ELECTRICIAN 2nd YEAR MODULE – Alternator ONLINE TEST

Question 1 of 25

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

Alternator will be over loaded

Over voltage protection

Dead short circuit protection

Prevents demagnetizing

Question 1 of 25

Question 2 of 25

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

E = 4.44 K_d K_c T ɸm

E = 1.11 K_d K_c F ɸm

E = 2.22 K_d K_c Fɸm

E = 4.44 K_d K_c FT ɸm

Question 2 of 25

Question 3 of 25

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

60 Hz

40 Hz

25 Hz

50 Hz

Question 3 of 25

Question 4 of 25

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

4500 rpm

3000 rpm

1500 rpm

1000 rpm

Question 4 of 25

Question 5 of 25

5. 19. What is the type of alternator?

Three phase alternator

Salient pole type alternator

Single phase alternator

Brushless alternator

Question 5 of 25

Question 6 of 25

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

100 rps

3000 rps

50 rps

1500 rps

Question 6 of 25

Question 7 of 25

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

Prevents heating

Reduces copper loss

Reduces windage loss

Prevents the hunting effect

Question 7 of 25

Question 8 of 25

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

Voltages and frequencies are equal

Voltages and phase sequence are equal

Terminal voltages are equal

Both the alternators receive same frequency

Question 8 of 25

Question 9 of 25

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

Right hand palm rule

Cork screw rule

Fleming's right hand rule

Fleming's left hand rule

Question 9 of 25

Question 10 of 25

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

Easy to connect the load with alternator

Easy to dissipate the heat during running

Two slip rings only required irrespective of No. of phases

Easy to locate the faults in the field

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.

1500 rpm

3000 rpm

6000 rpm

2500 rpm

Question 11 of 25

Question 12 of 25

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

Improves the voltage regulation

Reduces the hunting effect

Reduces windage losses

Reduces the copper loss

Question 12 of 25

Question 13 of 25

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

0.985

0.942

0.965

0.978

Question 13 of 25

Question 14 of 25

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

Frequency are same in both alternator

Voltage and power rating are equal

Terminal voltages are equal

Voltage and frequency are equal

Question 14 of 25

Question 15 of 25

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

A

D

C

B

Question 15 of 25

Question 16 of 25

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

Rating must be same

Rotor impedance must be same

Phase sequence must be same

Stator impedance must be same

Question 16 of 25

Question 17 of 25

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

Inductive reactance

Field resistance

Armature resistance

Armature reaction

Question 17 of 25

Question 18 of 25

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

Due to continuous fluctuation in load

Running with fluctuation of speed

Due to over load

Running without load

Question 18 of 25

Question 19 of 25

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

Converter

Synchroniser

Exciter

Inverter

Question 19 of 25

Question 20 of 25

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

Salient pole rotor

Stator

Exciter

Smooth cylindrical rotor

Question 20 of 25

Question 21 of 25

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

Reducing field excitation current

Increasing the speed of alternator

Reducing the speed of alternator

Increasing field excitation current

Question 21 of 25

Question 22 of 25

22. 11. What is the use of synchroscope?

Adjust the supply frequency

Adjust the phase sequence

Adjust the output voltage

Indicate the correct instant for paralleling

Question 22 of 25

Question 23 of 25

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

E = 1.11 ᵩ FT

E = 4.0 ᵩ FT

E = 2.22 ᵩ FT

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

E = 4.44 ᵩ FT

Question 23 of 25

Question 24 of 25

24. 5. How alternators are rated?

MW

KW

KVA

KV

Question 24 of 25

Question 25 of 25

25. 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 25 of 25