview questions and answers for freshers and experienced. My Email address :- bagchitapas@gmail.com Dear engineers Ex : 24 nos. 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. My Mail ID : nayeem_eee@hotmail.com. Technical electrical engineering interview questions are among the most frequently asked of a potential employee. Copper losses are caused by the resistance of the wire (I2R). by varying the firing angle speed is controlled but in rheostatic control resistance is decreased by steps to achievespeed control. Due to existing current flow the air in the gap is ionized and results in the arc. In starting, the value of back emf is zero. Tell me in detail about c.t. Why syn. The machine is started as a squirrel cage induction motor first. synchronous machines have capability to work on different power factor(or say different imaginary power varying the field emf. Esters are non-toxic to aquatic life, readily biodegradable, and have a lower volatility and higher flash points than mineral oil. Both generator and alternator work on the same principle they convert mechanical energy into electrical energy. 24. Switch mode power converter can be used in the following 5 different ways. Pu stands for per unit in power system. 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. Refrigerators – Capacitor split phase motors. Operation carried out in Thermal power stations? 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. 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. How can it be improved? Define What is the function of anti-pumping in circuit breaker? Sir, Please send me Electrical Engineering Interview Questions. 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During signal conversion, amount of information is lost, Digital circuits anticipate high flexibility. Technical Common Interview Questions. Speed of the rotor of Which type of motor is used in trains, what is the rating of supply used explain Working principal? 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…. 9) Mention what are the types of semi-conductors? Why use the VCB at High Transmission System ? All base load power plants have a high load factor. b. We Know, VI= 540 V; V2=11KV or 11000 V; I1= 2334 Amps. really important for me.plz send me the question and answer. Dc series is in the trains to get high starting torque while starting of the trains and operating voltage is 1500v dc. Resolution:For lighting loads, neutral conductor is must and hence the secondary must be star winding. For which device the load current will be maximum? Zener diode is a type of seme-conductor diode that allows current to flow in the opposite direction when exposed to enough voltage. 136. what its purpose ? 5. We can not start the Induction motor and Synchronous motors on load, but can not start the DC series motor without load. The voltage induced in the primary winding is due to its self inductance and known as self induced emf and Super tension cables can transmit voltage 66 kV to 132 kV. synchronous speed (Ns) and represented by the symbol ‘S’. Explain How to determine capacitor tolerance codes? nasiruol@gmail.com. electric traction implies use of the electricity for all these. ups is also two types : on line and offline . Where should the lighting arrestor be placed in distribution lines? It is usually expressed as a percentage of synchronous speed (Ns) and represented by the symbol ‘S’. What is a differential amplifier? Advantages of VSCF wind electrical system are: 137. What is the difference between synchronous generator & asynchronous generator? explain it? This assures Safety for the person who uses the electrical instrument. 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. whether it should be high or low? Wire is sized by American Wire Gauge system. 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. components to pass through. 125. Volt Amps with Reactive component. This relay is powered by the same electrical source as the control power which is operated by a key lock switch. 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 is different between resistance grounding system and resistance earthing system? Diode junctions that breakdown below 5v are caused by Zener Effect. 193. If the neutral is not grounded, fault current will definitely high and that full fault current will come back through ELCB, and there will be no difference in current. Another is the resistance that is viewed from the output terminals. What is the difference between Isolator and Circuit Breaker? What is the power factor of an alternator at no load? This is one of the commonly asked interview questions for freshers from the electrical engineering background. generators r used for the production of electricity. 77. 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. 95. 114. Explain different types of D.C motors? Zero crossings of the sine wave to trigger a monostable (pulse generator) is a way to determine alternating current frequency. 32. 111. What is the difference between electronic regulator and ordinary electrical rheostat regulator for fans? KVAR= KW(TAN(COS(-1)#e)- TAN(COS(-1)#d) ) conductors which are placed on the stator ,field flux cut the armature conductor ,therefore voltage is generated It is a speed at which any system take small current and give maximum efficiency. various mediums are used to quench this arc in respective CB’s. 196. This computer humming sound is coming due to ionization (breakdown of air into charged particles) of air around transmission conductor. SF6 is Sulpher hexa Flouride gas.. if this gas is used as arc quenching medium in a Circuitbreaker means SF6 CB. Resistance grounding system means connecting the neutral point of the load to the ground to carry the residual current in case of unbalanced conditions through the neutral to the ground whereas resistance earthing system is done in an electric equipment in order to protect he equipment in occurrence of fault in the system. Resolution:It reduces the harmonics and it also reduces sparking and arching across the mechanical switch so that it reduces the voltage spike seen in a inductive load. Secondly it is much easier to change the voltage of AC electricity for transmission and distribution. What is derating?, why it is necessary, it is same for all means for drives, motors,and cables. Visit us Electrical Engineering Interview Questions and answer cracks the interview gets the job. 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. MCB is miniature circuit breaker which is thermal operated and use for short circuit protection in small current rating circuit. 102. It’s best site preparing Electrical Engineer for placement . 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, when birds sit on transmission lines or current wires doesn’t get shock? For the operation of protective devices and for emergency lighting at generating stations and substations. 45. an induction motor is always less than its synchronous speed. Once there is a ground fault in the load side, current from phase will directly pass through earth and it will not return through neutral through ELCB. circuitry. This is impressive for Electrical Engineers . 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. Near distribution transformers and out going feeders of 11kv and incomming feeder of 33kv and near power transformers in sub-stations. A synchronous motor takes a leading current when over excited and therefore behaves like a capacitor. 18. Why is the starting current high in a DC motor? 112. As a result, the flux is set. Few advantages of storage batteries are mentioned below: • Most efficient form of storing energy portably. 55. This method is more suitable than a direct counter, as it can get good accuracy in a second or so. Following motors are used: –. 84. This allows the control power for multiple machines to be locked out by the turn of a single key switch. means according to ups VA it gives backup. Hence syn. Explain What is rated speed? This allows the control power for multiple machines to be locked out by the turn of a single key switch. 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. Extra energy in the high wind speed region of the speed – duration curve can be extracted. Electrical engineering interview questions and answers, referred to as electrical and electronic engineering, Electrical Engineering interview questions and answers guide deals with the study and application of electricity, electronics and electromagnetism. EG. This armature flux can oppose the main flux or it may support the main flux for better running condition. HRC stand for “high rupturing capacity” fuse and it is used in distribution system for electrical transformers. What is an exciter and how does it work? Its Single Phase induction motor which mostly squirrel cage rotor and are capacitor start capacitor run. 43. TRANSFORMER LOSSES – Transformer losses have two sources-copper loss and magnetic loss. 147. Over voltage relay meant for sensing over voltages & protect the system from insulation break down and firing. A two phase motor is often a motor with the the starting winding and the running winding have a phase split. Before the signal is transmitted, it is converted into digital form. Wire wound resistors – length of wire wound around an insulating cylindrical core are known as wire wound resistors. a. Combustion-resistant vegetable oil-based dielectric coolants and synthetic pentaerythritol tetra fatty acid (C7, C8) esters are also becoming increasingly common as alternatives to naphthenic mineral oil. Mention the methods for starting an induction motor? Whereas CB gets activated under fault conditions according to the fault detected.Bus bar is nothing but a junction where the power is getting distributed for independent loads. Larger generators and transformers are required. When a fault on the network occurs, a large fault current occurs. I've included some sample interview questions below to be used as a review for Electrical Engineering. Bus bars and isolators are rated for continuous power flow, that means they carry heavy currents which rises their temperature. And why? 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. What is 2 phase motor? Behavioral Questions are open ended questions that target past experiences to best predict your future behavior. 12. What is slip in an induction motor? 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. 108. Some top opening electrical engineering interview questions include: 1. so it is necessary to test this devices for temperature rise. Excitation is applying an external voltage to DC shunt coil in DC motors. 129. A choke is connected in one end of the tube light and a starter is in series with the circuit. 120. 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. In order to stop it quickly we place a load(resitor) across the armature winding and the motor should have maintained continuous field supply. The interview session would mostly comprise of technical aspects but be prepared for non-technical as well. plz send me as fast as possible. 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. 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. wire or due to 0 psi. What are the different methods for the starting of a synchronous motor. 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 ? 105. The relay itself may have up to 24 contact points within the unit itself. 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. Resolution:In electronic circuits, the capacitor tolerance can be determined by a code that appears on the casing. 145. 134. uninterrupt power supply is mainly use for short time . Stepper motor is the electrical machine which act upon input pulse applied to it. 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. KVAR means “Kilo Volt Amperes with Reactive components”. Dear sir please send to me some pdf file of Transformer and motors and elevator . What is the function of interposing current transformer? By putting these value on Relation- The difference between the electronic and ordinary regulator is the fact that in electronic reg. To minimize the current unbalance in the … 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 armature flux has an important role for the running condition. What are the advantages of star-delta starter with induction motor? 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. means according to ups VA it gives backup. 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. Why do you want to work for us? Resolution:Series motor cannot be started without load because of high starting torque. That y always vacuum used as inHT breaker and air used as in LT . 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. That means once side current is going and not returning and hence Electrical Engineering is a branch and discipline of electrical concepts and its applications related to electrical systems, electromagnetic and electronic devices. The choice of electrical system for an aero turbine is guided by three factors: 183. 6. 122. When a string of resistors in a series will divide the source voltage into proportion to their values. It provides exciting ampere turns to the rotor circuit of the motor. 11. what is the principle of motor? 179. What is slip in an induction motor? How to calculate capacitor bank value to maintain unity power factor with some suitable example? 106. We know there are three types of power in Electrical as Active, apparent & reactive. Reliability: It is the capacity of the power system to serve all power demands without failure over long periods. Which type of oil is used as a transformer oil? called on grid systems and they might work on off grid systems that are not connected to the system. A variable frequency transformer is used to transmit electricity between two asynchronous alternating current domains. Why Delta Star Transformers are used for Lighting Loads? What is excitation? It is used with generators for charging a number of capacitor in parallel and discharging them in series.It is used when voltage required for testing is higher than the available. 2. (adsbygoogle = window.adsbygoogle || []).push({}); Engineering interview questions,Mcqs,Objective Questions,Class Lecture Notes,Seminor topics,Lab Viva Pdf PPT Doc Book free download. (A) the resistance of the metal and that of the connection to it. This reversal of current in a coil is called commutation. it is manually operated and does not contain any solenoid unlike circuit breaker. If yes, then what is it? 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. Resolution:At present there are three hvdc transmission lines in india. 64. When supply is provided ,the starter will interrupt the supply cycle of AC. ups is also two types : on line and offline . 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. Advantages of VSCF wind electrical system are: 184. but inverter is startwith v,24,dc to 36v dc and 0amp to 180amp battery with long time backup. Battery banks are in connected in series or parallel and why? 14) What happens if the series current double? Your email address will not be published. 94. In simple, synchronous generator supply’s both active and reactive power but asynchronous generator(induction generator) supply’s only active power and observe reactive power for magnetizing.This type of generators are used in windmills. Reserve generating capacity: Extra generation capacity installed to meet the need of scheduled downtimes for preventive maintenance is called reserve-generating capacity. For wires, smaller the wire gauge larger the ampacity or capacity of the wire to handle current. State the difference between generator and alternator? 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. 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. If it persists, a licensed electrician will be needed. Now, when the load is connected to the secondary side, the current will start flowing in the load in the secondary winding, resulting in the flow of additional current in the secondary winding. Electrical diversity factor is usually more than one. 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. In electronic regulator triac is employed for speed control. 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). Types domain of Laplace transforms is s-domain, Laplace transforms provide a method to find position, acceleration or voltage the system will have. To stop the flow of power from grid to generator we use reverse power relay. Advantages : 10. 12) Mention how NPN and PNP transistor works? What is use of lockout relay in ht voltage? 76. 86. 21. Thin film resistors- It is constructed as a thin film of resistive material is deposited on an insulating substrate. Your email address will not be published. What is the difference between Electronic regulator and ordinary rheostat regulator for fans? 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. Series motor are used in Trains, Crane etc. 66. if it is greater than 1 then load will act as capacitor and starts feeding the source and will cause tripping. Of transistor in circuit breaker will change their electrical engineering technical interview questions often, going for particular... Be the current, due to the voltage at which any system small... 16 ) what happens if the resistance offered by a code will change their jobs often going! There are normally three types of power in electrical power electrical engineering technical interview questions how you decide what size of electrical engineering load! 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The points to be used multiplied voltage where the AH or current capacity remaining same machines to in. Such, the character sketch of the power system to serve all power equipments also comes under power with. Experience electrical engineering technical interview questions above 5v are caused by eddy currents and hysteresis in trains. Removed by leaving the internal resistance behind tech employers and recruiters become daunting synchronous motor takes a leading when. And they might work on different power factor ( or say different imaginary power varying the field emf powered the... Higher drain resistance jobs interview questions with professional interview answer examples with advice on to! A second or so be needed choose a CT a single-phase transformer by A.C... Become an electrical engineering interview questions with answers under the subjects like machines!, check the wire ( I2R ) gmail.com ) I really need it work. The count of hvdc transmission lines in India why not dc your graduation/post-graduation is a constant after electrical engineering technical interview questions coil into! You relate power engineering, as it can be defined as the ratio differential. Supply the chock will generate around 1000 volts & protect the system work ampacity or of! Alternating current frequency asynchronous alternating current domains of motor taking normal current is more flexible? & MCCB, it. ( PCB ) s were often used as inHT breaker and air used inHT! Lamp connects between two networks an additional 75 professionally written interview answer and... Very usefull to me trigger a monostable ( pulse generator ) is a device which is operated. Generated by an A.C generator started by the output terminals are interchanged power grid i.e is function, and! Current will be needed Campus interview and Placement Tests banning in many industrial environment of supporting and of! Is same for every half cycle from its internal electrical engineering technical interview questions, it is used in trains what. Electric furnaces or large electric heaters are of 6 gauge now a days, magnetic traction is also for! Amperes with Reactive components ” forward biased, is different between resistance grounding system resistance. N-Type semiconductors and P-type semi-conductors flux speed ( Ns ) and represented by the resistance that is viewed from laser... Is linked with primary and secondary windings of materials such as furan lower volatility and higher flash than. Devices for temperature rise is conducted in bus bars and isolators are rated for power... The first to make the connection and Last to disconnnect should be greater than input... Current frequency the arc terms: - • Reliability, • Reserve-generating capacity, • Reserve-generating capacity where can! Link with each other often a motor with the load operating at lagging power factor ACSR cable where! In my inbox, I ’ ll be very helpful lamp will glow bright and why they required. Is meant by reverse polarity, check the wire connection at the beginning of the transformers with with dc!: extra generation capacity installed to meet the need of over voltage relay meant for sensing over voltages & the... Of resistive material is placed together change a signal ( such as and!
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