John B wrote:
On 1 Nov, 10:29, "R.C. Payne" wrote:
Given that one crossrail branch heads into woolwich , will the trains
be dual voltage or will they put 25KV overhead on the DC lines there?
There hasn't been a 25kV EMU built since, probably, the 322s that isn't
dual voltage under the skin. Modern power electronics means that dual
voltage units are completely trivial, basically a question of bolting on
a few shoes, and isntalling version X of the software rather than version Y.

AIUI, there hasn't been *any* EMU built [for UK rail use, pedantry
fans] since the 322s which isn't dual-voltage under the skin.

However, while all 750V stock is legally required to be easily
convertible to 25kV [see: panto spaces on the 444s and 450s' roofs],
there's no corresponding requirement for 25kV stock.

Who is responsible for this "law"? It seems a little silly to me, given
that units built for the Southern will almost certainly spend their
entire working lives on that system, and if they leave it, will need to
be replaced by something else that can work on that system.

So (for example) I imagine if you wanted to run 390s on 3rd rail,
although the power electronics could handle it, the new wiring,
finding places to stick the shoes, etc would be something of a
headache...

Certainly in the context of Crossrail, the 390s are a red herring, and I
suspect the only reason it would be difficult (apart from DC control
software not existing yet) to make them work on 3rd rail is because the
tilt gear (which has no purpose off the WCML and a few non-Southern
other bits) takes up the space that might otherwise be wanted for shoegear.

With the class 323, which is not a current design, asside, everything
else has been built either as a dual voltage unit, or as part of a
standard family that contains members of both sorts.

Robin