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Thread: Hybrid World Rally Cars
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9th January 2016, 22:59 #25
The incident with the train is fairly easy... in that case the human is the only conductor connecting the power to earth and the super high voltage (16 kv in sweden... don't know what finnish train systems run) can actually arc the air to human due to the high voltage and conduct to earth. Just a shame that railway operators have to be responsible for these idiots... let them burn I say!
In the case of the rally car, we still have to conclude that both poles have to be earthed through the water for this to work. It is true that different kind of water conduct differently... distilled fresh water is the worst conductor and salt water the best (due to the ions and free electrons etc etc). We know that we need a relatively high voltage to create any current in a human person.
This is why 12v and 24v systems can be touched and nothing happens...
We also know that voltage in a system of resistances distribute over the highest resistor with the greatest voltage and the lesser resistors with lesser voltage when in series.
We also know that the most current pass "the path of least resistance".
Below is a very simplified diagram of the situation. In reality it is endlessly more complicated but it is a simple map to help us understand what happens.
As seen in the diagram (where I have lied a bit and connected the left hand of human to the minus pole... but hey, resistors are addable in series so), the voltage over human is distributed over water 4 (I named the waters differently but in reality as it is just one big body of water so we could all have named them the same but for understanding, better like this) and then human... so it won't be many volts over human as the body of water 4, even in salt water, have resistance per meter and cable area...
Now if human really was in series with water only and was touching the minus pole, 100% of the current would pass through human... but that is not the case because there is earth, water and body shell also in parallel and they are much preferred path of the current to take so the current passing through human will be microscopic... at best.
You need to remember that there is no ground in a battery system of a car (other than the bodyshell which is used as a common 0 of sorts... I guess you can regard that as ground but it is important to remember that it is not the ground you stand on).
The reason why trains and all other land based electricity is dangerous is because it returns through ground (yep, that is right, the 0 cables (blue) of almost all land based equipment today, including high voltage transformers etc etc, are earthed and return the current through ground... and yet you don't get fried when you put a shovel in the ground... same thing as the rally car in the water really). When you touch any live electric bit, it always wants to return to earth... which is exactly why the bird in your chart is fine even if it were to sit on a live wire where the insulation is gone... the bird does not touch earth.
I don't think your fuses would survive it and you probably have an earth fault breaker as well... so go ahead Ok no probably not, unforseen things will probably happen, but theoretically you'll be fine!
Generator tests are done without fuses and other safety equipment hahahaha, but there is a safety parameter... mostly because the pahses are live and bare and not because of the water... it is very interesting to watch
Of course Hyundai will pull the plug, Mikkelsen is in the team... Jokes aside, everyone is agreed that todays rules not working, so something has to be changed. New rules has to make shure new...
WRC main class in 2025