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Home⇒ Engineering⇒
Alternators
1-Dont try to cram or spend more time here just read it fast and cover syllabus then practice MCQ's cheptor of same topic to check your progress. . |
2-Wrong options are also given but dont concentrate there, Right answer is in bold format. |
Q21 ⇒ Damper winding on alternator results
in all of the following except increases instability of machine [other wrong options] [Discuss in forum] elimination of harmonic effects absorption of energy of oscillations when operating in parallel with other alternators suppression of spontaneous hunting- when supplying power to transimission line with high resistance to reactance ratio |
Q22 ⇒ Alternators, now a days, are designed
to have poor regulation because it limits the value of short circuit current [other wrong options] [Discuss in forum] it reduces the construction cost we employ automatic voltage regulators none of the above |
Q23 ⇒ If the input to the primemover of an
alternator is kept constant but the excitation
is increased, then kVA will be lagging [other wrong options] [Discuss in forum] kVA will be leading kW will be changed the power factor of the load remains constant |
Q24 ⇒ A commercial alternator has stationary armature and rotary field [other wrong options] [Discuss in forum] rotating armature and stationary
field both armature and field rotary both armature and field fixed |
Q25 ⇒ Dirt accumulation in generators can
cause all of the above [other wrong options] [Discuss in forum] flashovers overheating poor voltage regulation |
Q26 ⇒ The maximum current that can be supplied
by an alternator depends on speed of the exciter [other wrong options] [Discuss in forum] exciter current strength of the magnetic field number of poles |
Q27 ⇒ Synchronous impedance method of
finding voltage regulation of an alternator
is called pessimistic method because it gives regulation value higher than is actually found by direct loading [other wrong options] [Discuss in forum] it is simplest to perform and compute armature reaction is wholly magnetising none of the above |
Q28 ⇒ The Poter's triangle separates the armature leakage reactance and armature reaction m.m.f. [other wrong options] [Discuss in forum] stator voltage and rotor voltage field m.m.f. and armature m.m.f. iron losses and copper losses |
Q29 ⇒ In an alternator the voltage of field
system is usually less than 200 V [other wrong options] [Discuss in forum] more than 1000V between 400 V and 600 V none of the above |
Q30 ⇒ A lower voltage alternator, for the same
power rating, will be larger in size [other wrong options] [Discuss in forum] more costly more efficient operating at high r.p.m. |
Q31 ⇒ Which of the following relays come into
operation in the event of the failure of
prime-mover connected to the generator
? Reverse power relay [other wrong options] [Discuss in forum] Buchholz relay Differential relay All of the above None of the above |
Q32 ⇒ Which of the following organisations is
engaged in the manufacture of large size
alternators for power plants in India ? Bharat Heavy-Electricals Ltd. [other wrong options] [Discuss in forum] Department of Science and
Technology Electricity Authority of India National Thermal Power Corporation Ltd. |
Q33 ⇒ Which of the following primemover is
least efficient ? Steam engine [other wrong options] [Discuss in forum] Gas turbine Petrol engine Diesel engine |
Q34 ⇒ Modern 3-phase alternator of a central
power station will have generated voltage
of 11 kV [other wrong options] [Discuss in forum] 132 kV 400 V 230 V |
Q35 ⇒ Fleming's left hand rule may be applied
to an electric generator to find out
direction of induced e.m.f. [other wrong options] [Discuss in forum] magnetic field rotor rotation none of the above |
Q36 ⇒ In an alternator, for a coil having a
span of 2/3 of pole pitch, the coil spanfactor
will be 0.866 [other wrong options] [Discuss in forum] 0.707 0.6 0.2 |
Q37 ⇒ In a cylindrical rotor how much portion
of the rotor is wound ? Two third [other wrong options] [Discuss in forum] One third Half Full |
Q38 ⇒ Voltage regulation of an alternator is
usually much higher than that of a power transformer [other wrong options] [Discuss in forum] equal to that of power transformer much lower than that of a power transformer |
Q39 ⇒ Generated e.rn.f. for same field current
and double speed will be double [other wrong options] [Discuss in forum] same less than double more than double |
Q40 ⇒ For the alternators operating in parallel,
if the load shared by one of them is
to be increased, its field excitation is to be kept constant but input torque should be increased [other wrong options] [Discuss in forum] to be weakened keeping input
torque same to be strengthened keeping input torque same to be kept constant but input torque should be decreased |
Or |