A 30 KVA, 2400/120V transformer has a high voltage winding resistance of 0.10 hm and a leakage of 0.022 ohms. The low voltage winding resistance is 0.10 ohms. Calculate equivalent winding resistance, reactance and impedance referred to - H.V. side - L.V side - Total copper loss of transformer -

Mumbai University > FE > Sem 1 > Basic Electrical and Electronics Engineering

Marks: 8 M

Year: May 2013, Dec 2012

Given:

KVA rating= 30 KVA

E1= 2400 V

E2= 920 V

K1= 0.1 Ω

X1= 0.22 Ω

R2= 0.035 Ω

X2= 0.012 Ω

K= E2/E1 = 120/ 2400 = 0.05

Ro1 = R1 + R2/K2

= 0.1 + 0.035/ (0.05)2 = 14.1 Ω

Ro2 = K2Ro1 = (0.05)2 * 14.1 = 0.035 Ω

Xo1= X1 + X2/K2 = 0.22 + 0.012/ (0.05)2 = 5.02 Ω

Xo2 = K2Ko1 = (0.05)2 * 5.02 = 0.013 Ω

$Za = \sqrt{Ro1 ^2 + Xo1 ^2} \\ = \sqrt{(14.02 + (5.02)2} \\ = 14.97 Ω$

$Zo2 = K^2Zo_1 = (0.05)2 * 14.97 = 0.037 Ω$

V1 ͌ E1, = 2400V

Full load current I1= KVA rating * 100/ V1

= 30 *1000/2400 = 12.5 A

Wau= I12ro1 = (12.5)2 * 14.1 = 2.2 kW