Hey Robert,
it is important to understand that for a specific amount of power (watts), on a lower voltage (volts), there need to flow more current (ampères).
A 2.2 kW VFD for 230 V (I have one) is rated with 24 A input current on single phase input. For the same 2.2 kW VFD, but on 120 V, you would need the double current on your circuit dimensioning (48 A), but it would still be the same power. Therefore, the more your device consumes, the better it is to choose the variant for a higher voltage. This is because the wire gauge needed, and the fuse (circuit breaker) dimensioning are not dependent on the power, but on the current.
So when running a device that has a lot of power on 120 V means higher current than you usually have at your circuit breaker, with the same power at 240 V you have half the current, half the ampères on the circuit breaker and half the thickness of the wires needed, so that’s why you usually better choose the higher voltage.
That is also the reason why the electricity that has to be sent over large distances is transformed into very high voltage: The higher the voltage, the lower the current (for the same power), and the less the effect of the wire resistance, and thus the less the power loss over the distance.
that’s what I meant in the other thread (here and here). I know that despite the fact that it is usually not recommendable to buy equipment for which you have no appropriate electrical supply circuit, many people (be it that they did not know it better) bought those 2.2 kW 110 V VFD/spindle kits and run them on thin cables and mingy fuses and I think many would not even think about it because they don’t use their machine in a way that they even come close to the power limits. The difference if you DO consider the things I tried to explain would be that you know that your equipment can draw more current than your circuit can deliver, and that you can decide to use it anyway, you would limit the current inside the VFD so that it would rather be the VFD that trips in case of higher mechanical load when milling, than your fuse (circuit breaker), because with a good safety wiring you can make that when the VFD trips the Onefinity Controller gets the pin 23 activated so the stepper motors stop to move immediately and your bit is saved, instead of a VFD whose circuit breaker tripped and a Onefinity CNC continuing to run and breaking your bit.
Also you can perfectly limit the current delivered to the spindle inside the VFD, you even got to do that anyway since it’s one of the first settings you do when you set it up.
PS: @Echd: I assumed you measure this on the input side of the VFD, between wall outlet and VFD, is this correct?