Question

3) A single phase, 100 MVA, 200/80 kV transformer has the following test data:

open circuit: 20 amps, with 10 kW losses

short circuit: 30 kV, with 500 kW losses

Determine the model parameters. Part of the problem is to determine on which side of the transformer the measurements are made on.

Answer #1

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 10-kVA, 250 / 100-V, 50-Hz single-phase transformer gave the
following open and short circuit test results:
Open circuit test: 250 V, 2.6 A, power factor: 0.3 on HV
side.
Short circuit test: 18 V, 80 A, input power: 240 W on HV
side.
Calculate the following:
4.1 The equivalent circuit parameters of the transformer. (6)
4.2 The efficiency at full load unity power factor. (NB the test
current is not at full load) (6)
4.3 The load at which...

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...

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 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 single phase transformer rated at
3000 KVA, 69kV, 60 Hz has a total internal impedance Zp of 127ohm,
referred to the primary side.
Calculate:
a) primary and secondary
currents
b) voltage regulation from no load to
full load for 2000 kW resistive load, knowing that the primary
voltage supply is fixed at 69 kV.
c) primary and secondary currents if
the secondary is accidentally short circuited.

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...

A 525 V to 110 V, 50 Hz, single phase transformer has
a no-load current on the HV side, of 0,5 A at a power factor of
0.36 lagging. Answer the following questions regarding this
transformer: 3.1 If a load current of 24 A flows on the LV side, at
a power factor of 0.8 lagging, find the value of the primary
current and the power factor. State the assumption and
sketch the phasor diagram representing this
situation. (10) 3.2...

1- 30-kV, three-phase transmission line has a per
phase series impedance of z = 0.05+j0.45 ohm per Km and a per phase
shunt admittance of y = j3.4x10-6
siemens per km. The line is 80 km long.
Using the nominal π
model, determine
a The transmission line ABCD constants.
b Find the sending end voltage and current,
voltage regulation, the sending end power
and the transmission efficiency when the line
delivers
1. 200 MVA, 0.8 lagging power factor at 220...

The following test data apply to a 7.5-hp, three-phase, 220-V,
19-A,60-Hz, four-pole induction motor with a double-squirrel-cage
rotor of design class C (high-starting-torque, low-starting current
type): Test 1: No-load test at 60 Hz; Applied voltage V = 219 V
line-to-line; Average phase current I1,nl = 5.70 A; Power Pnl =380
W; Test 2: Blocked-rotor test at 15 Hz; Applied voltage V = 26.5 V
line-to-line; Average phase current ll,bl = 18.57 A; Power Pbl =
675 W; Test 3: Average...

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