Ouch- eletrocution

Turn up the sound and you'll hear the AC in the arc..

Bit more that that 33 kV for 10 mm IIRC with spherical electrodes...

Dave the bloke wasn't playing about he was mentally deranged. Or higher than the proverbial kite on drugs....

In article , Mike Tomlinson scribeth thus

I sincerely hope Mike that you never suffer from depression which has to be experienced to be believed. Not just the pissed off 'cos I have to go into work when I don't want, or my teams lost the footer but full blown clinical depression.

People in their normal state of mind just don't deliberately kill themselves.

Next time your at the station just think how would you need to feel to jump into the path of an oncoming train?..

And yes I know what its -like- for a train driver. I met one at an inquest once and no its not a very pleasant experience for the poor sod's who have to collect the bits afterwards either..

What, just about ?

I always thought the rule of thumb was 30kV / cm

spark plug gaps are what, 20 thou? 0.5mm

A neon used as a spark gap will spark at about 90V where the electrodes are 1mm+ apart

Just found this

across a spark gap

Thanks Toby

I'm wary of using it following some comments here but I have downloaded it.

I'll post a new question about audio conversion in another thread.

AJH

On Sun, 7 Jun 2009 14:04:25 +0100 someone who may be tony sayer wrote this:-

The reasons for going for a high voltage were to do with minimising the number of feeder stations and other electrical infrastructure. With a higher voltage there are far fewer and these are fed directly from the external supply. With a lower voltage there are a few external supply points, but then there has to be a railway distribution system (usually 33kV) and frequent feeder stations.

The reason for going with AC was that the locomotive could be fitted with a transformer to easily convert the supply to a more practical voltage to feed into the equipment on the locomotive.

In the late 1940s the advantage was still with lower voltage DC systems. This simplified the equipment on the train, at the expense of a lot of infrastructure at the lineside. The 1500V DC electrification from Paris to southern France is a testament to the relative merits of the systems at the time. It was thought that developments in (mercury arc) rectifiers had made the position of relatively low voltage DC systems unassailable.

However, at the same time the French were experimenting with a line which had come into their posession from the Germans. This used an industrial frequency [1] supply and a variety of locomotives. From this came the concept of a locomotive fitted with a transformer and rectifier, the output of which was fed to standard DC motors. The locomotives were a bit erratic, due to splashing of mercury within the rectifiers, but there was promise.

The industrial frequency AC system was developed from that. By the mid 1950s it was cheaper than DC and so began to be used for new installations, but it was not so cheap as to make it worthwhile ripping out DC systems and replacing them with AC [2]. The result in France is that, roughly speaking, lines south of Paris are 1500V DC and lines north of Paris are 25000V AC. LGVs, being new lines, have all been AC lines, even in southern France.

Improvements in rectifiers involving semiconductors improved DC and AC systems, but did not alter the relative merits. For the foreseeable future the 25000V AC system will remain the standard.

Eventually semiconductors improved locomotives in another way. These days it doesn't matter whether the supply is AC or DC, though it needs to be reduced to a voltage the inverters can cope with. It comes out of these as variable frequency AC which is fed to induction motors. No more commutators to maintain, which is great.

On Sun, 7 Jun 2009 14:01:51 +0100 someone who may be tony sayer wrote this:-

As I recall the maximum current on UK "classic" lines is just under

Yes. There are photographs of the few people who have survived exposure to traction systems on one of the railway safety sites. A boy with one ear burnt off and one with very bad burns on his body come to mind.

On Sun, 7 Jun 2009 14:13:56 +0100 someone who may be tony sayer wrote this:-

Then there are the people who discover that it is not always instant death, some can live for perhaps half an hour in terrible pain. However, I doubt if knowing that would affect their actions.

On Sun, 07 Jun 2009 13:43:14 GMT someone who may be "The Medway Handyman" wrote this:-

Not all of them. features a very foolish young man. It was reported that his personal safety thermostat had been affected by lukemia. However,

presents an alternative explanation and I believe that is now considered the correct one. The ICE train is not running on a high speed line, but it may well have been running at 100-125mph.

It does say in the second video that people spotted him on the ICE. The wall between the driver and the passenger compartment is all glass in those trains, though this can be turned black when necessary. Anyone in the second half of the last coach would have been able to see the "surfer".

While few are that foolish, there are people who "surf" trains travelling at lower speeds, not always on the roof but on the sides and ends. I have heard of these "surfers" being killed in Australia, Denmark and the UK. They tend to be teenage boys.

On Sun, 7 Jun 2009 15:39:10 +0100 someone who may be geoff wrote this:-

In the case of the UK, in the early days of railways. People were used to riding on the roof of stagecoaches and they were also used to jumping off stagecoaches to retrieve a hat which had blown off. The new-fangled trains seemed little different, though they ran on iron rails and had an iron horse to propel them. The rules of early railway companies banning such things seemed quaint even 100 years ago, but they were written for a reason.

Hear hear !

Unless you've been in that position, you have no idea how bad they must feel at that point - the strange thing is, to the person in that position, the mind seems can seem perfectly clear and focussed, as they often see no solution other than their own demise.

Also holds up the trains.

My last GF said that there's no point in trying to stop the train as the wheels go through people very easily. She's had to try and repair the damage on some who didn't make a proper job of it.

It those who park a car on a level crossing, kill passengers on the train and, in some cases, cause the crossing to be closed thereby causing great inconvenience and possibly danger to the locals that are selfish.

I'm not thinking of a trip of the breaker due to overload but due to earth leakage. The auto recloser on the 11kV that feeds us trips on earth leakage. One of the insulators starting tracking over on the top of the pole outside, we wouldn't have known if we hadn't been oustide and heard it crackling, enough to make the auto-recloser cycle through it's three trips in x minutes = lock out. I think we would have been aware of the noise from inside the house if it was overload that close causeing the trip...

It's certainly an idea but not for "general release" maybe part of a targeted campagne within schools in areas where playing on the electrified railyway is a problem. I think the teachers would have to be told about and consulted before hand and some form open discussion held afterwards to talk about it.

If the footage could be used, he may not have died in vain.

Others have come up with broadly similar figures, so your memory is OK. B-)

So even though he's walking along with his head about 6" from the wire he's not likely to get zapped. His mistake was raising his hand and attempting to hold the wire, presumably to maintain his balance.

In the physics lab, we used to have a rule of thumb that

Yes, but they operate at high pressure.

In message , Andrew Gabriel writes

Not my choice of example ...

There used to be two types of pantograph used, at 25A one and a 40A one, but this was before the likes of Eurostar (and I'm out of date now). There used to have to be a pantograph or two on each engine (traction) unit, as UK rules didn't allow carrying the 25kV between carriages, but I believe EU-wide rules now do.

However, the fault current through an arc could be a good deal more than an train normally uses.

Bad burns on feet are common too, where the current exits via an arc through the soles of the trainers, often burning off some toes.