ELECTRICIAN 2nd YEAR MODULE – Alternator ONLINE TEST

Question 1 of 25

1. 7. What is the supply frequency of an alternator having 6 poles runs at 1000 rpm?

50 Hz

25 Hz

40 Hz

60 Hz

Question 1 of 25

Question 2 of 25

2. Here's the Aiken format for questions 1-11 with explanations:

Which formula is used to calculate EMF/phase in a ideal alternator?

E = 1.11 ᵩ FT

E = 4.44 ᵩ FT

E = 4.0 ᵩ FT

E = 2.22 ᵩ FT

Question 2 of 25

Question 3 of 25

3. 23. Calculate the pitch factor (KP) for a winding having 36 stator slots 4 pole with angle (α) is 30° in alternator.

0.978

0.942

0.985

0.965

Question 3 of 25

Question 4 of 25

4. 5. How alternators are rated?

KW

MW

KV

KVA

Question 4 of 25

Question 5 of 25

5. 15. What is the speed of an alternator connected with a supply frequency of 50 Hz at rated voltage having 4 poles?

4500 rpm

1000 rpm

1500 rpm

3000 rpm

Question 5 of 25

Question 6 of 25

6. 3. What is the name of the part of alternator?

Smooth cylindrical rotor

Salient pole rotor

Stator

Exciter

Question 6 of 25

Question 7 of 25

7. 24. What is the cause for hunting effect in alternators?

Due to over load

Due to continuous fluctuation in load

Running with fluctuation of speed

Running without load

Question 7 of 25

Question 8 of 25

8. 13. What is the purpose of damper winding in alternator?

Reduces windage losses

Reduces the copper loss

Improves the voltage regulation

Reduces the hunting effect

Question 8 of 25

Question 9 of 25

9. 10. How to compensate de-magnetizing effect due to armature reaction in an alternator?

Reducing field excitation current

Reducing the speed of alternator

Increasing field excitation current

Increasing the speed of alternator

Question 9 of 25

Question 10 of 25

10. 25. Calculate the voltage regulation in percentage if the load is removed from an alternator, the voltage rises from 480V to 660V.

32.5%

27.2%

37.5%

38.5%

Question 10 of 25

Question 11 of 25

11. 8. Calculate the speed of an alternator having 2 poles at a frequency of 50 Hz.

2500 rpm

6000 rpm

1500 rpm

3000 rpm

Question 11 of 25

Question 12 of 25

12. 4. What is the formula to calculate emf equation of an alternator?

E = 2.22 K_d K_c Fɸm

E = 1.11 K_d K_c F ɸm

E = 4.44 K_d K_c FT ɸm

E = 4.44 K_d K_c T ɸm

Question 12 of 25

Question 13 of 25

13. 17. What causes the terminal voltage of an alternator reduces, if the load increases?

Inductive reactance

Armature resistance

Field resistance

Armature reaction

Question 13 of 25

Question 14 of 25

14. 2. Which rule is used to find the direction of induced emf in an alternator?

Cork screw rule

Fleming's left hand rule

Right hand palm rule

Fleming's right hand rule

Question 14 of 25

Question 15 of 25

15. 22. What is the effect in increasing the field excitation current in alternator?

Alternator will be over loaded

Over voltage protection

Prevents demagnetizing

Dead short circuit protection

Question 15 of 25

Question 16 of 25

16. 12. What is the name of the equipment that provides D.C to the rotor of alternator?

Exciter

Synchroniser

Inverter

Converter

Question 16 of 25

Question 17 of 25

17. 18. What is the purpose of using damper winding in AC generator?

Reduces windage loss

Prevents heating

Reduces copper loss

Prevents the hunting effect

Question 17 of 25

Question 18 of 25

18. 11. What is the use of synchroscope?

Adjust the supply frequency

Adjust the output voltage

Indicate the correct instant for paralleling

Adjust the phase sequence

Question 18 of 25

Question 19 of 25

19. 9. What condition the lamps become dark in dark lamp method of parallel operation of two alternators?

Voltage and power rating are equal

Terminal voltages are equal

Frequency are same in both alternator

Voltage and frequency are equal

Question 19 of 25

Question 20 of 25

20. 19. What is the type of alternator?

Brushless alternator

Salient pole type alternator

Three phase alternator

Single phase alternator

Question 20 of 25

Question 21 of 25

21. 21. What is the advantage of using rotating field type alternator?

Easy to locate the faults in the field

Two slip rings only required irrespective of No. of phases

Easy to dissipate the heat during running

Easy to connect the load with alternator

Question 21 of 25

Question 22 of 25

22. 20. Calculate the speed in r.p.s of the 2 pole, 50Hz alternator?

50 rps

1500 rps

3000 rps

100 rps

Question 22 of 25

Question 23 of 25

23. 6. Which formula is used to calculate the percentage voltage regulation in alternator?

A

D

B

C

Question 23 of 25

Question 24 of 25

24. 14. Which condition is to be satisfied before parallel operation of alternators?

Stator impedance must be same

Rotor impedance must be same

Phase sequence must be same

Rating must be same

Question 24 of 25

Question 25 of 25

25. 16. What condition the two lamps become bright and one lamp dark during paralleling of two alternators?

Both the alternators receive same frequency

Voltages and phase sequence are equal

Voltages and frequencies are equal

Terminal voltages are equal

Question 25 of 25