 # Electrical Engineering Objective Questions { Alternators }

162. For proper synchronisation of a large synchronous machine to a bus, the frequency of the incoming machine

163. A 3-phase alternator delivers power to a balanced 3-phase load of power factor 0.707 lagging. It is observed that the open-circuit emf phasor leads the corresponding terminal voltage phasor by 15?. Neglecting the effect of harmonics, the angle between the axis of the main field mmf and the axis of the armature mmf will be

164. A 3-phase, 400 V, delta connected alternator has a synchronous impedance 01 (0 +j20) ohms per phase. If it delivers a balanced load of 12 kVA at zero power factor leading, then the percentage voltage regulation of the alternator is equal to

165. For a uniformly distributed winding of an alternator with a phase spread of 13 degrees, the distribution factor is

166. A single-phase alternator has a synchronous reactance of 2 ohms and negligible resistance. If it supplies 10 A to a purely capacitive load at 200V, then the generated emf will be

167. Suppose a synchronous generator connected to an infinite bus is supplying electrical power at unity PF to the bus. If its field current is now increased.sinp

168. In the phasor-diagram of a round-rotor synchronous generator, the voltage equations is Et. =V + la (ra + jXs), where Et- = excitation voltage, Vt = terminal voltage, Ta = armature current at lagging power factor, ra = armature resistance; Xs = synchronous reactance. While remaining synchronized to the bus-bars (infinite bus), if th power input from the prime mover is gradually decreased and finally stopped, it will result in

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