Variability of measured railway track conductance due to test set-up

The IEC 62128‐2 (EN 50122‐2) indicates methods for the measurement of rail‐to‐earth conductance and insulating rail joint efficiency in dc electrified railways. These methods are reviewed, considering the influence of system parameters on the accuracy and variability of results. This work reports characterization and quantification of uncertainty and limits of validity, as well as some practical considerations on the execution of measurements. Whereas track conductance is characterized by acceptable uncertainty in the range of one to few %, insulating joint efficiency test is deemed by a larger and variable uncertainty, so that countermeasures and provisions are necessary.