350 question

[oversteer]

Was on a 350 earlier, it was accelerating away from a station when there was a thump and it stopped gaining speed, and the air con went off.
After about five seconds the air con came back on and the train started accelerating again gently.

This happened about 3 times until the train reached the next station. It was near the end of its journey and quite empty.

Tripped fuse ? What causes it?

 

[Peter Mugridge]

Neutral section?

 

[Crossover]

Yeah, sounds like the breakers for the neutral section. Can't remember technical name for them and on mobile so can't check, but it stops the unit drawing power through a neutral section, without which I believe damage could be caused

 

[O L Leigh]

Vacuum Circuit Breaker (VCB). It seems unlikely to get three neutral sections between stations, but it could be a fault or some other issue has caused the VCB to open.

O L Leigh

 

[westcoaster]

Sounds like the vcb tripping as said, but could be the wsp playing silly buggers.

 

[Crossover]

Thanks OLL

As for 3 between stations...it depends how far apart the stations are.

If it was something like within Birmingham, then it is unlikely. But if its one the 'express' services, where they do longer runs non stop, then it could be possible I guess

 

[oversteer]

Pretty sure it was just after Hemel Hempstead on the down - so, according to the Sectional Appendix*, there is a neutral section there; not sure about the subsequent ones though, the air con definitely cycled a few times. That explains the bang though

* I just spent far too long looking at that PDF considering I don't even work in the rail industry, worrying isn't it

 

[Pumbaa]

There is one there yes. But to have it three times suggests a fault. The acceleration/air con relationship is a misnomer though. The aircon takes a while to kick in after a neutral section, whereas other systems are pretty instantaneous. The driver can take power a few seconds after the line light comes back on, which can be a good 10 secs before the aircon kicks back in.

 

[33056]

There is a neutral section at Bourne End (just north of the junction) but there were (and still are) overhead line problems in the Watford Junction area so if you were on a train when the problem first started it could have been the OHL tripping out and re-setting.

 

[causton]

There is one there yes. But to have it three times suggests a fault. The acceleration/air con relationship is a misnomer though. The aircon takes a while to kick in after a neutral section, whereas other systems are pretty instantaneous. The driver can take power a few seconds after the line light comes back on, which can be a good 10 secs before the aircon kicks back in.

Aha! When I'm at North Pole on a Southern service, waiting to switch to DC, I always think "thump, the air con is off, oh god it's still off, please take power, please come back on, please don't leave us stranded here" and the unit glides away silently without the air con coming back on for a while! I thought they were usually back on at the same time

 

[oversteer]

There is a neutral section at Bourne End (just north of the junction) but there were (and still are) overhead line problems in the Watford Junction area so if you were on a train when the problem first started it could have been the OHL tripping out and re-setting.

It was at 1840ish yesterday so not sure if that's related, but it is certainly all messed up today !

 

[33056]

It was at 1840ish yesterday so not sure if that's related, but it is certainly all messed up today !

Could well have been that, the problems started around 18:45 with the 18:34 Euston to Liverpool.........