60mph running

[Deleted]

I gather the next WTT will see Met trains timetabled to operate at 60mph in some areas, no doubt including the main lines North of Harrow and onwards to Amersham which have long been cleared for 60mph running. But will it also include anywhere else which currently has a lower line speed?

[Deleted]

Does this mean that the voltage has been upped to 750vDC then?

[julo]

Mar 5, 2013 12:35:42 GMT @hs1 said:

Does this mean that the voltage has been upped to 750vDC then?

I think the voltage will upped to 750v DC when ATC is switched on

[Zippy]

I understood the voltage would be increased once all the A stock were gone. As the S stock are software controlled, the presence or otherwise of 750v wouldn't make much of a difference.

[Weak Field]

Mar 5, 2013 13:32:14 GMT Zippy said:

I understood the voltage would be increased once all the A stock were gone.

This is certainly what we were told would happen!

One assumes they will made some mods to the remaining A Stock RAT units, they didn't want to mod the whole fleet. I gather the 1973 stock will need mods too, before 750v can be used on the Uxbridge Line.... has this occurred? been started? been deemed unnecessary? ...been forgotten??

C & D stock can and do already run on 750v

[Zippy]

I suspect for the short run RLN - UXB can stay at 630v as it doesn't really involve high speed running. I would think that the cost of upgrading the all 73 stock would far outweigh any benefits gained. If it's a case of upgrading wiring insulation it could get a bit pricey.

Of course it will involve all engineering trains too as they run out from Ruislip.

Despite what some people seem to teach, C & D stock do indeed routinely run on 750v lines

[Deleted]

Thinking about it, would a voltage increase mean a faster pull away? I'm not so sure. I haven't really seen many places at all where you can get an S stock to 60. On the fast up just from harrow yes, chorleywood on the north (I think) too.
Oh, possibly just past Neasden on the up however, 40 over the points there so do you think it's worth bringing up the speed limit before all p-way work is done? I don't think so?

[Weak Field]

I seem to recollect it was as much to do with getting all the air con units running as for traction power! Though it's the latter that has been curbed to aid use of the former! (...despite the complaints that S stock are too cold, with which I concur!!)

[Deleted]

Hmmm. HVAC units run at 400v possibly discounting your theory. I had a discussion today with someone 'in the know' and the conclusion was to enable regen braking. For anyone who doesn't know what this form of dynamic braking is, it's basically turning the traction motors into a generator which then can be used to put supply back in to the infrastructure.

[Zippy]

I gather it's more to do with overall power. If the voltage remains the same, the current draw will increase to provide for the HVAC and other stuff. If the line voltage can be increased, the extra power can be provided with no extra current flow. It's all volts times amps innit!

[Deleted]

But it's only an additional 130vDC so you won't really see any increase in performance traction package wise, I assume. I do wonder if regen brake gives you a smoother yet a better dynamic brake as we all know how rather pants the S stock rheo is. 

[metdriver]

I understand that the voltage will be raised at the same time that the line speed will be raised. As has already been mentioned, the line speed on the main north of harrow is already 60mph in places.

[Deleted]

.... only to slow to 40mph for the points in the rear of neadsen on the south. :-D

[tulip]

I'm sure that I remember that many years ago the line speed was 70mph in places, in full parallel down the bank to Neasden the speedo needle would be against the stop, and the junction signal at Wembley Park was closely watched to ensure it would clear for the NB fast!!!

[Deleted]

Christ! He said parallel! brings back a few memories that!