Lightning
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| posted on 7/5/10 at 11:04 AM |
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Is anyone a railway engineer
I have to earth a vehicle that runs on rails. This vehicle does not touch the rails but floats on a fluid pad of some kind. I have thought of brushes
or an earthing wheel. I just thought that electric engines must take current from rails in the reverse way. If anyone can help can you U2U me.
Steve
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coozer
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| posted on 7/5/10 at 11:07 AM |
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Where is the supply coming from? Maybe a path to earth that way?
1972 V8 Jago
1980 Z750
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skinned knuckles
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| posted on 7/5/10 at 11:08 AM |
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is there any reason why you cant earth through the liquid? or how about doind it dodgem style from above?
A man isn't complete until he's married, then he's finished
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Lightning
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| posted on 7/5/10 at 11:12 AM |
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Cant use any supply it has to be independant.
getting the Lightning current from the vehicle to the rails would have to occur in over 40 locations to form a Faraday cage....big vehicle
[Edited on 7/5/10 by Lightning]
Steve
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theconrodkid
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| posted on 7/5/10 at 11:14 AM |
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i worked on the blunderground,during a course we were told that the 3rd rail had 400 something volts and the shoe hanging down from the train acts
like a brush,cant remember too much else as my eyes were glazing over due to a lack of tea
http://en.wikipedia.org/wiki/Railway_electrification_system
[Edited on 7/5/10 by theconrodkid]
who cares who wins
pass the pork pies
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Lightning
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| posted on 7/5/10 at 11:17 AM |
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quote:
is there any reason why you cant earth through the liquid? or how about doind it dodgem style from above?
I dont think the fluid is conductive.
Dogem style is a possibility on the underside of the vehicle .
Steve
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Lightning
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| posted on 7/5/10 at 11:21 AM |
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quote:
worked on the blunderground,during a course we were told that the 3rd rail had 400 something volts and the shoe hanging down from the train acts like
a brush,cant remember too much else as my eyes were glazing over due to a lack of tea
This is the sort of thing that I am looking for. Anyone know what companies I could contact
[Edited on 7/5/10 by Lightning]
Steve
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skinned knuckles
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| posted on 7/5/10 at 11:29 AM |
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just trying to get my head round the problem and the picture i have in my head is that of a canal boat running on a mains supply. am i anywhere near
the mark?
A man isn't complete until he's married, then he's finished
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Lightning
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| posted on 7/5/10 at 11:35 AM |
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quote:
just trying to get my head round the problem and the picture i have in my head is that of a canal boat running on a mains supply. am i anywhere near
the mark?
NO !!!
I think you are pulling my leg.
One Massive truck, I mean massive, running on rails that needs earthing back through the rails. Its moved by hydaulics.
Steve
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Rosco
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| posted on 7/5/10 at 11:36 AM |
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If it's lightening protection you're interested in, can't you just work on the basis that rain and lightening go together so
everything will be wet and conductive.....
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skinned knuckles
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| posted on 7/5/10 at 11:41 AM |
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quote:
Originally posted by Lightning
quote:
just trying to get my head round the problem and the picture i have in my head is that of a canal boat running on a mains supply. am i anywhere near
the mark?
NO !!!
I think you are pulling my leg.
One Massive truck, I mean massive, running on rails that needs earthing back through the rails. Its moved by hydaulics.
well if you can't come up with a solution, i think you should give the canal boat system a try
at this point i think you should have one leg that feels significantly longer than the other
A man isn't complete until he's married, then he's finished
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theconrodkid
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| posted on 7/5/10 at 11:48 AM |
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might be worth contacting london underground and asking for details or train builders themselves?
ill have a word round and see if anyone works on the trains themselves
who cares who wins
pass the pork pies
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richardlee237
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| posted on 7/5/10 at 11:48 AM |
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Why do you need to earth it.
If the vehicle is isolatd from the world and self powered then the earth path is the vehicle itself connected to the frame of the generator.
If externally powered then you can supply and earth and neautral path by the same system.
Ships do not have earth connections everything is bolted or welded to the ship which is the earth. They are also 3 wire systems (without neutral)
If you really need to provide a sliding electrical connection then contact a cranesupplier like Morris and look at the slider systems they use.
Quote Lord Kelvin
“Large increases in cost with questionable increases in performance can be tolerated only in race horses and women.”
Quote Richard Lee
"and cars"
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Lightning
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| posted on 7/5/10 at 12:01 PM |
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quote:
If you really need to provide a sliding electrical connection then contact a cranesupplier like Morris and look at the slider systems they use.
Good idea.
It so has to be earthed. Cant say why
Steve
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richardlee237
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| posted on 7/5/10 at 12:12 PM |
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Is this something to do with your username ?
Remember the whole point of earthing is to provide an alternative low resistance path to earth to prevent the current going through you or a structure
you wish to protect.
if the vehicle is isolated from the ground then it is highly unlikely to take a lightning hit as the circuit is in complete. If you fit an earth then
you will promote the chances of being hit. Just like a car on rubber tyres
If you ar looking for a high energy (lightning) earthing sytem then you will need something pretty solid.
eg Underground sized.
But again I don't understand why you need to earth it ?
Quote Lord Kelvin
“Large increases in cost with questionable increases in performance can be tolerated only in race horses and women.”
Quote Richard Lee
"and cars"
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Dave Ashurst
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| posted on 7/5/10 at 12:16 PM |
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I can probably help you. Perhaps U2U me.
D
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mangogrooveworkshop
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| posted on 7/5/10 at 02:11 PM |
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it will have to be earthed due to it working in the proximity zone of the live overhead cables.
This is to protect both the equipment and personel working on the unit should a flashover or cable droop occur.
The means would be via a copper wheel and brushes.
The rail is a netrual earth path for the ht.
Cheers
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SteveWalker
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| posted on 7/5/10 at 02:43 PM |
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How far and how fast does this thing have to move? If it's a sort of train then earthing through the wheels, a sliding shoe or similar is your
only way, but if it's something in a factory that only needs to move slowly and for a short distance, then a fixed, self-reeling earth cable
would be practicable. Even if it is to be used on a railway line, if it only needs to be earthed while in use and then only moving up to 100m or so, a
fixed cable might make sense.
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MikeR
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| posted on 7/5/10 at 05:43 PM |
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quote:
Originally posted by Dave Ashurst
I can probably help you. Perhaps U2U me.
D
I was just thinking i know an ARUP engineer who's spent hours working on the railways .... i'll let you take this Dave, if you can't
get an answer let me know and i'll have a word with her.
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edspurrier
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| posted on 7/5/10 at 06:46 PM |
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Could consider lightning dissipators of the sort they have on aircraft.
Or an earth spike and a very long cable reel.
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richard
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| posted on 7/5/10 at 08:06 PM |
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Have to admit i work on the overground railway, apprenticeship as train maintenace fitter now in charge of the plant, services and systems we use in
the depot.
Trains use a positive pick up shoe (+750 volts ) and use the axles as a return path, underground use the forth rail as the return.
If your vehicle is running fluid has it already been suggested of using a overhard track trolly system like the conveyor system in factories.
or a fixed arm onthe side of the vehicle touching a low level contact over the side of the vehicle.
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Lightning
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| posted on 7/5/10 at 10:24 PM |
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Yes it is for Lightning Protection. We will have no problem in the earthing in the ground as this is what we do. The vehicle will effectivly be a
faraday cage. Its the connection to the rails that I need help. Ie the shoes. The vehicle is huge and will require multiple paths to earth. This is to
provide the highest level of protection in accordance with BSEN62305.
Earthing a building BTW does not increase the risk of being hit.
I cant say what the vehicle is, but it doesnt travel far.
[Edited on 7/5/10 by Lightning]
Steve
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