Does the MV to LV transformer output 128 EU/t, or does it require four transformers to use the full energy from a diesel generator or an advanced steam turbine?

With overclocking upgrades, the energy requirements can be higher than the power of a steam turbine. So using an advanced steam turbine with a transformer would give more energy units for overclocked machines.

I realize that an LV machine can be upgraded to use MV energy units.

The only thing tiers do is limit the total amount of EU/t in cable networks. Everything has unlimited input/output rates (well, actually the max rate is what can fit in their energy buffer). Hopefully you can figure it out with this information.

Thanks, not quite sure what you mean. I've noticed that the cables don't limit the EU/t to the machine, otherwise the machines could not be overclocked, the centrifuge is an example. I'll see if I can figure it out. Many thanks.