Neutral Sections

[driver9000]

There is indeed a balise on the side of the track that does tell the train to cut power and then reapply it afterwards, without the driver having to operate any controls.

However it is accepted practice to shut off power at a neutral section in case the APC magnet is defective and doesn't cut the power. It also helps reduce the possibility of arcing and also stops any jolt within the train.

 

[AndrewE]

Are you possibly thinking of a now discontinued cabaret act in Benidorm?

That reminds me of the adverts for performances by Betty Swallocks that I saw in Menorca a few years ago!
--- old post above --- --- new post below ---

However it is accepted practice to shut off power at a neutral section in case the APC magnet is defective and doesn't cut the power. It also helps reduce the possibility of arcing and also stops any jolt within the train.

Really balises, or just magnets? Not long ago a friend had to go out to somewhere n of Wembley where 5 successive (electric loco-hauled, maybe freight) trains had suffered pantographs dropping. He told me that they walked the track with a detector and found that a temporarily-removed lineside magnet had been buried and lost under new ballast during track re-laying.

ps sorry, I was querying rebmcr's use of balise, not driver 9000. Quoted the wrong post! Anyway, I thought that the magnets did trigger the pan to drop. Maybe that was just on the older "analogue" locos!

 

[thecrofter]

Correct term is APC (automatic power control) magnets which operate the train circuit breaker.


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[Elecman]

Beat me to it re APCs they are not Ballises

 

[driver9000]

That reminds me of the adverts for performances by Betty Swallocks that I saw in Menorca a few years ago!
--- old post above --- --- new post below ---


Really balises, or just magnets? Not long ago a friend had to go out to somewhere n of Wembley where 5 successive (electric loco-hauled, maybe freight) trains had suffered pantographs dropping. He told me that they walked the track with a detector and found that a temporarily-removed lineside magnet had been buried and lost under new ballast during track re-laying.

ps sorry, I was querying rebmcr's use of balise, not driver 9000. Quoted the wrong post! Anyway, I thought that the magnets did trigger the pan to drop. Maybe that was just on the older "analogue" locos!

The APC doesn't drop the pantograph, it opens and closes the VCB (vacuum circuit breaker) or ABB (air blast breaker) on older locos/units.

 

[leomartin125]

There is indeed a balise on the side of the track that does tell the train to cut power and then reapply it afterwards, without the driver having to operate any controls.

Is that implemented on all electrified routes now?

 

[edwin_m]

Is that implemented on all electrified routes now?

The APC magnets have been there for many years, probably since the start of 25kV electrification. I presume there is a more modern balise-based solution as part of ERTMS but I'm not sure if it is used in the UK.

 

[coppercapped]

The APC magnets are supplied by Unipart.

Search for 'APC Magnet' and you'll find part "x0062/012011 AWS (Trackside) Magnet, APC (Automatic Pantograph Control), Rail Mount, White, Complete Assembly,"

Unless all the existing 25kV stock has been retrofitted with different sensors to work with 'balises', then the only trackside device used is a magnet.

 

[MisterT]

ERTMS provides the same kind of solution. It can be used (if implemented in the ETCS train software) to automatically open the circuit breaker and close it after the neutral section. The less 'advanced' trains only open the circuit breaker, but do not close it (yes, I'm looking at you, Bombardier ).
Not really related to neutral sections, but ERTMS also provides solutions to automatically change the used voltage. The 'old' Dutch Fyra V250 train was able to switch from 1.5 kV DC to 25 kV AC and back all by itself.