CETU is an interference analysis utility that automates the transfer of leakage currents computed by Right-of-Way and SPLITS to a conductive analysis software such as MALZ or HIFREQ. This is useful, for example in order to carry out the conductive interference analysis required to obtain the total (i.e., inductive and conductive) interference levels. These leakage currents usually correspond to transmission line tower currents or substation ground currents injected into soil during fault conditions in substations or along the transmission lines as explained hereafter.
The induced potentials computed by SPLITS or Right-of-Way represent the inductive component of the potential impressed on the victim circuits (pipelines, rail tracks, telecommunication lines, etc.) during fault conditions. In the absence of nearby energized buried metallic structures, the local soil potential will be near that of remote soil (i.e., zero) and the stress voltages of the victim circuits will simply be equal to the induced potentials. That is typically the case when conducting a steady state interference analysis where no significant conductive interference exists.
In most cases, the victim circuit is near grounding systems such as electric substations, power plants, transmission line structures and distribution poles. Therefore, a conductive component also exists due to the energization of the surrounding soil by the current leaking from these grounding systems. Consequently, it is necessary to calculate the conductive component of the victim circuit using the MALZ or HIFREQ engineering modules of the CDEGS software package. The total potentials are then determined by combining the inductive potentials computed by SPLITS or Right-of-Way with the conductive potentials obtained from MALZ or HIFREQ.
In order to determine the conductive components of the interference, it is necessary to transfer the known fault current distribution from the SPLITS or Right-of-Way computation results to MALZ or HIFREQ. This can be done by extracting manually the required leakage currents from the inductive computation results (a lengthy operation that is prone to errors) or automatically and reliably using the CETU utility.