NotATrainspott
Established Member
- Joined
- 2 Feb 2013
- Messages
- 3,224
Power supply on Electric can be limited. I believe its been said on this board many times that 750vDC provides insufficient power for the newer trains with their air conditioing and various hotel power requirements and and the train is limited by the technology on how much power it can draw.
Even on 25KVac there are limits in some areas. 12 carriage operation to Cambridge from Kings Cross has only come into vogue in recent years. Due to the way BR electrified London to Cambridge routes in the 1980s as agreed by the Tory government of the time there was insufficient power east of Royston to allow 12 car operation in service. There still remain limits to the number of electric trains allowed to operate beyond Cambridge North Station to Kings Lynn.
Between Leeds and Skipton too there was a ban on Class 91 operation - again until recent years due to insufficient power in the overheads (Operation to Bradford Forster Square permitted).
Indeed, and this is a live issue on the ECML now. Unless there's a power supply upgrade, then it won't be possible for yet more bi-modes to run on electric power.
Practically speaking 25kV AC does enable essentially unlimited power. The feeder stations are sufficiently few and far between that they can be run directly off of the main National Grid with its enormous transmission power. If 25kV AC can't provide enough power for your rail application, then you're probably also going to be limited by other concerns. For instance it probably isn't enough to allow you to run high speed bulk materials services, but then you've got bigger problems with track wear. Several kilometre long high speed passenger services are also rather unlikely.