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EEL 3211
Test 2
Oct. 16, 2007
Time limit: 50 minutes
Hint: Problems 1 – 3 are simple oneliners. Problem 4 is almost a oneliner.
1.
(15 points) The core of a transformer has a crosssectional area of 15 cm
2
and is operated
at 60 Hz from a 120 volt (rms) supply. Calculate the number of turns required to achieve
a peak magnetic flux
density
of 1.8 T in the core.
2.
(15 points) A transformer is to be used to transform the impedance of an 8
Ω
resistor to
an impedance of 75
Ω
. Calculate the required turns ration assuming that the transformer
is ideal
3.
(15 points) A 100
Ω
resistor is connected to the secondary of an ideal transformer with a
turns ratio of 1:4 (primary:secondary). A 10 volt (rms), 1 KHz source is connected to the
primary. Calculate the primary current and the voltage across the 100
Ω
resistor.
4.
(15 points) The resistances and leakage reactance of a 30kVA, 60 Hz, 240V:2400V
(primary:secondary) transformer are:
12
0.6
8
0.0068
7.
8
0.0068
LL
RR
XX
=Ω
=
Ω=Ω
Where the “1” subscript denotes the 240 V winding and the “2” subscript denotes the
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This note was uploaded on 07/28/2011 for the course EEL 3211 taught by Professor Staff during the Summer '08 term at University of Florida.
 Summer '08
 Staff
 Volt

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