I am looking at buying a new lathe either new or used. Most have motors 4 to 5 hp, frequently 2 speed motors. I read somewhere that you could derate a 3ph input VFD so that you could use single phase. I was wondering if anyone has experience with this and specifically if the Hitachi WJ200 110LF would work with 4 or 5 hp motors if I used single phase input instead of 3?

http://www.clrwtr.com/Hitachi-WJ200.htm

Any other suggestions would be appreciated.

My lathe and two post lift were both 3 phase, just replaced the motors with single phase.

I did put on larger motors, very cost effective compared to expensive boxes!

Not sure on this specific drive, a couple of pointers

I'm making the assumption that your supply is uk single phase 220v ac

You can run a 3 phase motor from a VSD powered by single phase, but the maximum output voltage will be nominally the same as the input voltage
ie Single phase 220v in 3 phase 220v out

So to spec a drive....
Confirm that the 3 phase motor can be connected/powered by 220v 3 phase
Find out the full load amps FLA of the motor when connected to 220V - this should be on the motor nameplate

Select a suitable single to 3 phase drive based on the motor FLA

The Hitachi manual from you link is showing the largest single phase supplied drive is for a 3HP 220v 3 phase motor for lathe type applications
I couldn't find the supply current for this drive, but they do call for 30A fusing

I had a quick look at Allen Bradley PowerFlex 525 (I used to work for them) their specs are almost identical


edit, I just re-read your original post, you mentioned the 110LF which is 220v 3 phase 22hp

The only mention I could find in the manual was...

"TIP: If your application only has single phase power available, refer to WJ200 inverter
of 3HP or less (European version with a suffix of -SFE); they can accept single phase
input power. Note: Larger models may be able to accept single-phase with derating.
Contact your Hitachi distributor for assistance. "

My gut feeling would be that even if this drive could be ran off a single phase, it would be far to large for a domestic supply
The specs show that it would normally be protected by 80A fuses
Typically the input supply has to be able to support the drive rating even if it's used with a smaller motor, this is because the drives have a large inrush of current on power up as the capacitors charge

As Mark said above, a swap to a single phase motor may be the best choice

[Edited on 12/11/16 by Toys2]

I made a voltage doubler to turn single phase mains to 600V DC.
Then connect to the VFD internal DC bus.
To prevent the surge current blowing fuses, I bought a current inrush limiter component from farnell.
I put a relay circuit to bypasss the current limiter after turn on, to reduce heating of limiter device.

Working fine for the past few years on a homemade CNC mill, up to 1.5KW.

Darren