For the transformer in Problem 3.10, the open-circuit test with \(11.5 \mathrm{kV}\) applied results in a power input of \(65 \mathrm{~kW}\) and a current of \(30 \mathrm{~A}\). Compute the values for \(G_{c}\) and \(B_{m}\) in siemens referred to the high-voltage winding. Compute the efficiency of the transformer for a load of \(10 \mathrm{MW}\) at 0.8 p.f. lagging at rated voltage.

Problem 3.10

A single-phase step-down transformer is rated \(13 \mathrm{MVA}, 66 \mathrm{kV} / 11.5 \mathrm{kV}\). With the \(11.5 \mathrm{kV}\) winding short-circuited, rated current flows when the voltage applied to the primary is \(5.5 \mathrm{kV}\). The power input is read as \(100 \mathrm{~kW}\). Determine \(\mathrm{R}_{\mathrm{eq} 1}\) and \(\mathrm{X}_{\mathrm{eq} 1}\) in ohms referred to the high-voltage winding.