Question

[12 marks] 2.(30 marks] a) Description of Core Loss in synchronous generator. When does the loss occur? [6 marks] b) A 3 phase, 2 poles, 4.16 kV, wye-connected synchronous generator with 50 Hz is applied as an emergency power source to supply 500 kW at a power factor of 0.9 lagging. The stator resistance is 0.3 Q/phase. Rotational losses in the machine are estimated to be 15 kW. Determine the required horsepower and torque of the prime mover. [12 marks] c) A 3 phase and wye-connected synchronous generator with the following parameters is considered P 150 MW,v 12.6 kV.f -60H2,( 1800 rpm, PF 0.85 The armature resistance is 1.535 m2 and the field current Ir -700 A. The SCC and OCC tests for measurements of armature current IA and intemal generated voltage EA are described in the Table 1 below: Table 1. OCC and SCC tests 700 800 Es (kv) 5.8 7.89.811.3 12.6 13.5 9.2 A(A) 34 46 5.8 79 809 4.6 If a load is connected to the generator, i. Determine number of poles for the generator's design.

Answer 1

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5.349 kW US sof