Question

A step down transformer converts transmission line voltage from 11000 V to 220 V. The primary of the transformer has 6000 turns and efficiency of the transformer is 60%. If the output power is 9 kW, then the input power will be
A. 11 kW
B. 12 kW
C. 14 kW
D. 15 kW

Answer 1

Correct Answer - D
Here, `V_(p)=11000 V, V_(s)=220 V`
`N_(p) = 6000 eta, 60% , P_(o)=9 kW=9xx10^(3) W`
Efficiency, `eta = ("Output power")/("Input poers")=(P_(o))/(P_(i))`
`therefore P_(i)=(P_(o))/(eta)=(9xx10^(3))/(60//100)=1.5xx10^(4)=15 kW`