Transformer Operation(Ideal)

e1 = N1. df ------- 1

dt

e2 = N2. df ------- 2

dt

from 1 & 2 Þ e1 = N1

e2 N2

Þ V1 = N1 = a ------- A

V2 N2

F = NI

N1.I1 – N2.I2 =0

I1 = N2 ------------- B

I2 N1

Example

N1= 1000, N2 = 10, I1=200A, I2 = ?

V1 = 100KV, V2 = ?

Equation B I1 = N2 Þ 200 = 10 Þ I2 = 20,000 A

I2 N1 I2 1000

Equation A V1 = N1 Þ 100*1000 = 1000 Þ V2 = 1KV

V2 N2 V2 10

P=VI Cos f Watts

Example For a transformer Cosf = 0.9 , V1 = 120 KV , 10MVA

a = 10, I1 = ?, I2 = ? , V2= ?

S= VI Þ s = V1.I1 = V2.I2. = 10 * (10**6)

N1 = 10 = V1 Þ 120*100 = 10

N2 V2 V2

Therefore V2 = 12KV

h = 0utput Power *100%

Input power