Question

The primary of a transformer has 200 turns and secondary has 1000 turns. The power output from secondary at 1000 V is 9 kW. Calculate primary voltage and heat loss in primary. Take resistance of primary coil `0.2 Omega` and efficiency of transformer = 90%.

Answer 1

Here,`x_(P) = 200, n_(s) = 1000 , E_(s) = 1000 V`,
`P = 9 kW = 9000 W`
`E_(P) = ?, H = ?, R_(P) = 0.2 Omega, eta = 90%`
As `(E_(s))/(E_(P)) = (n_(s))/(n_(P)) = (1000)/(200) = 5`
`:. E_(P) = (E_(s))/(5) = (1000)/(5) = 200 V`
From `eta = (P_(0))/(P_(i)) , P_(i) = (P_(0))/(n) = 10 kW`
`:. I_(P) = (1000)/(200) = 50 A`
Energy loss in primary
`= I_(P)^(2) xx R_(P) = (50)^(2) xx 0.2 = 500 W`