Post on 18-Dec-2015
ELECTRO MAGNETICAPPLICATIONS, INCEMADÑ
MHARNESS Wizard
Tim McDonald, PhDChristel Amburgey
May 1, 2014
ELECTRO MAGNETICAPPLICATIONS, INCEMADÑ
Preparation
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Block Diagram of Sample Cable
W1109
W1159
We must create unique names for traceability in the analysis for segments, junctions (J) and terminations (T).
T01
T02
T03
T04
T05
T06
T07T08 T09
T10
J01 J02
J03
J04 J05
J06J07
J08 J09
W1109_J01_T01
W1109_J01_J02
W1109_J02_J03
W1109_J03_T02
W1109_J03_T03
W1109_J02_T04
W1109_J01_J04
W1109_J04_J05
W1109_J04_T06
W1109_J05_T05
W1109_J05_J06
W1109_J06_T07
W1109_J06_J07 W1159_J07_J08 W1159_J08_J09 W1159_J09_T10
W1159_J08_T08 W1159_J09_T09
Lengths between connections are not to scale
Sample cable named WCM1109 connected to WCM1159 through a junction
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Compile the Inner Conductor Information
• First we compile all of the interior connection information from relevant spreadsheets/data.
Cable Connections
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Route the Inner Conductor Connections Based on Block Diagram
Take each connection and trace through block diagram segments
Number of wires TSPs, etc.
Connection numberConnection type (T=TSP)
Gauge
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Compiling Parameters
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Compiling Parameters
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Probes – Pin TransientsFor each connection, we would like to probe the pin short circuit (SC) current and open circuit voltage. We choose to probe at end 2 (for this case we should have pin to pin connectivity) and we are choosing to open the circuit at end 2 for open circuit (OC) cases. Again we choose to use the first S0 conductor in the TSP as a SC and the second for an OC.
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Running the Wizard
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Create a Simplified Cable Model in CADfix • Define units corresponding
to 3D CAD (1” cells from mesh).
• Use a short dummy length for visualization (5” segments).
• Define a time step.
• Construct a lattice around model to mesh (model must be meshed to run MHARNESS Wizard tool).
• Place all geometry in a set (sall, etc.) to mesh.
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Check Orientation of Lines
CADfix CommandPloc sens on Arrow goes from end 1 to end 2
To change orientationOrev linename
Once this is completed then put all geometry into a mesh set and mesh
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Start the MHARNESS V4 Wizard
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MHARNESS Wizard
Filename and Time Step value and number are populated automatically but user can modify
When using MHARNESS Wizard with full 3D model (not simplified cable model) you can put the set name of the cable you wish to make a MHARNESS input file for if there are multiple cables.
For now enter mesh set containing all geometry.
Select level of shielding – in this case we have TSP shielding and an overbraid so we have two levels of shielding.
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MHARNESS Wizard
Select all cables
Select all terminations
Select Boundary
Conditions for Terminations Note, in the wizard, we are
ignoring grounded connectors such as J07. We will put these in manually later.
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MHARNESS Wizard
Next the Wizard will highlight each segment in the CAD and request input
Input Segment NameEnd 1 and End 2 names (Slide 11) Note enter 0 for terminations
1 mm default
In general, we apply a source to all segments (Unless they are a dummy segment such as what is described on slide 10.) The type of source from EMA 3D is a Segment Current Drive from a datafile. We generally name the source file after the segment it is applied to.
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MHARNESS WizardAfter input each segment, you will be asked to input the total number of level 1 (in our case TSP) cables.
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MHARNESS WizardNow you will be asked to route each TSP cable. You should have the preparation material handy to help keep track of the cables.
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MHARNESS Wizard
Select segments cable is routed through
Select end points
Generally we consider the TSPs shorted to the overbraid and then tied to ground. So 1e-6 (short) or 2.5 mOhm bonding resistance is commonly used.
If you accidently miscalculate the number of cables it can be changed by this “Change Number S1 Conductors” button and BACK if you make a mistake
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MHARNESS WizardNext you will be prompted to enter the gauge and cable type. Standard values will automatically populate – these can be edited if necessary
Cable Path is highlighted
We generally assume a background of air and a jacket with a dielectric of 3 – but these can be edited
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MHARNESS WizardThen you are asked to enter the core wire dielectric (again default is 3) and the boundary conditions.
In general for lightning transient predictions, we look at short circuit current and open circuit voltage. To do this we must make two separate runs.
The short circuit run has all S0 boundary conditions shorted. The open circuit run has end 2 open and end 1 shorted.
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MHARNESS Wizard
MHARNESS then asks if the next conductor has the same routing path(if you have 18 conductors with the same routing path this will save you significant time).
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MHARNESS Wizard
Make shield larger or smaller
Navigate back and forth between segments
undo
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Additional Cable Pack Features
Visualize existing MHARNESS file(beta)
Zoom view
Output file when done
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MHARNESS Wizard• Maker sure the cables have some extra
space even though this is fictitious (MHARNESS requires this).
Note the conductor number is also shown - this is important because there is some variation in current depending upon position within the bundle.
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Consideration for Probes
For this example cable, we moved all of the probed cables to be closest to the shield (Cable 1) for the segment they are probed at. There is some variance due to cable position but in general the margin applied to the transients should account for this.
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MHARNESS WizardAfter packing the cables in Cablepack, the Wizard will highlight each cable and populate input parameters. These parameters should be checked against those calculated previously.
Previously for this segment, a resistance of 1.73 mohm/m and a transfer imductance of 1.65 nH were assumed, so we would need to edit these values
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MHARNESS Wizard
Connector Conductance
Connector Conductance
Connector Conductance
Connector Conductance
Boundary Condition
Boundary ConditionBoundary Condition
Boundary Condition
Depiction of Shield (Overbraid) and TSPs
We do not use connector conductance for this case (Shielded TSPs)
If there was a lossy material between the twisted pairs we can chose to model this using the connector conductance. Values are entered in 1/Ohms (i.e. 2.5 mOhms would be entered as 400 in the conductance matrix).
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MHARNESS WizardEnter the number of probes:
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MHARNESS Wizard
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MHARNESS Wizard
And create your .inp file!