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Time vaiable in a current flow

Posted Apr 14, 2011, 11:18 a.m. EDT Low-Frequency Electromagnetics, Materials Version 4.0a 4 Replies

Nicolas Molinier
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Hi evrybody,

So I a new user in this forum and I am new comsol user too.
I think that my problem is easy. So this is it!

At the time t=0s, my current is 50 A.
At t=1s, my current become 400 A during 100ms.
So at t=1,1s my current go down at 50 A.

I try to realise this with a rectangular signal. But I think that I forgot something but I don't know what.

So: "Elementary my dear Watson?"
Thanks a lot for your help.

Nicolas
4 Replies Last Post Apr 16, 2011, 2:40 a.m. EDT
Edgar Kaiser
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Posted: 1 decade ago Apr 14, 2011, 11:30 a.m. EDT
Hi,

it is unclear what actually your question is. Are you asking how to realize the function?

Cheers
Edgar
Hi, it is unclear what actually your question is. Are you asking how to realize the function? Cheers Edgar
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Apr 14, 2011, 2:55 p.m. EDT
Hi

if so, you might write (50+350*pulse1(t)) where pulse1() is a pulse function you can "Define" higher up

--
Good luck
Ivar
Hi if so, you might write (50+350*pulse1(t)) where pulse1() is a pulse function you can "Define" higher up -- Good luck Ivar
Nicolas Molinier
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Posted: 1 decade ago Apr 15, 2011, 3:42 a.m. EDT
Dear all,

Thank you for your quickly answers!

@ Edgar: I'm sorry to be not clear. :o) For answer to your question, I think to realise a rectangular function like this:
Name : rect1
Lower limit = 0s
Upper limit = 1,1s
Size of transition zone = 0,05s

@ Ivar: I might probably change your "pulse1" by my "rect1", isn't it?

In my global definitions, I have some parameters.
Id = 50 A
Icc = 350 A

I try to do this: (Id+Icc*rect1(t)) but it's write in orange.

I write this formula in the variable table in the global definitions menu. Is it correct?

So after that, should I use a "stationary" study or anything else?

Tks
Nicolas
Dear all, Thank you for your quickly answers! @ Edgar: I'm sorry to be not clear. :o) For answer to your question, I think to realise a rectangular function like this: Name : rect1 Lower limit = 0s Upper limit = 1,1s Size of transition zone = 0,05s @ Ivar: I might probably change your "pulse1" by my "rect1", isn't it? In my global definitions, I have some parameters. Id = 50 A Icc = 350 A I try to do this: (Id+Icc*rect1(t)) but it's write in orange. I write this formula in the variable table in the global definitions menu. Is it correct? So after that, should I use a "stationary" study or anything else? Tks Nicolas
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Apr 16, 2011, 2:40 a.m. EDT
Hi

you are right (I'm not always in fromt ofCOMSOL ;) it's the "rect()" operator

for the orange, it comes from an "Unit" issue, functions should be called in "unitless format" that is you must use:

rect(t[1/s])

to have t transformed to seconds but without units (by default it has [s] so multiplying it by [1/s] gives [1]

--
Good luck
Ivar
Hi you are right (I'm not always in fromt ofCOMSOL ;) it's the "rect()" operator for the orange, it comes from an "Unit" issue, functions should be called in "unitless format" that is you must use: rect(t[1/s]) to have t transformed to seconds but without units (by default it has [s] so multiplying it by [1/s] gives [1] -- Good luck Ivar

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