Question

A 2.2 KVA, 440---220 V, 60 Hz, step-down transformer has the following parameters: Rp= 3.0 Ω, Xp= 4.0 Ω, Rs= 2.5 Ω, Xs= 2.0 Ω, Rc= 60 KΩ, and Xm = 15 KΩ. The transformer is operating at full load with a power factor of 0.707 lagging. The magnetizing branch impedance can be ignored.

a) Draw the transformer’s equivalent T-circuit,

b) Find the equivalent winding impedance referred to the high side,

c) Calculate the primary and secondary currents,

d) Determine the P in and P out of the transformer.

e) Determine the efficiency and the voltage regulation of the transformer at the full load.

Answer #1

A 2.2 KVA, 440---220 V, 60 Hz, step-down transformer has the
following parameters: Rp= 3.0 Ω, Xp= 4.0 Ω, Rs= 2.5 Ω, Xs= 2.0 Ω,
Rc= 60 KΩ, and Xm = 15 KΩ. The transformer is operating at full
load with a power factor of 0.707 lagging. The magnetizing branch
impedance can be ignored.
a) Draw the transformer’s equivalent T-circuit,
b) Find the equivalent winding impedance referred to the high
side,
c) Calculate the primary and secondary currents,
d) Determine...

Three 1-φ, 100 kVA, 1730/208 V, 60 Hz transformer are connected
to form a 3-φ1730/480 V transformer bank. The equivalent impedance
of each transformer referred to the high voltage side is 0.3 + j0.4
ohms. The transformer delivers 40 kW to the load at 0.8 p.f.
leading.
a) Determine the phase and the line currents at the primary and
the secondary sides.
b) Draw the equivalent per-phase circuit refereed to the primary
side and determine the primary volt

Three 1-φ, 100 kVA, 1730/208 V, 60 Hz transformer are connected
to form a 3-φ1730/480 V transformer bank. The equivalent impedance
of each transformer referred to the high voltage side is 0.3 + j0.4
ohms. The transformer delivers 40 kW to the load at 0.8 p.f.
leading.
a) Determine the phase and the line currents at the primary and
the secondary sides.
b) Draw the equivalent per-phase circuit refereed to the primary
side and determine the primary volt

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 single phase 3kVA 480/240 V 50 Hz transformer has the
following parameters:
High voltage side: r1 = 0.25 Ω Xl1 =
0.75
Low voltage side: r2 = 0.05 Ω Xl2 =
0.18
a) Draw the equivalent circuit with
quantities referred to the low voltage side;
b) Determine the voltage regulation when the transformer
is supplying full load at 240 Vrms
and 0.9 power factor lagging;
c) If the load terminals are accidentally
short-circuited determine the currents in the high...

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