141.  Test (A) No load and Blocked rotor test (B) Sumpner's test (C) Swinburn's test (P) Transformer (Q) Induction machine (R) Synchronous machine (S) DC machine
A. A - Q; B - R; C ? S
B. A - R; B - Q; C ? P
C. A - R; B - Q; C - R
D.

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142. Higher synchronous reactance is preferred in the present day alternators, because one can have
A. reduced sub-transient currents
B. reduced harmonic currents
C. reduced transient currents
D. higher voltage regulation with load

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143. A there phase alternator is wound with a 60 degree phase-spread armature windings and develops 300 kVA. If the armature is reconnected utilizing all the coils for single phase operation with a phase spread of 180 degrees, the new rating of the machine is
A. 100kVA
B. 200kVA
C. 250kVA
D. 300kVA

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144. The phase sequence of a three-phase alternator will reverse if
A.2.6
B.(c) 1.625
C.3.625
D.4.625

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145.  A single-phase, 2000 V alternator has armature resistance and reactance of 0.8 ohms and 4.94 ohms respectively. The voltage regulation ofthe alternator at 100A load at 0.8 leading power-factor is
A.7%
B.-8.90%
C.14%
D.0%

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146.  Xd, X'd and X"d are steady state d-axis synchronous reactance, transient d-axis reactance and sub-transient d-axis reactance of a synchronous machine respectively. Which of the following statements is true?
A. Xd > X'd > X"d
B. X"d > X'd > Xd
C. X'd > X"d > Xd
D. Xd > X"d : X"d

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147. A 75 MVA, 10 kV synchronous generator has Xd = 0.4 p.u. The Xd value (in p.u.) to a base of 100 MVA, 11 kV is
A.0.578
B.279
C.0.412
D.0.44

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