How do you guys typically model PDUs? Do you model each component like an individual component? do you model the wiring in-between?

For example, a recent project includes an IT floor with CRACs, PDUs, and server equipment. A typical trunk might include a distribution panel feeding a number of PDUs, which comprise a 480V, 200A breaker>few feet of conductor>transformer>two "panel" main 225A breakers>misc. branch circuit breakers, including one 3-pole 100a breaker which feeds a subsequent panel 20'-150' away.

I'm inclined to model each component, however the PDU transformers have no impedance numbers on their nameplates. I know transformers of that size typically range from 2-5%, but I've also heard that PDU transformers tend to have lower impedances.

Do you guys typically model every component or treat them as a single component?

Every component...

Mike

Every component. I've not seen a PDU with isolation so you'll likely label with the worst case IE and the highest voltage.

Thanks, guys. So question: What do you consider an appropriate estimation for impedance? Despite being a well-known brand of PDU, the transformers do not list impedance. I'm hesitant to estimate for impedance because it has such an outsized effect on incident energy.

Here's an example photo of what I'm talking about.

What I've done in these cases is either:
1) Ask the customer for a submittal. If that is a dead end;
2) Assume an impedance and document that in the report. There are a number of references for impedance estimates you can use for dry types.


Mike