Using a small, cheap inverter for single to 3 phase

[RobWard]

Hi.
We've just bought a small linisher.
It's 1.5kW 3-phase.
I've seen some very cheap inverters (<£100) that we could use to power it from a single phase supply, which would actually be cheaper than running a 3 phase supply to where we'd like to site it.
I've read some old threads here about going from single phase to three phase.
The advice was to use something with twice the capacity, so a 3kw inverter would do nicely.
(It's very intermittent use so I don't have a problem running it off a 13A supply)
My question is - is it worth it? Are cheapo inverters any good or am I asking for trouble, and are there any features that I should be looking for when buying one?

Many thanks for any advice.

Rob

"I love deadlines. I love the whooshing noise they make as they go past." Douglas Adams

 

[btrueblood]

We did this for a machine that needed a variable speed pump, usable at UK and US voltages. Solution was a simple 1/2 hp 3 phase motor, driven by an inverter VFD, which drew power from US mains directly, or via UK/European mains via a 2:1 step down transformer. The whole setup was reasonably cheap, and if I recall, the VFD was about the same cost as the 3-phase motor.

 

[itsmoked]

In your case I'd certainly toss in an over-sized VFD and run that motor with it. If you only run it intermittently and it's the type of device you load for a few seconds with unloaded periods while you re-situate the work piece and run more load you don't even need a 2X VFD.

Check the actual FLA of the motor and get a VFD with 50% more output. Lately I've seen surprisingly high output currents available on VFDs based on HP. Example would be say a 2HP VFD that you'd expect to output a typical 2HP motor's FLA but the VFD rating ends up offering 35% more output current than the typical 2HP FLA.

Ebay would do it cheaply.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[RobWard]

Thanks for that. It sounds like it's worth a punt.
It'll be interesting to try, at least.
I'll try to let you know how I get on.

"I love deadlines. I love the whooshing noise they make as they go past." Douglas Adams

 

[jraef]

Most VFD mfrs offer a version up to 3HP (2.2kW) 240V that are pre-designed for a single phase input, meaning no doubling of the HP is necessary. They are all inexpensive.

Beware of impossibly low pricing, there is always a reason. I am of the opinion that you can get very good name-brand products at very reasonable costs, but if you go for the lowest cost “no name” drives from China sold only through on-line sources, you will be exposing yourself to the risk of getting some real junk. Also, beware of used drives, also sometimes impossibly cheap. If a drive sits on a shelf unpowered for 2 years or more, they need specialized attention to avoid being damaged just by applying power to them. You have no way of knowing how long a used drive has been sitting around.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[RobWard]

A quick update.
Taking jraef's advice I thought I'd pay a little more but source from some reputable resellers rather than ebay.
With such a variety on offer on various websites I emailed several to seek their advice.
The first declined to quote, the others haven't responded, which is a little disappointing.
I'll have to take a stab at it myself.
I'll try to let you know how I get on.

"I love deadlines. I love the whooshing noise they make as they go past." Douglas Adams

 

[LionelHutz]

Try a site like automationdirect.com.

 

[itsmoked]

Those dealers don't want any of the liability that comes with them helping a DIYer type, so I wouldn't expect any response.

Note the smaller drives

Actually, I have an old NEW drive you can have. Pay for the shipping and it's yours with caveats. I have never powered it up. You would definitely need to re-form the capacitors by powering it up for 24 hours before ever loading it in any way. There is a small but finite chance the caps would pop. If they don't it would work for you.

Oh damn.. Great Britain! Maybe not worth the hassle.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[RobWard]

That's extremely kind Keith, but it's probably easier to source one locally.
I might speak to Parker drives as I've used a few of theirs in the past successfully, just not going from single phase to three phase.
If they can confirm which model I need then I can order one fairly easily.
It's disappointing when you are just asking a supplier to verify that you've selected the appropriate drive from their stocklist, or if they can explain the difference between different manufacturers that they stock, which their websites don't reallly do, and they haven't replied. What's the point in having a sales enquiry email address if they don't use it?
At least people have been kind enough to reply to this thread with helpful advice (and offers!) Thanks everyone!

"I love deadlines. I love the whooshing noise they make as they go past." Douglas Adams

 

[JohnMcNutt]

I don't know about other brands, but the general advice on here has been to use one from a big name mfr.

Hitachi makes single-phase-intended units, and we have one and it has been performing well.

https://hitachiacdrive.com/hitachi-nes1-series-ac-drives/

 

[jraef]

A good brand sold mainly in the UK is Invertek.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[RobWard]

Just an update:
I contacted Parker drives who told us exactly what we needed.
We spent a little more than I had anticipated as we went for one in an IP66 enclosure to save faffing around sorting that out seperately.
The technical help was terrific - it's been a long time since I messed around with an inverter but they gave me all the instructions I needed to set the correct parameters.
The whole thing took a little longer than I planned because I couldn't dedicate much time to it without being broken off and it was one of those mchines that are a pain to take apart - to get to the motor just to check the wiring meant disassembling half the machine.
Anyway after a few hours of actual work the drive is mounted nicely, all the original gubbins and wiring is still there, neatly labelelled so that we can undo the conversion simply if needed, and the drive operates from the original switches so it all looks neat.
Thanks for all the advice offered - I'm glad I didn't go out and buy a cheapo drive from an auction site - it would have cost more in the long run building an enclosure and then spending a long time sorting out the wiring and programming, I'm sure.
Thanks again everyone!

"I love deadlines. I love the whooshing noise they make as they go past." Douglas Adams

 

[itsmoked]

Yes that was probably the right move. I'm this moment assembling a 460V 30hp control panel with a chiller controller and a few pneumatic operators to open the lid on a mixer. The mixer is two blades with 1 foot radius. The two top blade tips bent up the other 90 degree away are bent down. How the heck those 1/2" thick blades are going to absorb 30hp is beyond me... Anyway what a PITA assembling all that.

Keith Cress
kcress -

http://www.flaminsystems.com