I've been running a 10 HP (nominal) "whole shop" 240 – 415 V system for the last 10 years or thereabouts without problems. Obtained used with, I think, a couple or three years of full time use under its belt.

Using the machine controls to start-up with the inverter already running at 50 Hz rather than using the inverter controls with the inherent soft start does stress things a bit more but so far so good. Main point with the whole shop deal is to stay within the inverter design short term overload capacity. Basically don't try to start a motor of power more than half the inverter rating. Don't start a motor under load. Personally I'd derate further to 1/3 rd nominal power but accept things like directly coupled lathe spindles and bandsaw blades. My largest motor is 3 HP so thats what I do. The one on the Pratt & Whitney lathe is a two speed one too. Its not abuse unless you go too far in power demand. By the very nature of things any decent inverter has to be designed with significant short term over current capability before the DC voltage inside drops too far for proper operation.

If you are running it on a single machine using the inverters own controls things are a lot more relaxed but ultimately the voltage doubling modifications do reduce the overload capability and, probably, maximum power output. If your machine is to be run flat out at full power derating the inverter a bit is probably a good idea. In practice derating comes automatically for most home shop types. We don't like to run our machines factory hard. If nothing else the chip blizzard at full chat is unpleasant.

Clive

Yes, mine was from Drives Direct. Via eBay at first until I realised that I'd managed to buy completely the wrong unit. Dur. They were very helpful and after I'd returned the unit and paid some more money they shipped the right one…

My 3HP converter is running a 3HP motor…

One thing I'd like to add is a load reactor – there is quite a lot of high frequency noise from the motor, and it heats up quite quickly too. This isn't a criticism of the Drives Direct unit – it's common to all VFDs…

I also (same caveat as above) had to add some filtering to the single phase input 'cause funny things started happening to our fridge / freezer when I used the mill!

HTH…

Jez.

Seems have same Plug and Play 7.5KW inverter Clive brand new £900, seen the price as of last year close on £2k.
Mine if I can get lathe spindle to run just about powers a 3hp motor so would say triple motor capacity for startup purposes no soft start contactors chatter in and out as voltage ups on initial power up.

Same with Transwave rotary 5.5HP convertor kept as backup, spindle slows at anything more than a cleanup cut.
For the short time I had it 1hr 25mins a 4KW 240v to 400V 3ph had similar issues with loading though not half as bad as Transwave at fairly close output power and price.

Not many know about the voltage doublers.