Since it's the math-and-meta channel, the formula for power usage in any machine is; [Located directly on the wiki under Power Amplification or Clock speed]
MW Usage = DefaultMW x AmplifiedMW x (Clockspeed/100)^log_2(2.5)
Where:
DefaultMW - the standard, 100% clockspeed power draw of the machine you wish to calculate (4MW Constructor, 15MW Assembler, etc)
AmplifiedMW - The effects of somersloop boosting the machines output on power consumption. This has the formula (1 + SlotsFilled/Total slots)^2 (A constructor has 1 slot for 1 sloop total, Assembler has 2 somersloop slots, Manufacturer 4, etc)
Clockspeed - Fairly self explanatory, the clockspeed you desire to set the machine to.
You don't have to use log_2(2.5), it's common to just say its rounded down form of 1.321928, but it refers to needing 2.5x more power to double the output of the machine (200% clockspeed).
So in your case, A single machine (constructor 4MW, assembler 15MW, manufacturer 50MW) clocked to 150% equals approx. 6.84MW, 25.64MW, 85.46MW respectively.
Having 1 machine set to 100%, one to 50% = 5.6MW, 21MW, 70MW respectively.
Having 2 machines set to 75% = 5.47MW, 20.51MW, 68.37MW respectively.
Having 150 Machines set to 1% = 1.36MW, 5.11MW, 17MW respectively. Extreme case, but if you are concerned on power, I suppose you could do this... for some reason..
When you get to machines that have power fluctuations, some power like having their consumption graphs 'relatively flat' just for personal reasons, so they may underclock the machines a long way in that regard, or for the sake of logistics, whichever prevails
tldr; Power consumption is not Linear. The amount of MW difference is really negligible until you start getting in to manufacturers and beyond, and even so by the time you get to that point the easiest solution is just build a power grid that is big enough to support whatever you desire. I'd recommend designing factories that tailor towards simple logistics, rather than power consumption 🙂