COMSOL Forums: Phase difference in current-carrying conductors

Re: Phase difference in current-carrying conductors

Tue, 23 Mar 2010 11:26:16 +0000

Hi

this says me something, we have treated that earler, try a search on the forum, sucn as animation and phasor or phase

I'm stuck in a meeting for some hours

Lykke til
Ivar

Re: Phase difference in current-carrying conductors

Tue, 23 Mar 2010 08:15:47 +0000

Hello Ivar.

Thank you for your reply.

As you say, I work in ACDC time-harmonic mode - 3D.

I have entered the following expressions for my three currents as the "Inward current flow" - Jn - boundary condition.

1000*exp(j*0*pi)
1000*exp(j*2/3*pi)
1000*exp(j*4/3*pi)

Still finding this somewhat cryptical, I would like to verify the behaviour of the currents in an animation.

I have found the "explanation" on how to animate phasors in the documentation, but I have difficulties understanding it. All my attempts result in a animation where nothing is changing.

Can you explain what I need to do?

- tore

Re: Phase difference in current-carrying conductors

Fri, 19 Mar 2010 21:33:50 +0000

Hi again

In fact, having had a second look, I assume you are in ACDC mode Time harmonic current mode, then your current flow boundary condition has a J0 [A/m^2] that chould be expressed as Jin[A/m^2]*e^(i*phase) here the imaginary part is the phase, 0, 2/3*pi, 4/3*pi for you, just check thatyou have the correct frequency too, the default is not always the one wanted.

It's explained in the doc, try the ACDCUG.PDF and search for "phase" and "phasor"

I did not find back the example I was thinking off, it could have been one from one of the COMSOL courses I have followed

Good luck
Ivar

Re: Phase difference in current-carrying conductors

Fri, 19 Mar 2010 12:39:30 +0000

Hi

quick reply with first thoughts, but one need to check carefully in the doc, if you are in time domain add a phase term to your sinus, but I would expect you to work in the hamonic mode, then I woud use the phasor for the three currents. I believe there is something like that on the forum, try a search. or was it one of the example

Will have a look again tonight, just too busy right now ;)

Lykke til
Ivar

Phase difference in current-carrying conductors

Fri, 19 Mar 2010 11:12:43 +0000

Hi.

I am building a model where 1kA, 50Hz three-phase current is passing trough a 80mm steel wall in (three..) copper conductors (r=12.5mm). The copper conductors are isolated from the steel wall with isolators (r=35mm).

The model will provide an estimate of resistive losses in the steel wall due to induced currents.

Creating and solving the model without taking the 120deg phase shifts of the currents into consideration seems easy enough.

But how do i model the 120deg phase shift between the currents?

I am not interested in the time-varying magnetic fields, only the total resistive losses in the steel wall.

Thanks in advance.

- tore