#### Problem #2-8

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Problem #2-8

Problem #2-8
• A 480 – 120 V, 60 Hz transformer has its high
voltage winding connected to a 460 V system,
and its low voltage winding connected to a
24/32.8°Ω load. Assume that the transformer is
ideal. Determine
–
–
–
–
–
the secondary voltage
the secondary current
the primary current
the input impedance at the primary terminals
the active, reactive, and apparent power drawn by the
load
The secondary voltage
480
4
120
E p 460V
Es
115V
a
4
a
The secondary current
Es I s Z load
Es
1150
Is
4.79 32.8 A
Z load 2432.8
The primary current
Is
I s aI p I p
a
4.79 32.8
Ip
1.2 32.8
4
The input Impedance at the primary terminals
Z in' a 2 Z load (4) 2 (2432.8)
Z 38432.8
'
in
The active, reactive, and apparent power drawn by the load
S Vs I s* (115V )( 4.7932.8 A) 550.8532.8VA
P Vs I s cos load (115V )( 4.79 A)(cos 32.8)
P 462.7W
Q Vs I s sin load (115V )( 4.79 A)(sin 32.8)
Q 298.56VARS