To measure the inductance of a power transformer, you can use an LCR meter, which applies an AC signal to the winding and measures the resulting impedance. Connect the meter leads to the primary or secondary winding, ensuring the transformer is disconnected from any power source. The meter will display the inductance value directly. Alternatively, you can calculate inductance using the formula (L = frac{N^2 cdot mu cdot A}{l}), where (N) is the number of turns, (mu) is the permeability, (A) is the cross-sectional area, and (l) is the length of the magnetic path.