"Ice Mode" on the S Stock trains

Modern traction kit is very sensitive to repeated fluctuations in current and voltage levels. If you get ice on the conductor rails, it can create all sorts of these fluctuations - you can see it in the arcing, for example. The traction system shuts down when it senses insufficient current to keep the train going so, to prevent trains getting stalled on icy rails, the driver can switch to "ice mode", which de-sensitises the traction control monitoring system and allows the train to keep moving under the bad conditions.

The other important feature of ice mode is that it causes 200amps to be drawn though the conductor shoes on the leading car. this current, if not needed by the motors, is fed through the rheostatic brake resistor. This helps heat the conductor shoe and burn though modest ice layers. It has been a fantastic success on Southern class 375 Electrostars.

I'm sure those A-stocks have been through much worse snow than that!

looks like they'll need it.

www.buckinghamshireexaminer.co.uk/south-bucks-news/local-buckinghamshire-examiner-news/2012/02/03/chesham-coldest-place-in-the-uk-again-114018-30259149/

a really adverse area for weather.

Every car has a brake resistor so you'll be good on that front!

The most simplest way to put it as Tubeprune says: If you look at a waveform of a normal voltage intake, then look at one which has been done with ice on the rails, the waveform will have lots of 'spikes' and be all over the shop. S Stock is very sensitive and requires a substantially better electrical connection than the A Stock (Hence the new shoegear)

Dare I mention S Stocks and testing in the snow, or shall we cross that bridge when we come to it.....!?!

Could be signalling or traction current mtmikethom

Right, I am going to say somthing positive about the S stock here. Very well done to whoever made ice mode (if it was even on tonight), the S stocks from what I could see from my lovely warm A stock ran smoothly!

From my experience last night - S Stock + Snow = Massive Fail:

1) Chesham service suspended - what's the chances due to an S Stock stalled at Chesham unable to make it back up the hill?

2) My train home to Chesham diverted to Amersham (but the driver didn't bother to tell anyone no Chesham service and taxis instead), S Stock, struggled to leave Ricky, stopped, made lots of unhealthy noises before seeming to find its feet - was this the 'ice mode' being switched in?

3) Having got off at Chalfont due to the lack of proper information from the driver (official complaint coming up), wait for next Amersham, also S Stock, which exhibits the same problems as the first only it never finds its feet all the way to Amersham.

At Amersham (whilst waiting for the taxi) it appeared that the first train I'd left at Chafont had gone into the siding and then stalled attempting to leave it to head south. I watched the one I had finally arrived on attempt to leave southbound from platform 1 - this was at about half a mile an hour and appeared to be under gravity.

Conclusion:
Either the drivers have no idea how to handle these trains in 'ice mode',
Or, they are an over complicated software driven disaster totally unsuited to adverse weather, especially snow and ice.

1. No. Simply not enough S-stocks available to keep that service running without causing more delays to other branches.

2. Sorry the driver didn't make this known. And yes it probably was a brief delay whilst the mode was changed.

3. But it got you to Amersham? How were the local roads at that time - which is why the taxis were a bit hit and miss and nobody actually knew at the time where they would turn up. But you complain away.

The drivers do know how to operate the trains, and both the trains and the drivers performed better than forecast in the very heavy snowfall last night.

In my area of the country, not too far from London, local buses and taxis were suspended just after 2100hrs. Many did not restart today until after lunch.

Depends on what is being driven ;D