A comparison of the phase error of existing shunts for currents between 10 and 100 A and frequencies from 500 Hz to 100 kHz has been organized. Measurement processes were performed at Istituto Nationale di Ricerca Metrologica on some shunts using the first prototype of a new type of a phase comparator and a step-up method for data processing. Results of the relative measurement processes have shown good repeatability. The method for evaluation of reference values was based on similar shunts and suitable assumptions and derived by extrapolation. For the type of resistance elements employed in these shunts, the derivation of the reference is not very accurate and still needs to be improved.