Conductor Length Problem

Is this homework?

We don't do homework.

I think we should consider ceasing to inform those who ask for answers to obvious homework questions that we do not offer answers, and instead we might simply offer obfuscation.

Oh, look. Another undefined <...we...>.

We are not amused.

There is no critical lack of definition. We who need know, do.

No sir, This aint homework

It should be.

You are not ready for a real job!

<unsubscribe, with prejudice>

No I am not. So please help me. And if you cant, keep your mouth shut.

If it is homework, my guess it's a trick question and the change is negligible. There are much bigger heat sources in a panel, which don't change.

If it's a gen question, ditto!

Temperature is often related to watts produced. Then again without knowing anything about your cooling design, nothing can be determined about an equilibrium temperature.

Do your own homework! I did.

The cooling is natural. No forced cooling. The heat is dissipated at a ambient temperature of 35oC

How much liquid nitrogen do you normally use?

That the busbars are vertical is a salient feature. Since heat convection will be the dominant mode of heat transfer and also the most affected by the decrease in height, this will have the greatest affect on the panels vertical heat gradient. This is the reason it will dominate the change in the heat transfer from the panel to the environment and the change in temperature of the panel as well as the bus bar.

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Precise solutions would require some powerful number crunching for extended periods, but using the usual standard approximations of Rayleigh numbers and Prandtl numbers, dimensionless temperatures and one dimensional quasi-viscosity you can work out the transition from laminar to turbulent flow on the back of a stained napkin.

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After that the change in temperature rise shouldn't take any engineer worth his weight in salt more than an hour to burn through the numbers.

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_{The first question I had for the alien who emerged from the spacecraft was "do you have palindromes in your language?" The alien responded, "Dedno pser nei, laeht. Ega ugnal nis emordni lapev ah, uo yod. Sa Wtfa rceca. Psehtmo rfdegreoh, wneilaehtr ofda hinoits euqtsr ifeht."}

Should the OP do at least one Turbulent Prandtl number calculation to identify any possible hot spot complications?

Depending on the frequency of the power distribution there could also be magnetic induction eddy current heating effects in any ferrous hardware and shielding.

Given what has be described thus far, I can't think of a situation for which not executing at least one turbulent Prandtl number calculation wouldn't be a sign of negligence or incompetence, even at very basic levels. In case anyone needs a refresher, this is a decent refresher that should bring it all back.

Hello Sir,

Thank You for your reply. Could you please tell me in detail of how I can do this calculation??? Your help will be much appreciated.

The link in comment #15 provides all the necessary detail and example for such calculations.

Thank You Sir

Don't do that.

Next question.

Since we are to assume then I will assume the same current to be zero. So the will be no temperature rise.

Current is not zero. It is close to 3000A.

Like pulling teeth.

Don't you think that information would be necessary to give you an answer? It is the load that's causing the heat. Not the size of the panel.

Maybe you should just copy the question verbatim from the text. That way we don't get the information in dribs and drabs.

This has to be homework. And my answer seems a reasonable one.

Don't do it!

IF you have to ask, DON'T DO IT!

Nobody alters the design of a power distribution component without knowing what they are doing and the implications of their actions.

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What is your problem? If you cant give a decent answer please don't go on a vilification drive.

''Could you please tell me in detail of how I can do this calculation??? "

If you don't know how to do the job, why would you ask strangers to do the work for you?

YOU are the problem!

Have a good life.

<un-unsubscribe>

Please sir. Enough with this. Please help me. I heard this is a great community to get help regarding ELECTRICAL engineering. Please guide me.

Attached here are ABB recommendations how to calculate temperature rise in a busbar enclosure:

Could you please give me more info on this???

See:

http://www.abb-shb.de/index_abb_en_start.html

or:

http://www.scribd.com/doc/23692182/ABB-Switchgear-Manual-11th-Ed-2006

Given that there are so many variations, it is best to make a prototype and test.