Question

A 300MVA, 20KV three-phase generator has a sub-transient
reactance of 20%. The generator supplies two parallel synchronous
motors (M_{1} and M_{2}) over a 100km transmission
line. The line has two transformers T1 and T2 at the beginning and
at the end of the line respectively. Both motors are rated at
13.0KV with X"=20%. Motor M1 has a rated input of 100MVA and M2 has
a rated input of 50MVA. The transformer T1 is rated 350MVA,
20/230KV and T2 is rated 100MVA, 220/13.2KV. Both transformers have
a leakage reactance of 10%. The series reactance of the
transmission line is 0.1ohms/Km.

a)Draw the reactance diagram of the circuit with all reactances marked in per unit. Select the generator rating as base.

b) If the motors M_{1}, and M_{2} from above
have inputs of 100MW and 80MW respectively at 13.0KV, and both
operate at unity power factor. Find the voltage at the terminal of
the generator.

Answer #1

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having an impedance per phase of 2 + j5 ?/mile. At the receiving
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Three loads are connected to the secondary side of the transformer
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A synchronous generator
and motor
are rated 30,000kVA, 13.2kV, and
both have
subtransient
reactances
of 20%. The line connecting them has a reactance
of 10% on the base of the machine ratings. The motor is drawing
20,000kW at
0.8
power-factor leading and a terminal voltage of
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Please be clear in conceot and handwriting, thank
you.
A 20 kVA three-phase synchronous machine is connected to a 480
V, 60 Hz electrical service.
The per-phase armature reactance is 80%. Armature resistance is
negligible, as are all other sources of power loss.
Part A: Motor Configuration
The machine is configured to run as a motor. Its rated mechanical
power is 20 HP and it is 94% efficient.
The motor provides rated output mechanical power.
The excitation is set such...

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