Hallo,

I've discovered a phenomen which I claim to be a fatal PSpice error, at least something that I don't understand at all.

Try simulate the following netlist

- source 3_029_B01_TLINEVERIFICATION V_V_DC N00124 0 2 R_R_DC N00124 C1 52 X_T_DC C1 0 0 0 FIM02YHBY PARAMS: LEN=100 R_R_TRAN N00504 C2 52 V_V_TRAN N00504 0

To clarify the whole thing. I have two lines of 100m each. Each line is shorted at the end and fed via a 2V and 52R resistance. C1 and C2 are the nodes at the input of the lines.

The subcircuit of the transmission line is

***FIM02YHBY is a shielded twisted pair from Gebauer&Griller ***The shield is not modelled as conductor but its influence on

***the line parameters is accounted. ***Model parameter derived by measurement and calculation. Refer to

***document 3-029-B01-D001 for details. ***6.283 is an approximation of 2

***Pi ***Both resistors prevent a node floating error.

***----------- ***Pin Desc

***10 Near end high ***20 Near end low

***30 Far end high ***40 Far end low .subckt FIM02YHBY NH NL FH FL PARAMS: LEN=1 T NH NL FH FL T1 R1 NH FH {1/GMIN} R2 NL FL {1/GMIN} .model T1 TRN( +r={342m+0*sqrt(s/6.283)} +l=493.17n +g={0*(s/6.283)} +c=45.216p

- LEN={LEN}) .ends

To my model, skin effect and dielectric losses are prepared but yet not considered, therefor the 0 in the formulas. All other values I have measured on a real piece of cable very carefully.

Now make a transient simulation to t=1m. After this time the transient has settled down to its final state. So the voltage on node C1 and C2 should be the same, cause it is simply a voltage divider from the DC losses of the line and the source resistors of 52 Ohms. But my simulation shows a big difference. C1 is at 793mV which is the correct value assuming that the line has 100m length and 342mOhm per meter. C2 is at 1.05V which leads to a DC resistance of 574mOhm per meter.

So what's the story? Why shows the same trasnmission line a DC resistance of 342mOhm per meter and 574mOhm per meter?

I'm really looking forward to any good explanations, because this shatters any confidence in the reliability of PSpice.

By the way: I'm running OrCAD Pspice 10.0

Best regards

Oliver Friedrich