- #1

Gremlin

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## Homework Statement

A 415V to 11 kV transformer has a rating of 200 kVA. The winding resistance and leakage reactance when referred to the primary are 0.014 Ω and 0.057 Ω respectively.

(b) In designing a particular 415V to 11 kV, 200 kVA transformer, the primary winding resistance is to be 10 mΩ. Find the maximum winding resistance of the secondary winding if the transformer is to have 2% regulation at unity power factor.

## Homework Equations

Voltage Regulation ≈ (VA

_{Rating}/ V

_{1}

^{2}) x R'

_{p}x 100

n = N

_{1}/ N

_{2}= E

_{1}/ E

_{2}

R'

_{p}= R

_{p}x n

^{2}R

_{s}

## The Attempt at a Solution

Voltage Regulation = 2%

VA

_{Rating}= 200000

V

_{1}= 415

V

_{2}= 11000

R

_{p}= 0.01

Cosθ = 1

2 ≈ (200000 / 415

^{2}) x R'

_{p}x 100

2/100 ≈ 1.161271 x R'

_{p}

0.02 / 1.161271 ≈ R'

_{p}

R'

_{p}≈ 0.01722

E

_{1}/ E

_{2}= 415/11000 = 0.037727

0.01722 = 0.01 x 0.037727

^{2}x R

_{s}

0.01722 / 1.42333 x 10

^{-3}= R

_{s}

R

_{s}= 1209.84Ω

I'm sure I'm wrong, but am i in the correct ball park in the way I'm going about answering the question?

Thanks.