Although several built-in models are currently available in transient tools for transformer representation, users of these tools can develop their own custom-made models. A very common approach when developing new transformer models is to apply the principle of duality. It has been proved that a topologically-correct model of a single-phase transformer when applying duality is the so-called π model. This work is aimed at validating the π model, including hysteresis representation, for modeling single-phase transformers in ferroresonance studies by comparing simulation results and laboratory measurements.