scope:

This part of IEC 62505 is applicable to new voltage transformers which are:

- intended for use in indoor or outdoor fixed installations in tractions systems, and

- operated with an AC line voltage and frequency as specified in IEC 60850.

NOTE 1 IEC 60850 specifies the AC traction systems:

15 kV 16,7 Hz,

12 kV 25 Hz,

12,5 kV, 20 kV also 25 kV with 50 Hz and

12,5 kV, 20 kV, 25 kV also 50 kV with 60 Hz.

NOTE 2 As rails of AC 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 IEC 60850. Nevertheless, conductor to conductor voltages are sometimes higher, e.g. in autotransformer systems.

This document does not provide specific requirements for AC traction systems supplied with a frequency of 25 Hz or with a nominal voltage of 12,5 kV or 50 kV. Nevertheless, requirements set out in this document can be used as a guidance also for these systems.

Voltage transformers are mainly used with:

- measuring instruments,

- protective devices.

This document also applies to voltage transformers other than inductive types as far as reasonably possible. Requirements of this document have priority.

NOTE 3 Combined current and voltage transformers, also capacitive voltage transformers are typically not used in fixed installations in traction systems.