Year 2024

Week # 2 Quiz 1

Q1. The inrush current in a transformer at no load is maximum if the supply voltage is switched on

Q2. In a 100 KVA transformer, the values of full load iron loss and copper loss are of the order of 900 W and 1600W respectively. At which KVA rating this transformer offers maximum efficiency?

Q3. When closed delta bank of transformer is converted into open delta connection, how much load will be supplied by each individual transformer with respect to the original load

Q4. The ratio of rotor input, rotor copper loss and rotor output is

Q5. Corresponding to certain load connected to a 6-pole, 50Hz wound rotor induction motor, frequency of currents in rotor circuit is observed as 90 cycles per minute. Estimate the rotor speed in rpm.

Q6. An alternator has 4-poles and 36 slots. In the winding, the coil span is taken 1-to-8 slot short pitched. Identify by how much degree, it is short pitched?

Q7. When the supply voltage to an induction motor is reduced by 10%, the maximum torque will decrease by approximately

Q8. Calculate core area of 500 kVA , 1-phase, 50 Hz, 6600/5000 V auto transformer, emf per turn = 8 V, maximum flux density 1.3 Wb/square meter

Q9. A 3 phase induction motor is running at slip S. If its two supply leads are interchanged, its slip at that instant is equal to

Q10. A three-phase 400 V, 6-pole, 50 Hz squirrel-cage induction motor is running at a slip of 5%. The speed of rotor with respect to stator magnetic field and speed of the stator magnetic field with respect to rotor magnetic field are