A 2MVA, 2.3kV three - phase Y- connected alternator operates at rated kVA at a power factor of 80%. The dc armature winding resistance between terminals is 0.08 ohm. The field takes 70 A at 125 V from an exciter equipment. Friction and windage loss is 20kW, iron losses 36kW and stray load losses are 2.0 kW. Calculate the efficiency of the alternator. Assume the effective armature winding resistance is 120% of the DC resistance. a. 94.0 % b. 92.1 % c. 93.2 % d. 89.5 %
Synchronous Generator
In comparison to an asynchronous generator, it is a machine where the rotor speed is equal to the rotating magnetic field produced by the stator, i.e., mechanical speed is equal to the electrical speed, thus called synchronous, and not asynchronous.
Salient Pole Rotor
Salient pole rotor includes a large number of exposed poles mounted on a magnetic wheel. The construction of a bright pole is as shown in the image on the left. The proposed poles are made of metal laminations. The rotor winding is provided on these poles and is supported by pole shoes.
A 2MVA, 2.3kV three – phase Y – connected alternator operates at rated kVA at a power factor of 80%. The dc armature winding resistance between terminals is 0.08 ohm. The field takes 70 A at 125 V from an exciter equipment. Friction and windage loss is 20kW, iron losses 36kW and stray load losses are 2.0 kW. Calculate the efficiency of the alternator. Assume the effective armature winding resistance is 120% of the DC resistance.
a. 94.0 % b. 92.1 %
c. 93.2 % d. 89.5 %
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