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Do diesel fumes/particulates impact the performance of the Overhead lines?

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ohgoditsjames

ohgoditsjames

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I'm quite an observational person and when stood in a station such as Leeds or York that see a mixture of Electric and Diesel units, I've noticed the overhead lines are covered in a black tar like substance that clearly accumulates from the diesel fumes and this is apparent as it's not present at stations such as Shipley that are served for 99% of the time by electric trains.

It got me wondering, am I right in assuming it is from the diesel fumes and secondly does is it disturb the pantograph drawing current from the wire or does the pantograph simply scrape it off? The wires are clearly never cleaned as some sections are caked in this black gunk and it's most noticeable on the isolators!
 
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thecrofter

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As you'd expect, the contact wire is effectively cleaned by the carbon pan strip but the Insulators are particualrly vulnerable to arcing with the build up of carbon in stations and should be subject to a regular cleaning regime. The porcelain type are more susceptible hence the (campaign) changes over time to the more resilient (and lighter) polymeric types.
 
ohgoditsjames

ohgoditsjames

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thecrofter said:
As you'd expect, the contact wire is effectively cleaned by the carbon pan strip but the Insulators are particualrly vulnerable to arcing with the build up of carbon in stations and should be subject to a regular cleaning regime. The porcelain type are more susceptible hence the (campaign) changes over time to the more resilient (and lighter) polymeric types.
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The reason why I mention my concern for the isolators is because at the company I work for we regularly have to inspect, clean and maintain 132kV/66kV/33kV Cable sealing ends & bus bar connections at our outdoor substations/Grid Supply points of which many of them also contain oil impregnated paper too.

Some of the isolators at Leeds look like they've NEVER been cleaned!
 
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Aictos

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Mag_seven said:
I'm sure BR banned the use of steam specials "under the wires" for a time?
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I thought that was more to do with the OHL clearances then anything else?

Eg the Coronation Class were withdrawn simply because insufficient clearance between the OHL and the locomotive not forgetting being replaced by diesels.
 
Ashley Hill

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Were these flashovers taken for granted in steam days,I presume these things happened then too?Woodhead,LTS and WCML.
Slightly off topic but connected, what about when injectors overflow or blow out on 3rd rail,do they arc?
 
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jamesst

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Ashley Hill said:
Were these flashovers taken for granted in steam days,I presume these things happened then too?Woodhead,LTS and WCML.
Slightly off topic but connected, what about when injectors overflow or blow out on 3rd rail,do they arc?
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If the insulators the live rail sits on splits then theres normally a mini fire followed by a bit of a fireworks show and a loud bang!
 
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AM9

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Ashley Hill said:
Were these flashovers taken for granted in steam days,I presume these things happened then too?Woodhead,LTS and WCML.
Slightly off topic but connected, what about when injectors overflow or blow out on 3rd rail,do they arc?
Click to expand...
They would be less likely on the 1500VDC Woodhead routes, (also the Liverpool St to Shenfield/Southend Victoria lines before 1960). When the WCML around Manchester and the LT&S were first electrified, the urban sections were at the reduced ac voltage (6.25.kV) so that might have reduce the possibility as well. The video shown was on the east side of Liverpool St, after its rebuild so the OLE then would be at 25kV.
 
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twpsaesneg

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The Polymeric Insulators now used are billed as "self-cleaning" by the action of rain wash. The older porcelain insulators are subject to a cleaning regime, but it's a fairly low-priority task in the scheme of things. There is a fair amount of redundancy in the creepage path on the insulators anyway, on a dark and rainy night you can often see the odd insulator "tracking" and striking a very small arc between the "sheds" (sticky out bits) of particularly dirty or damaged insulators.

Covered stations are a bit more tricky, as the self-cleaning element of the polymeric insulators doesn't work (no rain) so it is probably better to stick with the old tech and clean them by hand!

The bushings at Feeder Stations / TSC's are generally kept in good order by the Distribution teams, and aren't as subject to contamination.

Some of the worst contamination I've seen on OLE insulators is actually from tree sap / muck, so it's not just the diesels....
 
Trackman

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Aictos said:
I thought that was more to do with the OHL clearances then anything else?

Eg the Coronation Class were withdrawn simply because insufficient clearance between the OHL and the locomotive not forgetting being replaced by diesels.
Click to expand...
I am correct in saying some classes had a stripe through the number to donate a no-go for OHL land?
 
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