August 28, 20178 yr http://road.cc/content/news/228375-kent-cyclist-hospitalised-after-riding-across-live-rail
August 28, 20178 yr Oh well, look on the bright side. Maybe he'll get super powers now. He would have to have been bitten by a radioactive spider and accidently given some experimental drugs at the same time too
August 28, 20178 yr Author How much voltage/current is going through these live rails and wouldn't the rubber from the tyres insulate the rider from the electricity?
August 28, 20178 yr How much voltage/current is going through these live rails and wouldn't the rubber from the tyres insulate the rider from the electricity?If you can imagine actually riding across without putting your food down..
August 28, 20178 yr How much voltage/current is going through these live rails and wouldn't the rubber from the tyres insulate the rider from the electricity? Southern's third rail system is 500 volts DC, bike tyres don't seem to have had enough insulation resistance in this case. However he may have been riding at an angle across and had a wheel slip allowing a rim to contact. .
August 28, 20178 yr Author Southern's third rail system is 500 volts DC, bike tyres don't seem to have had enough insulation resistance in this case. However he may have been riding at an angle across and had a wheel slip allowing a rim to contact. . Any idea of how many amps these live rails are capable of supplying?
August 28, 20178 yr It's nothing to do with the tyres. His frame shorted the two rails, while the wheels were on the ground between the rails. There would have been a massive flash, which would have made him drop the bike, so then the whole frame fell flat on the rails and shorted them out. There would have been a big plasma ball, which is what would have burn't the guy.
August 28, 20178 yr Any idea of how many amps these live rails are capable of supplying? 9000 amps - enough to make a nice plasma ball. A 200 amp 48v one is pretty spectacular. I've made a few.
August 28, 20178 yr Author 9000 amps - enough to make a nice plasma ball. A 200 amp 48v one is pretty spectacular. I've made a few. Crikey
August 28, 20178 yr 9000 amps - enough to make a nice plasma ball. A 200 amp 48v one is pretty spectacular. I've made a few. Show off! I've only ever managed 100 A 37 V - I'm off to have a sulk...
August 28, 20178 yr Show off! I've only ever managed 100 A 37 V - I'm off to have a sulk... My tee-shirt looked like one of those bulls-eye ones afterwards. I wasn't burnt, but it didn't do my eyes any good. It's surprising how bright the flash is.
September 13, 20178 yr Any idea of how many amps these live rails are capable of supplying? The live rail ... probably 1million amps it is a very thick cross section and would take a while to heat up to plastic point. The train is probably drawing 100kw when accelerating. That's a guess . So typically the current will be 100kA÷500 =200amp. If it's more power them the current will be pro rata.
September 13, 20178 yr I find it hard to feel any sympathy for anyone who is daft enough to do this... This might explain why it happened. http://www.kentonline.co.uk/maidstone/news/disruption-after-motorbike-fire-131172/
September 13, 20178 yr Makes sense, our Southern third rail system on an overground line is an oddity even in Britain, and it certainly doesn't exist in the USA. .
September 13, 20178 yr The train is probably drawing 100kw when accelerating. That's a guess . So typically the current will be 100kA÷500 =200amp. If it's more power them the current will be pro rata. A train draws about 9000 amps at 500v. That's 4500Kw, not 100Kw. You're miles off. A small hatchback car can make 100Kw! At 4500Kw, a train would be equivalent to 45 cars, which sounds about right to me.
September 13, 20178 yr A train draws about 9000 amps at 500v. That's 4500Kw, not 100Kw. You're miles off. A small hatchback car can make 100Kw! At 4500Kw, a train would be equivalent to 45 cars, which sounds about right to me. You are correct .. I was away from my base when I posted.
September 13, 20178 yr Was struck by lightning in the Swiss Alps at 12000ft. Reckon I survived because my clothing was soaking wet, no goretex in them days! All our ironmongery was vibrating and sparks coming off the ends of the ice axes. The breakdown voltage of air is about 10000V per cm. It's not voltage that kills you it's current 100 ma is enough to put your heart into ventricular fibrillation. That's why the UK stuck with 240V and the the US with 110V. We don't use the electric chair to kill people. Check out the war between Edison and Tesla. Sent from my iPad using Tapatalk
September 13, 20178 yr My tee-shirt looked like one of those bulls-eye ones afterwards. I wasn't burnt, but it didn't do my eyes any good. It's surprising how bright the flash is. I had a funny event a year ago. I was grass cutting with an 1.6kw electric mower, which had a dodgy extension lead. At some stage, the wire broke within the insulation and went open circuit. It must have happened at peak current in the phase. The back EMF was such as to blow apart the internal wire insulation , the external cladding and produce a plasma flash. This instantly scorched, shriveled the skin on my little finger, which was close to the cable. The damage was extensive .. removing skin and fat covering down to the muscle layer! ...In an instant. It has recovered since, but there is still some surface sensitivity. I was lucky in that it was not another four inches further along the cable or it might have taken out my wrist tendons and major veins So d8veh, you can count yourself lucky. That it was only your teeshirt. , And I now wear gloves while handling live cables near electric motors.
September 13, 20178 yr Makes sense, our Southern third rail system on an overground line is an oddity even in Britain, and it certainly doesn't exist in the USA. . I like the idea of the third rail at ground level it's aesthetically more pleasing than gantries . But why does it need to be constantly energised ? Only small sections need to be say 0.5 mile to 1 mile segments. Similarly the underground should have the section close to the station deenergised except when the train is present.
September 14, 20178 yr Author I like the idea of the third rail at ground level it's aesthetically more pleasing than gantries . But why does it need to be constantly energised ? Only small sections need to be say 0.5 mile to 1 mile segments. Similarly the underground should have the section close to the station deenergised except when the train is present. I reckon the cost of doing that is the reason. I don't know what would be involved to switch large currents of DC voltage on in small track sections, but it does sound very expensive. Train travel is expensive enough as it is, without the companies passing on that cost to us.
September 14, 20178 yr I like the idea of the third rail at ground level it's aesthetically more pleasing than gantries . But why does it need to be constantly energised ? Only small sections need to be say 0.5 mile to 1 mile segments. Similarly the underground should have the section close to the station deenergised except when the train is present. The trouble with the third rail system is it's low voltage DC inefficiency and low speeds, compared to the 25 kV AC overhead system. .
September 14, 20178 yr I reckon the cost of doing that is the reason. I don't know what would be involved to switch large currents of DC voltage on in small track sections, but it does sound very expensive. Train travel is expensive enough as it is, without the companies passing on that cost to us. Except it's not switching large currents. When the train has not arrived at the segemnt there is no current and when it has passed there is no current.so no arcing . Sort of like a giant Hornby trainset
September 14, 20178 yr Author Except it's not switching large currents. When the train has not arrived at the segemnt there is no current and when it has passed there is no current.so no arcing . Sort of like a giant Hornby trainset I was thinking more of the cost of the circuitry to perform the switching, whether that be some kind of relay array etc.. As I say, I really don't know how they would perform selected track switching. Anyone???
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