MHARNESS Wizard

ELECTRO MAGNETICAPPLICATIONS, INCEMADÑ

MHARNESS Wizard

Tim McDonald, PhDChristel Amburgey

May 1, 2014


Preparation


3

Block Diagram of Sample Cable

W1109

W1159

We must create unique names for traceability in the analysis for segments, junctions (J) and terminations (T).

T01T02

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


4

Compile the Inner Conductor Information

• First we compile all of the interior connection information from relevant spreadsheets/data.

Cable Connections


5

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


6

Compiling Parameters


7

Compiling Parameters


8

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.


Running the Wizard


10

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.


11

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


12

Start the MHARNESS V4 Wizard


13

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.


14

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.


15

MHARNESS WizardNext 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.


16

MHARNESS WizardAfter input each segment, you will be asked to input the total number of level 1 (in our case TSP) cables.


17

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.


18

MHARNESS WizardSelect 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


19

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


20

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.


21

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).


22

MHARNESS Wizard

Make shield larger or smallerNavigate back and forth between segments

undo


23

Additional Cable Pack FeaturesVisualize existing MHARNESS file(beta)

Zoom view

Output file when done


24

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.


25

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.


26

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


27

MHARNESS Wizard

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).


28

MHARNESS WizardEnter the number of probes:


29

MHARNESS Wizard


30

MHARNESS Wizard

And create your .inp file!

Documents

MHARNESS Wizard