Question

A delta connected balanced load with impedance "20 - j15" is connected to a star connected generator in positive sequence with Van = "107.43 - j312". Calculate phase and line currents and voltages, also draw the configuration described with the voltage and current labels.

Answer #1

A balanced ?-connected load has an impedance of 60+ j45 ? per
phase. The load is fed through a line having an impedance of 0.8+
j0.6 ? per line. The phase voltage at the terminals of the load is
???????? = 480 ?? . The sequence is positive. Use AB v as the
reference at the load. The source is required to be calculated for
either Wye or Delta connection. a) Draw the 3-phase system b) Draw
the a-phase equivalent...

A Wye-Delta transformer is connected to a 66 kV input
three-phase transmission line. Each transformer is rated at 1000
kVA and has a step-down ratio of 8:1. The bank supplies a balance
load having a power factor of 0.8 lag with a load current of 70 A.
Assume ideal transformer, determine.
The primary line and phase voltages
The secondary line and phase voltages
The secondary line and phase currents
The apparent and active power at the load
Total kVA capacity...

calculate the line and neutral currents for the following
unbalanced wye-connected impedances:
Zan = 2 + j5 Ω
Zbn = 8 + j0 Ω
Zcn = 1 - j15 Ω
the voltage source is a balanced three-phase system, 208 V line
to line. Assume an abc phase sequence and use Van as the reference
phasor.

A balanced wye-connected three-phase source has line-to-neutral
voltages of 400 V rms.
- Find the rms line-to-line voltage magnitude.
- If this source is applied to a wye-connected load composed of
three 33 Ω resistances, find the rms line-current magnitude.
- If this source is applied to a wye-connected load composed of
three 33 Ω resistances, find the total power delivered.

A 100 MVA, 13.2 kV three phase generator (G) having a
synchronous reactance of 10% is connected to a three phase Y-Y
transformer T1 which feeds a 132 kV 10 miles transmission line
having an impedance per phase of 2 + j5 ?/mile. At the receiving
end of the transmission line is a Y-Y step down transformer T2.
Three loads are connected to the secondary side of the transformer
T2. Loads are as follows:
Load#1 40 MVA at 0.8 pf...

A feeder having an impedance of 1.0+j3.2ohms is connected to the
primary side of a step-down three phase transformer rated at
132:22KV, 200MVA and that has a series reactance of 0.14pu. The
transformer supplies a load of 190MVA with a 0.90 lagging power
factor at rated voltage.
a) Caculate the per unit impedance of the feeder and the per
unit load current. Use the transformer ratings as base values.
b) Calculate the voltage at the sending end of the feeder...

Problem 2. A three phase transformer rated at 5 MVA, 115/13.2 kV
has a per phase series impedance of 0.007 + j0.075 per unit (shunt
parameters are ignored). The low voltage side is connected to a
short distribution line which modeled by a series per phase
impedance of 0.02 +j0.1 per unit on the base of 10 MVA. The line
supplies a balanced three phase constant impedance load at 4 MVA,
13.2 kV with power factor of 0.85 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...

•The 3-phase system consists of a generator, circuit breaker, power
transformer and extra high voltage transmission line.
•The generator is rated at 60Hz, 1559Mva and 24kV. The
sub-transient reactance is 2*%. The winding connection is wye with
the neutral grounded.
•The transformer is a 1550Mva, 3-phase, shell type, 2-winding
transformer with a 24kV delta winding and a 525kV grounded wye
winding. Neglect saturation and core losses. The exciting current
is 1.0% of the rated current. The capacitance of each low...

A 100 KW (OUT PUT), 3300V, 50 Hz, 3-Phase star connected
induction motor has a synchronous speed of 500 rpm. The full load
slip is 1.8%and full load power factor 0.85. Stator copper
loss=2440W. Iron loss=3500W. Rotational losses= 1200W. calculate
:
The rotor copper loss
The line current
The full load motor efficiency.

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