Make sure just the rear pan is up as you approach the neutral section. Once the front pan is clear of the neutral, lower the rear pan and raise the front one. Apart from hotel power going off for a few seconds, problem solved, surely?
25kV is a niminal figure and varies according to load being drawn elsewhere and other factors, it could be a problem of there's a voltage difference between the sides. As there has to be a very low resistance to minimise losses a few volts would lead to many many amps flowing. IIRC similar issues exist on 3rd rail with the class 73 if the front and rear shoes bridge a gap where there's a difference. Higher voltages are needed for higher speeds so when approaching country sections the voltage is increased in steps. That means there could be a large amounts of amps flowing through the loco wiring which could cause serious damage.
Not sure if the memory is playing tricks again but I thought I read somewhere that there's a sewer running under the track at a height that precludes track lowering.
It's not impossible to reroute a sewer. It might be tricky and expensive, but not impossible.
agreed, nothing is impossible if you throw enough money at it.
If the contact wires either side of the neutral section under the bridge were to be electrically connected ‘by a jumper cable’, this problem wouldn’t occur.
in a scenario of a train with 2 pantographs raised there would remain the issue of the pantograph at the neutral section being "live" from being connected through the train to the other pan which would be in contact with live OLE. The pan at the neutral section would not be electrically clear of the structure. If it was electrically clear there would be no need for it to be neutral under the bridge!
That'd be the Aerial Earth Wire. Return Current will be through an RSC in the cabling trough, I suspect - I don't think the MML's a major-enough route to warrant Auto-Transformer Feeding.
Are pans on separate vehicles electrically connected? Don't they have their own transformers to prevent this?
the planners will get this right. Let's hope the bean counters agree and fund the correct solution, with passive provision to upgrade at a later date if necessary. Rather they got it right first time though.
Agreed - Most new installation will be Autotransformer (better all round) and it also keeps the electricity transmission and distribution networks happier than traditional feeds (good for costs).
It was probably a case of the government saying ‘please electrify this line’ and Network Rail saying’OK, we’ll start at Bedford and by the time we get to the difficult bits, the designers will have a solution’.
