Exam2-Fall07 - EEL 3211 Test 2 Oct. 16, 2007 Time limit: 50...

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EEL 3211 Test 2 Oct. 16, 2007 Time limit: 50 minutes Hint: Problems 1 – 3 are simple one-liners. Problem 4 is almost a one-liner. 1. (15 points) The core of a transformer has a cross-sectional 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 resistor to an impedance of 75 . Calculate the required turns ration assuming that the transformer is ideal 3. (15 points) A 100 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 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.

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