1. Consider the followingstatements: The diodes in avoltage source inverter (McMurry inverter) should be ableto 1. withstand a large voltagein the reverse direction 2.carry the cumutating currentexcess of load current 3.provide the required reversebias to the outgoing thyristor4. feedback the reactivecurrent to the source Of thesestatements:

2. In a single-phase powerfactor meter - the controllingtorque is

3. A 4-point starter is usedto start and control the speedof a

4. In a synchronousgenerator operating at zeropower factor lagging - the effectof armature reaction is

5. Keeping in view the costand overall effectiveness - thefollowing circuit breaker isbest suited for capacitor bankswitching

6. Consider the followingstatements about SCR1. For normal SCRs. turn-ontime is more than turn-offtime.2. a forward voltage can beapplied to on SCR after itsgate recovery time.3. Static V-I characteristics ofan SCR with different gatedrives applied to the gate areindicated by Vgl > Vgl > VgoWhich of the following iscorrect?

7. To increase the visualsynchronous motor connectedto ac mains is running at fullload and unity power factor. Ifits shaft load is reduced byhalf - with field current heldcritical voltage of corona foran overhead line - one solidphase-conductor is replacedby a -œbundle- of four smallerconductors per phase - havingan aggregate cross-sectionalarea equal to that of the solidconductor. If the radius of thesolid conductor is 40 mm - then the radius of each of thebundle conductors would be

8. One Kilowatt hour ofelectrical energy is the sameas105

9. The discrete time systemdescribed by y(n) = x2(n) is

10. A C.R.O. is operated withX and Y settings of 0.5mV/cm and 100 mV/cm. Thescreen of the C.R.O. is 10 cm× 8 cm (X and Y). A sine waveof frequency 200 Hz andr.m.s. amplitude of 300 mV isapplied to the Y-input. Thescreen will show

11. A 4-bit ripple counter anda 4-bit synchronous counterare made using flip flopshaving a propagation delay of10 ns each. If the worst casedelay in the ripple counterand the synchronous counterbe R and S respectively - then

12. The speed of a 4-poleinduction motor is controlledby varying the supplyfrequency while maintainingthe ratio of supply voltage tosupply frequency (V/f)constant. At rated frequencyof 50 Hz and rated voltage of400V its speed is 1440 rpm.Find the speed at 30 Hz - if theload torque is constant.

13. In a conventional reverseblocking thyristor

14. A certain oscilloscopewith 4 cm × 4 cm screen hasits own sweep output fed to itsinput. If the x and ysensitivities are same - theoscilloscope will display a

15. Skewing of the rotor in athree-phase squirrel-cageinduction motor reduces

16. Generally the no-loadlosses of an electrical machineis represented in itsequivalent circuit by a

17. Consider the followingstatements: (i) Thecompensating coil of a lowpower factor wattmetercompensates the effect of theimpedance of the current coil.(ii) The compensating coil of alow power factor wattmetercompensates the effect of theimpedance of the voltage coilcircuit.

18. Consider the followingstatements about SCR1. For normal SCRs. turn-ontime is more than turn-offtime.2. a forward voltage can beapplied to on SCR after itsgate recovery time.3. Static V-I characteristics ofan SCR with different gatedrives applied to the gate areindicated by Vgl > Vgl > VgoWhich of the following iscorrect?

19. If the field of a dc shuntmotor gets opened while themotor is running - then the

20. The full-load copper-lossapplicable to only:and iron-loss of a transformerare 6400 W and 5000 Wrespectively. The copper-lossand ironloss at half load willbe - respectively

21. A chopper operating at afixed frequency is feeding anR-L load. As - the duty ratio ofthe chopper is increased from25°h to 75°h - the ripple in theload current

22. A synchronous generatoris feeding a zero power factor(lagging) load at rated current.The armature reaction is

23. Electric flux at a point inan electric field is

24. Consider the followingstatements related to a CMOS(Complementary metal oxidesemiconductor) inverter:1. It combines an n-channeland a p-channel MOStransistor.2. For binary 1 input - bothtransistors are OFF.3. For binary 0 input - bothtransistors are ON.4. Whatever is the state ofinput - one transistor is ONwhile the other is OFF. Whichof the statements given aboveare correct?

25. Consider the followingstatements about SCR1. For normal SCRs. turn-ontime is more than turn-offtime.2. a forward voltage can beapplied to on SCR after itsgate recovery time.3. Static V-I characteristics ofan SCR with different gatedrives applied to the gate areindicated by Vgl > Vgl > VgoWhich of the following iscorrect?