DEMA MHARNESS Wizard Tim McDonald, PhD Christel Amburgey May 1, 2014 ELECTRO MAGNETIC APPLICATIONS, INC DEMA Preparation ELECTRO MAGNETIC APPLICATIONS, INC DEMA ELECTRO MAGNETIC APPLICATIONS, INC Block Diagram of Sample Cable Sample cable named WCM1109 connected to WCM1159 through a junction T02 T01 W1109_J03_T02 J03W1109_J03_T03 T03 W1109_J02_J03 W1109_J01_T01 J02 J01 W1109_J01_J02 W1109_J02_T04 T04 W1109 We must create unique names for traceability in the analysis for segments, junctions (J) and terminations (T). W1109_J01_J04 J04 W1109_J04_J05 J05 W1109_J05_T05 T05 W1109_J05_J06 W1109_J04_T06 W1109_J06_J07 J06 T06 W1159_J07_J08 W1159_J08_J09 J07 J08 J09 W1159_J09_T10 W1159 T10 W1109_J06_T07 W1159_J08_T08 W1159_J09_T09 Lengths between connections are not to scale T07 T08 T09 3 DEMA ELECTRO MAGNETIC APPLICATIONS, INC Compile the Inner Conductor Information • First we compile all of the interior connection information from relevant spreadsheets/data. Cable Connections 4 DEMA ELECTRO MAGNETIC APPLICATIONS, INC Route the Inner Conductor Connections Based on Block Diagram Connection number Connection type (T=TSP) Take each connection and trace through block diagram segments Gauge Number of wires TSPs, etc. 5 DEMA ELECTRO MAGNETIC APPLICATIONS, INC Compiling Parameters 6 DEMA ELECTRO MAGNETIC APPLICATIONS, INC Compiling Parameters 7 DEMA ELECTRO MAGNETIC APPLICATIONS, INC Probes – Pin Transients For 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. 8 DEMA Running the Wizard ELECTRO MAGNETIC APPLICATIONS, INC DEMA ELECTRO MAGNETIC APPLICATIONS, INC 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. 10 DEMA ELECTRO MAGNETIC APPLICATIONS, INC Check Orientation of Lines CADfix Command Ploc sens on Arrow goes from end 1 to end 2 To change orientation Orev linename Once this is completed then put all geometry into a mesh set and mesh 11 DEMA ELECTRO MAGNETIC APPLICATIONS, INC Start the MHARNESS V4 Wizard 12 DEMA ELECTRO MAGNETIC APPLICATIONS, INC MHARNESS Wizard Filename and Time Step value and number are populated automatic ally but user can modify Select level of shielding – in this case we have TSP shielding and an overbraid so we have two levels of shielding. 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. 13 DEMA ELECTRO MAGNETIC APPLICATIONS, INC 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. 14 DEMA ELECTRO MAGNETIC APPLICATIONS, INC MHARNESS Wizard Next the Wizard will highlight each segment in the CAD and request input Input Segment Name 1 mm default End 1 and End 2 names (Slide 11) Note enter 0 for terminations 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. 15 DEMA ELECTRO MAGNETIC APPLICATIONS, INC MHARNESS Wizard After input each segment, you will be asked to input the total number of level 1 (in our case TSP) cables. 16 DEMA ELECTRO MAGNETIC APPLICATIONS, INC MHARNESS Wizard Now you will be asked to route each TSP cable. You should have the preparation material handy to help keep track of the cables. 17 DEMA ELECTRO MAGNETIC APPLICATIONS, INC 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 18 DEMA ELECTRO MAGNETIC APPLICATIONS, INC MHARNESS Wizard Next 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 19 DEMA ELECTRO MAGNETIC APPLICATIONS, INC MHARNESS Wizard Then 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. 20 DEMA ELECTRO MAGNETIC APPLICATIONS, INC 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). 21 DEMA ELECTRO MAGNETIC APPLICATIONS, INC MHARNESS Wizard undo Make shield larger or smaller Navigate back and forth between segments 22 DEMA ELECTRO MAGNETIC APPLICATIONS, INC Additional Cable Pack Features Visualize existing MHARNESS file (beta) Zoom view Output file when done 23 DEMA ELECTRO MAGNETIC APPLICATIONS, INC 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. 24 DEMA ELECTRO MAGNETIC APPLICATIONS, INC 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. 25 DEMA ELECTRO MAGNETIC APPLICATIONS, INC MHARNESS Wizard After 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 26 DEMA ELECTRO MAGNETIC APPLICATIONS, INC MHARNESS Wizard 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). Depiction of Shield (Overbraid) and TSPs Connector Conductance Boundary Condition Connector Conductance Boundary Condition Boundary Condition Connector Conductance Boundary Condition Connector Conductance 27 DEMA ELECTRO MAGNETIC APPLICATIONS, INC MHARNESS Wizard Enter the number of probes: 28 DEMA ELECTRO MAGNETIC APPLICATIONS, INC MHARNESS Wizard 29 DEMA ELECTRO MAGNETIC APPLICATIONS, INC MHARNESS Wizard And create your .inp file! 30
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