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There was a post on RMWeb in the past where work was being done which needed a 3rd rail isolation. All was going well until the possession was given up while they were still working!

I'm  sure it related that a SC bar had been used before work started, which protected the workers if the current was reinstated (or if it wasn't, an EMU now running went onto the isolated section with its other shoes on the live section)

This was in addition to the risk of trains running when they shouldn't have been.

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On 22/07/2019 at 17:40, jim.snowdon said:

I have a copy of the report from that testing, and if I recall correctly, the objectives were to prove that the methods for short circuiting (bars & straps) would withstand the fault current from a four rectifier substation, of which Wimbledon was one of very few, as well as establishing what the fault currents would be. Even now, there are no many four rectifier substations. Two and three are more common, and have commensurately lower fault currents.

 

Jim

Indeed and subsequently Wimbledon lost one of its rectifiers on conversion to diodes - the testing was done whilst still 4 x Mercury-Arc ISTR ……………...

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On 22/07/2019 at 16:29, Zomboid said:

I was told of how Wimbledon was used to test to destruction the capabilities of the Main DC breakers. I don't remember the details now but I think it took over 40kA to ruin at least one design. Chosen because it was on top of the grid, and all those rectifiers will get the fault up about as high as it's possible to anywhere on NR.

 

How you broke 84kA without destroying the track breakers though... Tripping the rectifier HV breakers instead?

Yes the Rectifier CB's were used as they had the double contact set-up

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On 22/07/2019 at 20:41, Trog said:

When the DC rail at Farringdon (City Widened Lines) was new one of our track gangs was working there, with no isolation needed due to the con rail not yet having been commissioned. The supervisor felt uneasy about working next to un-isolated con rail even though he knew that it was still un-commissioned. So just to be sure to be sure (him being of the Irish persuasion) he dropped a fish plate onto the con and running rails. BANG! The short apparently carried on going until the fishplate melted and dripped off the rails.

As ably demonstrated by Wimbledon PW one fine afternoon by accident whilst attempting to clamp a 1A defect …………… silly ……………. that subsequently delivered us the "exclusion zone" and the requirement to take a 3rd rail isolation when clamping such defects CR side after that ……………… I mean before CR shield and rubber gloves was more than sufficient - how feckin hard could it be !! …………….. hence as my first Q on receipt of the call from the URFDO's was "which side" followed swiftly by an expletive or sigh of relief ……………………………….

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29 minutes ago, Southernman46 said:

As ably demonstrated by Wimbledon PW one fine afternoon by accident whilst attempting to clamp a 1A defect …………… silly ……………. that subsequently delivered us the "exclusion zone" and the requirement to take a 3rd rail isolation when clamping such defects CR side after that ……………… I mean before CR shield and rubber gloves was more than sufficient - how feckin hard could it be !! …………….. hence as my first Q on receipt of the call from the URFDO's was "which side" followed swiftly by an expletive or sigh of relief ……………………………….

 

It makes you wonder how the old boys back in the days of black and white managed to wash the insulators with soap and water*. Can you imagine what H&S would say to doing that these days with the possie rail live.

 

* Why you are asking? The answer is that by removing caked on dirt particularly up under the shed (the mushroom looking bit) you reduce the current leakage across the surface of the insulating pots, must not waste the companies electricity. I have also seen very old con rail that appeared to have been painted with red oxide / red lead paint presumably to reduce corrosion. I suspect this was done a very long while ago as I have only seen traces of the paint on the underside of 1914 vintage rails.

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42 minutes ago, Trog said:

 

It makes you wonder how the old boys back in the days of black and white managed to wash the insulators with soap and water*. Can you imagine what H&S would say to doing that these days with the possie rail live.

 

* Why you are asking? The answer is that by removing caked on dirt particularly up under the shed (the mushroom looking bit) you reduce the current leakage across the surface of the insulating pots, must not waste the companies electricity. I have also seen very old con rail that appeared to have been painted with red oxide / red lead paint presumably to reduce corrosion. I suspect this was done a very long while ago as I have only seen traces of the paint on the underside of 1914 vintage rails.

I've not seen it being done in the UK, but on SNCF, I've seen 25kV insulators being washed (in situ) with a high-pressure jet. They did supply the guy with a waterproof bib & brace, but I'm not sure the sou'wester was official issue.

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Only a couple of years ago,  A Tamper was at work in a possession when it shorted a juice cable in the four foot, the juice etc had been isolated and strapped out with permits to work issued, but the rogue  live cable was part of a power upgrade scheme which had not been commissioned or signed off , No one knew or suspected it was live at the time and there were no injuries other than a fright, again one of those holes in the slices of cheese scenarios prevented an electroction.

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2 hours ago, Fat Controller said:

I've not seen it being done in the UK, but on SNCF, I've seen 25kV insulators being washed (in situ) with a high-pressure jet. They did supply the guy with a waterproof bib & brace, but I'm not sure the sou'wester was official issue.

 

I did once see that being done (and the train as well) just north of Dunbar...

 

By a local farmer with his crop spray in the adjacent field.

 

It was reported and I believe he was 'had words with'

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Does not make good reading...

 

https://www.bbc.co.uk/news/uk-wales-49892460

 

A lot of people mock Health & Safety, but in most cases the rules and procedures are there just to make sure everyone gets home safe. It seems in this case that at every turn the procedures were not followed sadly resulting in the deaths of two people.

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On 27/07/2019 at 23:34, Fat Controller said:

I've not seen it being done in the UK, but on SNCF, I've seen 25kV insulators being washed (in situ) with a high-pressure jet. They did supply the guy with a waterproof bib & brace, but I'm not sure the sou'wester was official issue.

I saw a video on TV a few years back which really surprised me. It just didn't seem right, using water to clean live electrical equipment.

 

The utility electricity company needed to clean their sub-stations, especially those near the coast where salt from the marine environment builds-up.

 

So they were using high-pressure water. I seem to recall that the water was distilled, so no impurities meant that it didn't conduct electricity (or it's ability to conduct electricity was greatly diminished, not sure). I could be wrong in this.

 

Do a YouTube search for 'Hot Line Insulator Washing'

 

 

 

 

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On 27 July 2019 at 23:34, Fat Controller said:

I've not seen it being done in the UK, but on SNCF, I've seen 25kV insulators being washed (in situ) with a high-pressure jet. They did supply the guy with a waterproof bib & brace, but I'm not sure the sou'wester was official issue.

It's done on DB as well.

 

A telling demonstration, shown to me during an NR training session, involved two electrodes and a plastic U-tube filled with nothing other than tap water. One electrode was connected to the 230V live, and the other to the neutral, plugged in and left for a while. Contrary to common expectation, the fuse did not rupture, and after half an hour, the tube was only mildly warm.

 

Clean water is not particularly conductive, the problem is when it has dissolved salts in it (in the railway context, road salt on level crossings is a serious problem).

 

Jim 

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1 hour ago, Ceptic said:

Seven Drivers, from one Depot alone, are off work due to PTSD. The number of suicides on the SWML has risen considerably. 

We always did have a fairly high level compared to other routes and the trend hasn't abated - another one on Thursday evening @ Vauxhall - although I suspect that was alcohol induced falling off platform rather than suicide which tended to happen early PM. I was sat on a train at Waterloo due to depart 5 minutes before it happened and my usual developed (due to dealing with so many) reaction of "selfish b*stard - thanks for putting another hour on my 3 hour journey" kicked in which is mainly why I got out of Ops in the first place.

 

This South Wales incident - not surprised at all - the COSS & RIMINI (I still call them that) rules are so blatantly flouted on the Network it is incredible that it doesn't happen more often …......…………..... comes from bitter experience of managing muppets that think these things are just designed to inconvenience & stop them working and don't apply to them ………………………………….

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On ‎23‎/‎07‎/‎2019 at 23:12, Trog said:

 

it would never work on the railway, as the incompetent have to be kept in a fit state to be promoted out of harms way.

Amongst signalmen, there was a rather more pithy expression used, "kicked upstairs before he can kill somebody".

 

John

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