K.K.WAGH POLYTECHNIC, NASHIK-03 Electrical Engineering Department. . Subject:- Electrical Engineering. Sub. Code: - (17404). Class:-SYME. SEM:-Fourth Sub. Abv.-EEN Course:-ME-4G. Question Bank Chapter 1. 1. 2. 3. 4. Write the stages of electrical power supply system. Write difference between AC & DC supply. Explain meaning of: a) Generation of electricity b) Transmission of electricity. Find the current drawn by 100Ω resistive load when it is connected across 230 V,50 Hz A.C supply. 5. A 60 Hz voltage of 115V is supplied to 100Ω resistance. Write time equation of voltage and current. 6. Find the current taken by a 100µf capacitor when it is connected across 230V,50Hz supply. 7. Define r.m.s. value of A.C quantity. 8. Draw circuit diagram and with the help of waveform and phasor diagram comment on the phase relationship between voltages and current in R-L series circuit and RCseries circuit. 9. Define inductive and capacitive reactance. 10. Define the following terms related to A.C circuit : a)waveform b)instantaneous value c)cycle d)time period. 11. An Alternating voltage is represented by the following expression:- V=25sin(200πt). Calculate the following:- 1.Amplitude 2.Time Period(T) 3.Frequency. 4.Angular velocity 5.Form factor 6. Crest Factor. 12. A coil of resistance 20Ω and inductance 0.05H is connected in series with capacitor 50µf. A source voltage of 230V 50Hz is connected across series connection. Calculate the following: a)current drawn from circuit b) phase difference between phase voltage and current. c)voltage drop across coil and capacitor . 13. A balance star connected load is supplied from 400V,3φ,50Hzsupply.the resistance per phase is 25Ω Calculate: a)line voltage b)phase voltage c)line current d)power consumed . 14. Compare star connected load with delta connected load. 15. State advantages of polyphase system over single phase system. 16. State the different types of power and their expression for a 3φ AC system. 17. Given the expression of Line values and Phase values for Star connected supply? 18. Given the expression of Line values and Phase values for Delta connected supply? Chapter 2 1. 2. 3. 4. 5. 6. 7. 8. 9. Define the following: a) Deflecting torque b) Controlling torque c) Damping torque. How to extend the range of a voltmeter & ammeter? Explain the construction and principle of operation of dynamometer type instrument. State the advantages and disadvantages of dynamometer type instrument. What do you understand by underdamped, critically damped and overdamped instrument? Name the meters used for measuring: a)DC voltage b)AC voltage. Explain three torques required for indicating meters. Write working principle of PMMC type meters. Draw neat laballed diagram of attraction type moving iron instrument. Chapter 3 1. State the working principle of DC motor and Fleming’s left hand rule. 2. Draw the Speed-Torque characteristic of D.C. series and D.C. shunt motor. 3. A 6 pole, lap wound shunt motor has 500 conductors in the armature. Find the speed of the motor when it takes 120A from dc main of 100 volts supply. The resistance of the armature is 0.05Ω and shunt field resistance is 25 Ω. The flux per pole is 20 mWb. 4. State the necessity of starter for d.c. shunt motor. 5. Draw the schematic diagram of dc series and dc shunt motor and mark voltage, currents and back e.m.f. 6. List the main parts of DC machine. Write the function of any four. 7. Why dc series motor is never started on no load? Explain. Chapter 4 1. Derive the emf equation of a transformer. 2. A single phase 50hz 230/115 volts drawa a primery current of 4 amp at full load.Find 1. KVA rating of transformer 2.Secondary full load current 3. A 50 kVA, 6600/250V transformer has 52 secondary turns, calculate: 1.Primary turns 2.Primary current 4. With simple diagram show where you will measure primary voltage and current as well as secondary voltage and current in 1 φ transformer. 5. Compare autotransformer with two winding transformer. Write two applications of auto transformer. Chapter 5 1. Compare A.C. and D.C. motor on the basis of: 1.Supply 2.Speed control3.Maintenance 4.Applications 2. A 3-phase, 4-pole, 50 HZ induction motor works with a full load slip of 3%. Find: 1. Synchronous speed2.Actual speed of motor 3. Explain star-delta starters used for 3-φ induction motor. 4. Name the single phase motor used for following applications: 1.Electric Mixer 2.Celling Fan 3.Toys 4.Compressors 5. Draw the schematic diagram of capacitor start single phase induction motor.Explain its working with the help of phasor diagram. 6. Draw and explain shaded pole induction motor with sketch. 7. Write the principle of operation of an alternator. 8. Explain the construction of alternator with neat diagram. 9. List any four advantages of having stationary armature and a rotating field construction in case of 3 phase alternator. 10. Explain why synchronous motor is not self starting? 11. Explain construction, working and application of synchronous motor. Chapter 6 1. 2. 3. 4. 5. 6. 7. 8. Write the classification of electric drives. Write eight advantages of electrical drives. What are the different types of encloseres for electrical motor? Explain electrical welding with neat diagram. Explain the dielectric heating with neat sketch and wire its applications. Explain resistance and induction heating. Name two electrical machines used in electro-agro system. Explain the process of electroplating used in electrometallurgical system. Chapter 7 1. Give any two advantages of MCCB? 2. Draw simple electrical wiring diagram for the control of one lamp, one wall socket and one fan,along with location of supply and fuse. 3. Write the fullform of MCCB &ELCB. Explain their working and write their applications. 4. Write diffrent types of lamps.explain any one lamp used for domestic purpose. 5. State any four methods of power factor improvement. 6. What is the function of fuse? 7. Write types of tariff? 8. Name the methods used to improve powerfactor 9. Draw neat wiring diagram of control 2 socket,2 fans & 2 lamps. 10. What is necessity of earthing ?