Question

A step down transformer converts the transmission line voltage from 220V to 22V. The number of turns in the primary coil is 5,000. If the efficiency of the transformer is 80% and the output power is 10 KW, then evaluate the number of turns in the secondary coil and input power.

Answer 1

Dear student,
$$\begin{gathered} Here,E_p=220V,E_s=22V, \\ {n}_p=5000 \\ \eta =80\%, \\ {P}_0=E_s{I}_s=10kW=10000W \\ ns=? \\ {P}_i=E_p{I}_p=? \\ As\eta =\frac{P_0}{P_i} \\ \therefore P_i=\frac{P_0}{\eta }=\frac{10kW}{80/100}=12.5kW \\ As\frac{E_s}{E_p}=\frac{n_s}{n_p} \\ \therefore n_s=\frac{E_s\times n_p}{E_p}=\frac{22\times 5000}{220}=500 \end{gathered}$$

Regards