To investigate the effect of transformer energisation inrush, accurate modeling of the transformer is vital where a mathematical model must be established for numerical calculations. This paper presents a detailed transformer modelling for the slow transients study. The PSCAD/EMTDC classical transformer combined with the Jiles-Atherton nonlinear hysteresis core model is used for modelling. The developed model enables determination of the B-H curve including consideration of the saturation effects in the magnetic material. For validation, laboratory work has been carried out. A 16kVA, 250V/11kV single phase distribution transformer is used in simulation and experimentation to obtain its magnetising inrush response. Both PSCAD simulation and experimental measurements show good agreement and thus demonstrates the capability of the model to accurately represent the energisation transient. The model shows it can generate the hysteresis loop representative of the magnetic core material. For further validation, MATLAB simulation is also developed for result comparison.