EE 341 – ENERGY CONVERSION
1
1.
Problem 53 on textbook (Chapman, page 318)
A 480V, 200kVA, 0.8PFlagging, 60Hz, twopole, Yconnected synchronous
generator has a synchronous reactance of 0.25
Ω
and an armature resistance of 0.04
Ω
. At 60 Hz, its friction and windage losses are 6kW, and its core losses are 4kW.
Assume that the field current of the generator has been adjusted to a value of 4.5 A
(
so that the opencircuit terminal voltage of the generator will be about 477 V
).
(a) What will the terminal voltage of this generator be if it is connected to a
∆

connected load with an impedance of 5/30
o
Ω
?
(b) Sketch the phasor diagram of this generator.
(c) What is the efficiency of the generator at these conditions?
(d) Now assume that another identical
∆
connected load is to be paralleled with the
first one. What happens to the phasor diagram for the generator?
(e) What is the new terminal voltage after the load has been added?
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