Track/trolley system transients

A simple yet effective method is presented for modeling a track/trolley/earth conductor system. The results from this approach can used to predict more accurately the system resistance, inductance, time constant, and transient current division between track and earth which can be used in the fuse protection of mine DC power systems. The agreement of the predicted values with measure values is shown to be better than that obtained with previously used methods for three reasons. First, the more accurate two-frequency model for the internal impedance of the track/trolley system conductors is used. Second, the external impedance model used is superior to an earlier model since the tunnel-type characteristics of the underground environment are taken into account. Third, a more accurate method is used to account for the conductor/conductor and earth/conductor interaction