Question 3.31: Solve Problem 3.8 using Matlab^†††††. Also calculate % volta...

Steps for computing circuit model parameters, voltage regulation and Efficiency at full load for a Transformer using MATLAB.

Open-Circuit Test The equivalent circuit as seen on open-circuit test is given in Fig. 3.23(b).

Applied voltage $=V_{1}$  (rated) Current drawn = 10

Power input $= I0$

$Y_{0}=\frac{I_{0}}{V_{1}}$, $G_{i}=\frac{P_{0}}{V_{1}^{2}}$

Short-Circuit Test The equivalent circuit as seen during short-circuit test is drawn in Fig. 3.23(b).

Applied voltage $=V_{sc}$ (a fraction of rated value)

Current drawn $= I_{sc}$ (nearly full load value)

Power input $= P_{sc} = P_{c}$ (copper loss)

$Z=\frac{V_{sc}}{I_{sc}}$, $R=\frac{P_{sc}}{(I_{sc})^{2}}$

Voltage Regulation

% voltage regulation $=\frac{voltage  drop}{rated  secondary  voltage  at  full  load  and  specified  pf} \times 100$

or,                                             $VR=\frac{I(R \cos \phi \pm X \sin \phi )}{V_{2}} \times 100$; + for lagging pf;

– for leading pf

where

I = secondary current

R = equivalent resistance referred to secondary

X = equivalent reactance referred to secondary

$\phi$ = power factor angle

Efficiency at full load

Efficiency at full load $= \frac{Full  load  output\times  100}{Full  load  output + Core  loss + Copper  loss  at  full  load} =\frac{P}{P+P_{i}+P_{c}} \times 100$

MATLAB PROGRAM