This EN 50152-3-2 is applicable to new current transformers which are for indoor or outdoor fixed installations in tractions systems, and operated with an a.c. line voltage and frequency as specified in EN 50163. NOTE 1 – EN 50163 specifies the a.c. traction systems 15 kV 16,7 Hz and 25 kV 50 Hz. As rails of a.c. traction systems are connected to earth and included in the return current path all phase to earth voltages will be within the tolerances as specified in EN 50163. Nevertheless phase to phase voltages may be higher e.g. in autotransformer systems. Current transformers are mainly used with measurement instruments, protective devices. This EN 50152-3-2 shall also be applied to current transformers other than inductive types as far as reasonably possible. Requirements of this EN 50152-3-2 prevail. NOTE 2 – Combined current and voltage transformers are typically not used in fixed installations.