Year 2024

Week # 2 Quiz 1

Q1. A long shunt DC compound generator delivers 110 KW at 220 volts. If \(R_a = 0.01\) ohms, \(R_{se} = 0.002\) ohms and shunt field resistance is of 110 ohms, calculate the value of induced EMF. (consider up to one decimal place)

Q2. Calculate % voltage drop of transformer with a % resistance of 2.5 ohm and % reactance of 5 ohm of rating 500 kVA when it is delivering 400 kVA at 0.8 power factor lagging

Q3. A 3-phase transformer of 220/11000 line volts is connected in star/delta with differential protection system. The protective transformers on 220 V side have a current ratio of 500/5. What should be the CT ratio on 11000 V side? Assume that the line current on 220 V side is 300 A.

Q4. In a single phase induction motor, the relationship between the slip of the rotor with respect to the forward rotating field \(S_f\) and backward rotating field \(S_b\) is

Q5. A 400V/100V , 20KVA two winding transformer is reconnected as an autotransformer, the maximum rating of that autotransformer is

Q6. An alternator is supplying a load of 500 kW at a p.f of 0.5 lagging. If the power factor is raised to unity, how many more kW can alternator supply for the same kVA loading?

Q7. A 4-pole, \(500\: V\) DC shunt motor has 720 wave connected conductor on its armature. The full load armature current is \(60\: A\) and the flux per pole is \(0.03\: Wb\), the armature resistance including brush contact is \(0.2\: \Omega\). Calculate the full load speed of the motor.

Q8. Determine the optimum value of load resistance for maximum power transfer if the load is connected to an amplifier of output resistance 150 Ω through a transformer with a ratio of number of turns in the primary winding to the number of turns in the secondary winding is equal to 5.

Q9. A DC shunt generator having \(R_{sh}\: =\:50\Omega\) was generating normally at 1000 rpm. The critical resistance of machine was \(80\Omega\). Due to some reason the speed of the prime mover become such that generator fails to generate. The speed at that time must have been

Q10. In a DC series motor, the torque developed is 20 Nm at 10 A load current, if the load current is doubled, the new torque will be