electrician

MCQ ON ALTERNATOR PAGE - 2

1.
 Which type of alternator is used in hydroelectric power stations? A Non-salient pole alternator B Turbogenerator C Salient pole alternator D Steam turbine alternator Answer : C Explanation :
2.
 The armature reaction effect in a synchronous machine depends on A Load current B Power factor of the load C Speed of the machine D Both A and B Answer : D Explanation :
3.
 Skew of rotor bar eliminates A The effect of space harmonics B The entire effect of crawling C Magnetic noise D Variation due to unequal force developed on rotor Answer : A Explanation :
4.
 The alternators are rated as A kW B kVAR C kVA D kWh Answer : C Explanation :
5.
 The generated frequency in India is …. A F=65Hz B F=60Hz C F=55Hz D F=50Hz Answer : D Explanation :
6.
 The relation between frequency speed and number of poles in Alternator is given as … A
7.
 A 10 Pole alternator rotates at a constant speed of 1200 rpm. The periodic time of voltage in seconds per cycle will be A 0.01 B 0.02 C 0.04 D 0.08 Answer : A Explanation :
8.
 The field circuit of an alternator is supplied with A An oscillating current B A direct current C An alternating current D A pulsating current Answer : B Explanation :
9.
 The D.C and A.C generators are similar in one important function. That is the … A Generated  emf is a direct current B Generated emf is an alternating current C Generated emf is a pulsating current D Generated emf is an oscillating current Answer : B Explanation :
10.
 Adjusting the speed of the prime mover of an alternator is primarily necessary. Which one of the following is the reason for this? A To get constant frequency B To get constant voltage C To get increase polarity D None of the above Answer : A Explanation :
11.
 Which one of the following is the reason for using dampers in large alternator work? A To increase stability B To increase output C To decrease output D To reduce voltage fluctuation Answer : A Explanation :
12.
 The speed of a 6 pole 50 Hz of an alternator is A 1800 rpm B 1200 rpm C 1000rpm D 600rpm Answer : C Explanation :
13.
 The RMS value of emf induced per phase in alternator is given as… (assuming Kd and Kc are constant) A a B b C c D d Answer : Select Correct Ans Explanation :
14.
 A large diameter of alternator is running at slow speed will be having … A Rotating alternator B Rotating field with a smooth cylindrical rotor C Rotating field with a salient pole rotor D Rotating armature with field Answer : C Explanation :
15.
 A 3-phase star connected alternator having a rotating armature will have… A 2 slip rings B 3 slip rings C 4 slip rings D 6 slip rings Answer : C Explanation :
16.
 A 3-phase, delta connected alternator having a rotating armature will have… A 2 slips rings B 3 slips rings C 4 slips rings D 6 slips rings Answer : B Explanation :
17.
 A 3-phase, star connected alternator having a rotating armature will have 4 slip rings but 3 phase, delta connected alternator having armature will have A 6 slip rings B 4 slip rings C 3 slip rings D 2 slip rings Answer : C Explanation :
18.
 In star connected alternator. If the line voltage is  What will be the p A B C D Answer : D Explanation :
19.
 When all dark lamp method is used for synchronizing two 3-phase alternators, the lamps are not becoming dark at the same time but occurs at different timings. Bulbs used are of same wattage and vol A Frequency B Speed C Phase sequence D Voltage Answer : C Explanation :