# Mathcad - 05-03f - ⋅ = and we found previously Z eqhs...

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V fl V s = The turns ratio is: a V prated V srated = a 19.167 = Referring the secondary voltage and current to the high side: V shs a V s = I shs I s a = V shs 1.38 10 5 × volt = I shs 57.971 43.478j - amp = The primary voltage is the sum of the referred secondary voltage and the drop across the equivalent impedance of the windings: V p V shs I shs Z eqhs + = V p 144.71 6.951j + KV = V p 144.877KV = Referring the primary voltage to the low side yields the no-load voltage V pls V p a = V nl V pls = V nl 7.559 10 3 × volt = So Volt_Reg V nl V fl - V fl 100 % = Volt_Reg 4.984% = _______________________________________________________________________________ Problem 5-3f Solution : The step-down transformer is rated as follows: S rated 10000 KVA = V prated 138000 volt = V srated 7200 volt
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Unformatted text preview: ⋅ = and we found previously: Z eqhs 16.53 132.3j + ( ) Ω ⋅ = Find the voltage regulation of the transformer if it is delivering rated current at a rated voltage and a power factor of 0.8 lagging. Solution : First we must find rated current I srated S rated V srated = I srated 1.389 10 3 × amp = The actual current is at a power factor of 0.8 lagging so the angle is: θ acos .8 ( ) = θ 36.87deg = and the current is: I s I srated cos θ ( 29 ⋅ I srated sin θ ( 29 ⋅ j ⋅-= I s 1.111 10 3 × 833.333j-amp = The actual secondary voltage is: V s 7200 volt ⋅ =...
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