Đáp án:
\(\begin{array}{l}
a.\\
{U_1} = 40000V\\
b.\\
{P_{hp}} = 20000kW\\
b.\\
U' = 169705,6275V
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
a.\\
\frac{{{U_1}}}{{{U_2}}} = \frac{{{N_1}}}{{{N_2}}}\\
\frac{{{U_1}}}{{120000}} = \frac{{4000}}{{12000}}\\
{U_1} = 40000V\\
b.\\
{P_{hp}} = \frac{{{P^2}R}}{{{U_2}^2}} = \frac{{{{12000000}^2}.2000}}{{{{120000}^2}}} = 20000000W = 20000kW\\
b.\\
{P_{hp}}' = \frac{1}{2}{P_{hp}}\\
\Rightarrow U' = \sqrt 2 {U_2} = \sqrt 2 .120000 = 169705,6275V
\end{array}\)