How to get 480vac 3-phase

[400bird]

I'm considering picking up a lather that is set up for 480 3-phase.

I was hoping to find a VFD that would convert 240 split phase straight to 480 3-phase. I haven't found one yet (at least one that is reasonable)

What would you recommend to get about 5kw at 480 3-phase?

The options I can think of are:
Transformer to get from 240 split phase to 480 single phase, then VFD to get 3 phase.

Battery inverter to get from 48 volts DC to 480 3-phase. I might still run a VFD to get speed control.

Digital or rotary phase converter.

 

[timselectric]

Battery inverter to get from 48 volts DC to 480 3-phase.

Probably the most efficient option.
And you can turn it off, when not needed.

 

[pvdude]

Any reason you could not use a VFD?
Here is an example:

 

[Hedges]

No VFD boosts voltage.
Step-up transformer could work. With ripple, can't power as much as 3-phase in.

I have single phase "120V" grid --> SI master, 3-phase cluster makes 125V/120V/120V
Transformer step-up to about 480V Y for Sunny TriPower

What do you want 480V for? Many motors can be rewired for a second voltage (Y vs. delta) and some more than two.

 

[400bird]

Any reason you could not use a VFD?
Here is an example:

I'd love to, but I haven't found one yet. That one listed has the same input and output voltage. The machine name plate is 440 3-phase and I have 240 split phase at the house.

No VFD boosts voltage.

Bummer, I was hoping to find one that would.

Step-up transformer could work. With ripple, can't power as much as 3-phase in.

I have single phase "120V" grid --> SI master, 3-phase cluster makes 125V/120V/120V
Transformer step-up to about 480V Y for Sunny TriPower

Interesting, I'd love to hear more. Well, an idiot's guide to more

What do you want 480V for? Many motors can be rewired for a second voltage (Y vs. delta) and some more than two.

Mill, lathe, surface grinder, and drill press.
I don't need to run them all at once and the drill presses would just be to test them and let them move on to a new home.

I was hoping to rewire down to 240(ish) 3-phase, but I can't find a tag on the motor saying that is possible and I can't pull the junction box covers until I own them. This would be my preferred option, but I'm just trying to get an idea how expensive and complex this is going to be.

Probably the most efficient option.
And you can turn it off, when not needed.

I'm not running a production shop, just another hobby, so efficiency isn't high on my list.
I can cut the breaker on the other options too.
But a battery inverter sounds easiest by far, but likely expensive. I'm not having much luck finding anything other than $6000 MPPT Solar level options.

 

[Hedges]

3-Phase SMA Sunny Island (15kW) + Sunny TriPower (30kW)

Showing a work-in-progress assembling 3-phase SMA system. 3x SI-5048-US are configured for 3-phase and produce 120/208Y, rated 15 kW continuous. Sunny TriPower 30000TL-US-10 is 480V delta (or 277/480Y), rated 30 kW. TriPower combiner box will be used, but for now just one string being connected...

diysolarforum.com

Transformers aren't well behaved, and aren't "ideal".
You may or may not get away with running a step-down transformer in reverse with grid input. Likely not with inverter input.
Even running its intended primary at rated voltage, it will draw excessive reactive VA. My solution is to run below rating, often 50% of rated voltage.
I rewired (probably described in the thread) delta input as Wye and put 120V into 230V tap, used as auto-transformer, left centertap disconnected from driving inverters. Then it settled down.

What worked better was 3x single-phase transformers wired as auto-transformer run at reduced voltage.

Motors likely have delta vs. wye winding option, e.g. 277/408Y could be changed to 277 delta, reasonable for 240 delta.
3-phase motors will run fine well below rating. I think the 2hp motor I put on air compressor was initially wired for 440V and it started & ran fine on 208V. Might have even run the compressor that way? But I rewired for 208-220 input.

With 240V VFD you should be able to start and run the 440V 3-phase motors, just have reduced torque due to reduced current. Maybe avoid a VFD able to send more current than it can take, or better yet put in breakers. I had cooked the split-phase compressor motor, stalled until overtemp switch opened. Now have magnetic-hydraulic breaker which I think will trip faster.

Or use a step-up transformer (maybe the right taps to get 440V) and 480V VFD.

 

[timselectric]

Yeah
Best that I can come up with would be around $4k.
Not including a VFD.

 

[Hedges]

Small VFD $200 to $500.
Old utility transformer repurposed for split-phase step-up $500 +/-

How big are your motors?

VFD isn't to power the shop, just a single motor.
5kVA VFD is bigger. My 2HP is 1.5 kVA, the largest from Hitachi that recommended split-phase input.
I've seen higher power Chinese brands that said single phase input OK.

Cheap 220V

Single To 3 Phase 7.5KW 10HP 220V Variable Frequency Drive Inverter CNC VFD VSD | eBay

The input for this VFD is 1 phase. There is enough space for cooling between each component, and the product casing is designed with multiple holes, the above features can make this VFD have a longer service life.

www.ebay.com

480V

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Find many great new & used options and get the best deals for PREOWNED - Delta Electronics 3-Phase Inverter VFD037E43A 5Hp 0-480V 8.5A 6.8KVA at the best online prices at eBay! Free shipping for many products!

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[400bird]

I did some hunting and the lathe main motor is 7.5 hp, the problem is that there's likely a second motor
The machine is only labeled at 460vac, but there are a couple threads online of people converting everything over to 240

The lathe is a Leblond Makino Servo Shift Engine Lathe.

There's also a mill, but if that's 480, it should be easy enough to swap the wiring to get it running on 240. There's only one motor.