XANSYS Message: 40979 [Go back to message list]
No rating yet
Rate item:

Subject: electro-thermal
Author: Mike Yaksh
Date: 2002-08-21 11:50:00

Are you trying to solve this as 2D with different boundary conditions, are
do you want to solve the 3D? The VM119 is 2D. Given that copper has a
large K you have a good size area, the heat in steady state, especially,
will redistribute itself.

At 60 Hz, the skin depth is 8.5 mm or about ,33 inches. Given that twice
of this is > .5 you might not have much eddy current effect. If you want
to solve without the AC effect, you could compute the current density
(RMS), and RSVX (see below) and apply it to model and treat it as DC.

But if you need to get the skin effect into the calculation, then at this
point it makes a difference if you want 2D ot 3D

2D. Use plane 13. build the model. (use the volt dof also, couple the
nodes in volt, input the amperage (1000*1.414 for peak)). For air. model
the air to the point where the H looks like the field around a wire
(H=2pi*amps/R) , then use the infin9 (it is simplier and you will not need
energy for an L calculation). Input RSVX (.1754E-7 O-m), set the
frequency, solve, go back in prep, change hte element type to 55, input
the heat by ldread, set the other thermal BCs, solve.

3D. Model the bar in 3D using 97s and the infinite111. You could build
a 1/2 model (.25 by 6) and include air. Model sufficient air to allow the
field to appear as a field with a circular wire (H=2pi*amps/R), and then
model the 111s. You can apply a current at a single node at one end (all
nodes on the end are coupled with Volt) and the nodes at the other end
have Volt=0. Input RSVX for the copper (.1754E-7 O-m) Solve the AC
analysis. Change the element type to 70, input the heat generation with
ldread, apply the BCs and solve the thermal.

message:

I am having difficulty solving the following problem:

I have a bus bar which is 6' long and has a cross section of .5" x 6".
There is 1000 AMPS of AC applied to the bar. The bar goes through 3
different portions of air, each of which have a different bulk temp and
convection coefficient. I have been able to model this for the
convection however I am having problems applying the current. I need to
do a thermal model in which a plot of temperature is an output. This
should include eddy current and joule heating. I have been using VM 119
as a reference however that verification file uses DC and I need it for
AC. Any help is greatly appreciated.

Regards,
Sean

Posts possibly associated with message #40979AuthorDateScore
40979electro-thermalMike Yaksh2002/08/21 
78599[THERM] Thesis on electro-thermal MEMSEvgenii Rudnyi2005/09/15 
78674Electro-thermal simulation with Workbench 10.0Peter Frei2005/09/20 
78679Re: Electro-thermal simulation with Workbench 10.0Juan J. Valle Fraga 2005/09/20 
78685Re: Electro-thermal simulation with Workbench 10.0jotto 2005/09/20