Transient overvoltage represents a high magnitude voltage surge of a short duration which has to be considered when performing proper insulation coordination. Overhead line energisation is found to be a fundamental cause of transients. Both normal and faulty conditions are possible during line energisation. The latter implies the existence of an asymmetrical phase-to-ground fault and facing with two asymmetrical processes which take place concurrently. This type of energisation results in severe overvoltage, as well as in a voltage rise at the line receiving end. However, in practice, measuring devices are usually placed at the line sending end, which points to difficulties in determination of phase-voltages at the opposite end of the line. This study offers a solution for the aforementioned issue by proposing the frequency-dependent voltage transfer functions (TFs). By using the functions any voltage value at the sending line end will obtain the corresponding value at the receiving end. The functions are derived through complex mathematical modelling and by signal processing based on the empirical mode decomposition method. The TFs validity is confirmed through performed simulation in MATLAB Simulink and real-site measurements.