Question

A 1200 kVA, 2.3 kV, 3-phase, star - connected alternator has a resistance of 0.401 /phase and a synchronous reactance of 3.21 /phase. If the generator is supplying a load at a power factor of 0.8 lagging and at rated KVA, calculate the change in line voltage at the output terminals of the generator if the load is suddenly disconnected. Assume the speed and the excitation current is to remain unchanged.

Answer #1

A 42 kVA three-phase synchronous generator with line voltage
4.16 kV at a frequency of 60 Hz, is connected in star
configuration. The generator has a winding whose armature
resistance is 0.8 Ω and a synchronous reactance of 7.4 Ω, both per
phase. Determine the voltage regulation when the power factor is
0.600 lagging.

A three-phase, 9,375 kVA, 13.8 kV, 4-pole, 60 Hz, Y-connected
synchronous generator has a synchronous reactance, Xs = 17.9, and
is connected to an infinite bus at rated voltage. If the rotational
and electrical losses are negligivle, what is Ia, Ef, delta, theta,
Tdrive, Phasor diagram, and power flow diagram (label completely
with numerical values for,
A) the machine as a generator; the prime-throttle is opened and
If is adjusted so that the machine delivers rated kVA, 0.8 pf
lagging,...

A submarine has a 3-phase, Y-connected, 2- pole, 60Hz
synchronous generator rated to deliver 1687.5 kVA at a FP = 0.8
lagging with a line voltage of 450-V. The machine stator resistance
RS = 0.004 ?. The synchronous reactance is Xs=0.08 ?. The actual
system load on the machine draws 900 kW at FP = 0.6 lagging. Assume
that a voltage regulator has automatically adjusted the field
current so that the terminal voltage is its rated value. Mechanical
losses are...

A 3-phase, 40 MVA, 13.8 kV, 60 Hz, ?-connected alternator
requires field current of 250 A to produce an open circuit rated
voltage while a field current of 150 A is required to produce short
circuit rated armature current. Neglect armature resistance.
Determine the Synchronous Reactance (Xs).

a) A three phase transformer rated at 30 MVA 10 kV(Δ)/1 kV(Y) is
supplying a load at the low voltage side. The load absorbs 5 MVA,
0.7 power factor lagging at line to line voltage 0.9 kV. The
transformer has an equivalent reactance 0.05 Ω/phase. Assuming 10
MVA and 1 kV as base value, draw the per unit diagram for the
system. Find the Line to Line voltage at the primary side of the
transformer.
b) A three-phase synchronous generator...

The 400 V, 50 kVA, 0.8 power factor leading delta connected
synchronous motor has synchronous reactance of 3-ohm, resistance
neglected. It is supplying a 12-kW load with initial power factor
of 0.86 lagging. The windage and friction losses are 2.0 kW and the
core losses are 1.5 kW. Determine
(a) the motor efficiency; the line current; armature current;
and excitation voltage.
(b) If the flux of the motor is increased by 20 percent
determine the excitation voltage; armature current; and...

A 3-phase, 1.2 MVA, Y-connected, 6.6 KV, 6-poles, 60 HZ,
synchronous generator has a synchronous reactance of 30W and
negligible resistance. The generator is connected to an infinite
bus at 6.6 KV and 60 Hz.
a)Determine the excitation voltage (Ea) when the machine is
delivering rated power at o.8 PF lagging.
b)The field excitation current is increased by 10% without
changing the power input from the prime mover. Find the stator
current (Ia), the power factor and the reactive power...

A three-phase wye-connected (Y) synchronous generator is
operating at Ea = 8.OLO° kV (lineneutral) and has synchronous
reactance of X~ = 1.0 fl . The generator is connected to a
threephase delta-wye connected step-down transformer that is
constructed from three individual single-phase transformers. Each
the single-phase transformers has rated power of 200 kVA has a
turns ratio of 4:1 where the rated primary voltage of 8.0 kV and a
rated secondary of 2.0 kV and a per-unit series reactance of...

Use MATLAB:
A three-phase Y-A transformer is rated 225-kV:24-kV, 400 MVA and
has a series reactance of 6.08 Ohms as referred to its high-voltage
terminals. The transformer is supplying a load of 375 MVA, with
0.89 power factor lagging at a voltage of 24 kV (line-to-line) on
its low-voltage side. It is supplied from a feeder whose impedance
is 0.17 + j 2.2 Ohms connected to its high-voltage terminals. The
total load in the system remains constant at 375 MVA....

A 4- pole, 50 Hz,
Y-connected, 3-phase generator has a phase voltage of 260 V ∠0°, a
synchronous reactance of 0.06 Ω, a stator resistance of 0.003 Ω,
and Lsf= 0.02 H. The generator is directly connected to a balanced
3-phase load that draws 2 MW at a lagging 0.8 power
factor.
Sketch the
equivalent circuit annotating all the components, currents and
voltages on the diagram
Calculate the
3-phase apparent power of the load in rectangular form
Calculate the
generator...

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