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Electric Field in a Three Phase PILC Cable Won't Solve
Posted Jun 9, 2015, 6:46 a.m. EDT Electromagnetics, Low-Frequency Electromagnetics, Materials, Modeling Tools & Definitions, Parameters, Variables, & Functions, Studies & Solvers Version 5.0 4 Replies
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I am brand new to comsol, and I've set up a simplified model of a PILC cable consisting of a lead sheath, three copper conductors and an insulating material. The insulator is a material that I created with the correct elec permativity. I am trying to solve this in the stationary domain for now, but eventually want to use the time domain to see how things change during one AC cycle.
If I set the insulator to have a conductivity of 0, the error when solved reads
"There are 3314 void equations (empty rows in matrix) for the variable comp1.V2...... "
When I set the conductivity to something like 0.0001S/m I get
"Failed to find a solution. The relative error (7.6) is greater than the relative tolerance."
I'm guessing this is due to current conservation or boundary conditions ???
I am having problems with the following:
1) How to set up the AC source in the cable, I can't find where to set the values of Current and Voltage for the three phases.
2) How to get the model to solve and plot an electric field.
In case it makes a difference, the lead I used also had some red X's next to it when I first used it, so I just set those numbers to arbitrary values.
I have attached my model to make it easier to see any problems...
Thanks in advance for any help!
Attachments:
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you have to set a potential to the wires and ground to sheath.
For an AC study you can use a frequency domain study in case the ac voltage is harmonic. You can enter complex values to take the phase shift into account.
I am attaching the modified model.
Cheers
Edgar
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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
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Thankyou for the help!
I have tried setting the potential and ground as you said but now it gives me another error:
Undefined variable.
- Variable: mef.normB
- Geometry: geom1
- Domains: 6, 7, 8
Failed to evaluate expression.
- Expression: mef.normB
- Plot: surf1 (Surface)
Unfortunately I cannot open your model, it says "model created with a later version of COMSOL." I'm running 5.0, would you be able to attach it so that I can open it ??
Many Thanks
Robbie
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You should mention the version you are using to avoid that. I saw this error too. It comes from postprocessing. Just delete the magnetic flux density plot. I am wondering where it came from since ec doesn't calculate magnetic fields.
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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
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The error might have come from an earlier stage when I had selected mef instead of ec, and it kept the plot even after i had deleted that section. For the records, I did have the version in the list of Topics, but I guess it was silly to assume someone would check there. I'll include it specifically next time.
Thank you again,
Robbie