Quote Originally Posted by John S View Post
The VSX-75 is a 1 Hp model inverter and takes 7.2 amps with single phase input.

The next one up in the range is the 150 or 1.5 Kw which will run a 2 Hp motor and that requires 14 amp.

The later updated VXSM's take 10 amp and 16 amps respectively

The cheaper Mini series takes 6 amps and 10 amps respectively.

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thanks for that info John.. my motor is rated on the plate as 1.5HP but seems to work OK on that VFD, it doesnt even get hot (I do have a small fan on the heatsink but it really doesnt need it)... maybe for the lathe its OK as its not running for any significant time and the load is minimal (I cant do big cuts its not that rigid). the motor I have for the mill is 1HP and a fairly recent one (<10y old). Not fitted yet as I need to make some brackets.

The manual for the VSX-75 says it needs to be on a supply with a 16A surge rating and it did used to trip the 10A MCB on start (not every time tho) which is why its now on a 20A MCB (although a 15A would probably be correct except I couldnt find one at the time). Maybe it would work on a 13A plugtop but I reckon there be a few replacement fuses needed from time to time.

Incidentally there some useful info here on cable and MCB selection which shows, for example, that the 1.5mm 4 core cable sold by B&Q as central heating control cable is fine for a 1HP 3phase motor wiring up to 15m (not that you'd want to run that far anyway) - my VFD manual talks about 4mm cable (which is impossible to buy in short lengths!)