25kVAC
25kVAC is one of the most common voltages used for railway electrification, usually at 50 Hz or 60 Hz depending on that country's normal mains frequency.
This voltage is ideal for long distance use, and for new suburban railways where brand new bridges and tunnels can be built to suit.
Railways using older and lower capacity direct current systems such as Spain are introducing 25kVAC instead of 3000VDC for its new high speed lines.
50kVAC
Two isolated freight lines passing through desert country had double 25kV to 50kV to further reduce energy losses in their transmission lines.
See also
Categories: Rail stubs | Rail transport