Electrostar v.s Neutral Sections

[ChristopherJ]

I’ve been meaning to ask regarding Electrostar trains and neutral sections.

Why do Electrostar EMUs exert a violent shudder sensation when passing through neutral sections? I've noticed it is a universal phenomenon with all 25kv AC Electrostar models: classes 357/377/378/379 respectively.

When an Electrostar enters a neutral section the components underneath the vehicle go silent – I imagine that’s elements including the motor and auxiliary converter modules and transformer shutting down, there is then a momentarily shudder sensation like the train is receiving a kick up the rear as the train transits through the section, after negotiating the neutral section all the underslung components spring back in to life again.

I have noticed the slower the train is travelling through a neutral section the more violent the sensation: travelling at 35mph through the neutral section at Coppermill Junction on the West Anglia line it is noticeable but not a cause for concern but the other day my 379 passed through the neutral section to the up-side of Hackney Downs at about 5mph after restarting from a signal and it was violent enough to knock over my can of drink on the table.

I did ask a c2c driver about this topic once but he couldn't give me a defiant technical answer, all he replied with was that it was such a minor issue that Bombardier won't even bother to rectify it.

 

[slick]

This is something I've always wondered as well as I drive them. In fact in the section that you describe you can actually feel the rear VCB open shudder the whole train on in a 8car 379. I know it has something to do with the vacuum circuit breaker opening but I'm not sure why when it does, it does it so violently. I've had a few passengers ask me what it was and that it frightened the life out of them but I've never been able to give them a technical answer.

 

[samuelmorris]

You should try standing directly underneath the pantograph when it happens. The noise is frankly excessive - it usually raises comments from people. I point blank refuse to travel in the PTOSL for this reason. This is true of all AC electrostars, including 378s by the way. It seems a shame as an otherwise quiet and refined unit is marred by this occurrance. It's not an issue on Desiros, nor is it an issue on any older EMUs either.

 

[edwin_m]

I think we may have two different things here. Are we talking something that sounds similar anywhere in the train or something which is distinctly louder under the pantograph?

I have no recollection of this in my occasional travels on these units, but I suggest if whatever happens is equal in all coaches then it's probably not to do with the traction systems since these are unevenly distributed. It sounds like some kind of largeish rotating component suddenly restarting, perhaps the fans in the aircon?

 

[samuelmorris]

After the power is restored there is an audible indicator of something large and mechanical powering up - this, however, also occurs if the train has been at a stand outside a station for some time (say, more than 1 minute), and upon first departing a terminus. It appears to come from underneath each carriage.

 

[bronzeonion]

I remember once sitting under the panto on a 378 passing through the Camden Road neutral section and a group of well 'ard innit types were sitting opposite. BANG goes the train and they all jumped out of their seats!! Hahaha

 

[heart-of-wessex]

You should try standing directly underneath the pantograph when it happens. The noise is frankly excessive - it usually raises comments from people. I point blank refuse to travel in the PTOSL for this reason. This is true of all AC electrostars, including 378s by the way. It seems a shame as an otherwise quiet and refined unit is marred by this occurrance. It's not an issue on Desiros, nor is it an issue on any older EMUs either.

Tell me about it! Scared the living **** out of me when I heard it, sounded like the panto exploded!

Had this in the PTOSL on a FCC 377/5 once at Farringdon too, when the panto dropped you sure heard it!

I seem to recall the 350's making a loud noise when I did one on the WCML too, can't remember...

 

[Clip]

I remember once sitting under the panto on a 378 passing through the Camden Road neutral section and a group of well 'ard innit types were sitting opposite. BANG goes the train and they all jumped out of their seats!! Hahaha

It is bloody loud on there though - same happenned to me and its not nice when you're not expecting it as you got your headphones in and engrossed in a book.

 

[bronzeonion]

It is bloody loud on there though - same happenned to me and its not nice when you're not expecting it as you got your headphones in and engrossed in a book.

Oh it is, but the reaction was truly priceless

 

[DownSouth]

After the power is restored there is an audible indicator of something large and mechanical powering up - this, however, also occurs if the train has been at a stand outside a station for some time (say, more than 1 minute), and upon first departing a terminus. It appears to come from underneath each carriage.

That could be the air compressor refilling the braking system.

 

[robby p]

Add Content

 

[jopsuk]

They are noticably much, much louder than 317s, 321s and 365s (based on my main use of AC trains being out of Cambridge!)

 

[slick]

I think we may have two different things here. Are we talking something that sounds similar anywhere in the train or something which is distinctly louder under the pantograph?

I have no recollection of this in my occasional travels on these units, but I suggest if whatever happens is equal in all coaches then it's probably not to do with the traction systems since these are unevenly distributed. It sounds like some kind of largeish rotating component suddenly restarting, perhaps the fans in the aircon?

No this loud thump only comes from the top of a pantograph well on the pantograph car. It is the Vacum circuit breaker opening. But its considerably louder on electrostar units. Im in today so if i catch a bombardier fitter i shall ask him.

I remember the first time I went through a neutral section whilst braking on a 379 at low speed. The mixture of the VCB thump and regen kicking out I actually thought I was pulling the wires down!

 

[Kentish Paul]

Not sure about the underfloor rumblings on a standstill change, but the transition of a neutral section at speed in a 395 on HS1 produces a hell of a bang if seated under the active pantograph. Had to calm some tourists a few days ago who thought the worst. A 378 is just as bad if seated under the pantograph.

 

[Pumbaa]

350s are a heck louder than 377/2s, and I assume therefore /5s. Cannot comment on 379s. You can hear a 350 VCB very well at the other end of the car...

 

[samuelmorris]

That could be the air compressor refilling the braking system.

Nah, different sound. This spools up much slower than the compressor (audible for about 2 seconds - and inaudible once it has powered up, versus about a third of a second for the latter, which remains audible until it is shut off). Likewise you never hear the noise I'm discussing here at speed unless possibly having traversed a neutral section slowly, whereas you could of course hear the compressor cut in at any time.

Interesting comment about the 350s, I've sat underneath the pantograph in a 360/1 and it was nowhere near as bad as a 357 or 378. Can't comment on 377 as I've not travelled any further than Farringdon - St Pancras on an AC-powered unit of that class.

 

[swtandgw]

That explains why my first time riding a 377/2 while under the pantograph well of the PTOSL made me jump every time it went past the neutral sections of the WCML, yet the times I've ridden a Pendo, an AC Desiro and countless Mk3 EMUs weren't as bad!

 

[Bald Rick]

Punters on FCCs 1W90 tonight got a full and detailed explanation of the operation of "VCBs in the pan cars" that would happen "at the four neutral sections en route to Bedford" from a rather keen driver. Same driver has done this before, and the comments in my coach tonight were along the lines of "what was he going on about?" and "I think he's on drugs".

He also had some choice comments to explain why he had to drive slowly through Kentish Town, but that's for my memoirs.

 

[asylumxl]

Punters on FCCs 1W90 tonight got a full and detailed explanation of the operation of "VCBs in the pan cars" that would happen "at the four neutral sections en route to Bedford" from a rather keen driver. Same driver has done this before, and the comments in my coach tonight were along the lines of "what was he going on about?" and "I think he's on drugs".

He also had some choice comments to explain why he had to drive slowly through Kentish Town, but that's for my memoirs.

I've had this driver before, an older chap. Can't win with commuters though! They complain they never get enough information, yet when they are given plenty they aren't interested .

 

[Skoodle]

The MCBs knocking in and out on DC also cause a racket! Try sitting at the rear of a 378 as you enter Surrey Quays on the down

 

[W230]

I've had this driver before, an older chap.

I work with him. If you're lucky he sometimes turns it into a coach tour!

 

[matchmaker]

The MCBs knocking in and out on DC also cause a racket! Try sitting at the rear of a 378 as you enter Surrey Quays on the down

Back in the early 1970's when I travelled into school on the North Clyde Line (all 303's in these days), it was sometimes the case if the train was very busy the guard allowed passengers into the guards van. Which was directly below the panto and air blast breaker. The first time we reached the neutral section at Finnieston I nearly jumped out of my skin!

 

[zn1]

the Loud bang that is heard is the VCB/ABB literally blowing the current off the vehicle. as the set/loco approaches a Neutral section the Driver is supposed to drop the power down to zero and coast through...They dont technically have to do it except if they dont you as a passenger feel the train punch and kick as the power falls off and on suddenly, in older stock and locos it could cause damage to the power equipment if this wasnt done..

the APC Magnets close the power off ,yellow magnets next each running rail, the train glides through unpowered and the APC kicks the power on again..the Pan never Comes down..its a bit of a loud bang, in the am 2-12 the bang was very loud in Brake vans...Nothing to worry about..

on 302-312 if memory serves ABB's were used, same for class 81-87.

In 313-315 the pan sits on the PTS, hence 313's can run without it and run DC ONLY.

on 317 322 the Pan is situated PMOS(pmos handles all power and has an auxilary compressor) and the VCB sits above your head in the lower roofed section of the unit as the 317-322...the sound is a little quieter as its a VCB

The sound never bothers me...its re-assuring to know all is working...

 

[rdeez]

I seem to recall the 350's making a loud noise when I did one on the WCML too, can't remember...

This does happen on 350s! You're in for a shock if you're sat on one of the side facing seats by the loo where the pantograph is. The first time I heard it I nearly fell off my seat. Extremely loud bang. Still scares me if I'm sat there distracted and not expecting it.

 

[TEW]

The MCBs knocking in and out on DC also cause a racket! Try sitting at the rear of a 378 as you enter Surrey Quays on the down

I always find on 450s you notice the neutral sections more for the lack of the noise than the noise, a brief moment of quiet which makes you realise how loud it actually is normally.

 

[455driver]

I always find on 450s you notice the neutral sections more for the lack of the noise than the noise, a brief moment of quiet which makes you realise how loud it actually is normally.

450s dont go through neutral sections!

When they 'gap' the Air con powers down and the vents close and then re-open when the train regains power, this can be heard in all coaches not just the motor coaches.

 

[TEW]

I meant gaps rather than neutral sections. And it's the air con which you realise is so loud.

 

[samuelmorris]

Amusing timing - from c2c's twitter feed today:

Joel Lucas ‏@Joelslucas 6h
@c2c_Rail how comes the third carriage makes a loud popping then hissing sound everytime?
Expand
c2c Rail ‏@c2c_Rail 5h
@Joelslucas you're sitting under the 'pantograph' that noise is when you pass from one overhead line section/area to the next.
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9:20 AM - 23 Oct 13 · Details