A Best Way To Crack Gorenment Job Exams

Electrical Engineering Objective Questions { Alternators }

134. Salient pole type rotors as compared to cylindrical pole type are
A. small in diameter as well as axial length
B. large in diameter as well as axial
C. smaller in diameter and larger in axial length
D. larger in diameter and smaller in axial length
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135. Which of the following relays come into operation in the event of the failure of prime-mover connected to the generator?
A. Buchholz relay
B. Reverse power relay
C. Differential relay
D. All of the above
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136. The per unlit vuaages of two synchronous machines connected through a lossless line are 0.95 L10? and 1.0 LO?. Match the two sides in the following
A. Real power of (P) Positive real power Machine
B. Reactive power of (Q) Positive reactive Machine power
C. Power factor of (R) Negative real Machine 1 power (S) Negative reactive power (T) Leading power factor (U) Lagging power factor
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137. A 100 MVA, 11 kV, 3-phase, 50 Hz, 8-pole synchronous generator has an inertia constant H equal to 4 seconds. The stored energy in the rotor of the generator at synchronous speed will be H= ?
A. 100 MJ
B. 400 MJ
C. 800 MJ
D. 12.5 MJ
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138. A synchronous generator connected to an infinite bus is overexcited. Considering only the reactive powe, from the point of view of the system, the machine acts as
A. capacitor
B. an inductor
C. a resistor
D. none of the above
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139.  The neutral of 10 MVA, 11 KV alternator is earthed through a resistance of 5 ohms. The earth =fault relay is set to loperate at 0.75 A. The CT's have a ratio of 1000/5. What percentage of the alternator winding is protected?
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140. A power station consists of two sychronous generators A and B of ratings 250 MVA and 500 MVA with inertia 1.6 p.u. and 1 p.u., respectively on their own base MVA ratings. The equivalaent p.u. inertia constant for the system on 100 MVA common base is
A. Xa = Xs + Xe
B. Xa = Xs ? Xe
C. Xa = Xe ? Xs
D. Xa = Xs2 + Xc2
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