In that TO thread we arrived at the conclusion about unavailability of critical details about the data/spec numbers that are needed to validate the claim of lossless HEP, which in the face of it would be just one step short of having a Flux Capacitor.
The question about "lossless relative to what" cannot be answered given the available information because the rated HP number details are apparently trade secrets. We do not know at which point is the 4400HP speced. At the driveshaft of the prime mover? On the DC bus? At the wheels? When these specific questions are asked they are not answered in a straightforward way either by Siemens or any of the users of those units.
One thing we can rest assured is that no laws of Physics or Mathematics have been broken. Good marketing obfuscation OTOH is the most likely explanation, and at some point we may be able to figure out the details if an appropriate leak can be discovered somewhere