This EN50152-3-3 is applicable to new voltage transformers which are:
intended for use in indoor or outdoor fixed installations in tractions systems, and
operated with an a.c. line voltage and frequency as specified in EN50163.
NOTE1 EN50163 specifies the a.c. traction systems 15kV 16,7Hz and 25kV 50Hz.
NOTE2 As rails of a.c. traction systems are typically connected to earth and included in the return current path, all phase to earth voltages are subject to the limits as given in EN50163. Nevertheless conductor to conductor voltages are some times higher e.g. in autotransformer systems.
Voltage transformers are mainly used with:
measuring instruments,
protective devices.
This EN50152-3-3 also applies to voltage transformers other than inductive types as far as reasonably possible. Requirements of this EN50152-3-3 have priority.
NOTE3 Combined current and voltage transformers also capacitive voltage transformers are typically not used in fixed installations in traction systems.