Digital three phase converter

[SnakeyJ]

I run a small static converter for my lathe and cutter grinder, but was recently looking to build a rotary converter to supply multiple machines (4-5kw/7.5HP).

However, having been put off by startup current requirements, I came across these digital 3 phase converters (1P 240V to 3P 415V). These are about a third of the price of a similarly rated commercial RPC and much smaller footprint and peak load. Unlike a VFD, they claim to provide full 3P output for multiple machines.

3 phase digital converter 4kw 5.5hp, input 240 volt 1 phase output 415 3 phase | eBay

4Kw / 5.5Hp 240 Volt Digital Phase Converter. ( Converter in Picture is a 5.5kw this add is for a 4kw). Output Volts 415 Volt 3 Phase ( No Neutral ).

www.ebay.co.uk

Does anyone have any experience or offer any advise on these?

 

[matthewsx]

I run a small static converter for my lathe and cutter grinder, but was recently looking to build a rotary converter to supply multiple machines (4-5kw/7.5HP).

However, having been put off by startup current requirements, I came across these digital 3 phase converters (1P 240V to 3P 415V). These are about a third of the price of a similarly rated commercial RPC and much smaller footprint and peak load. Unlike a VFD, they claim to provide full 3P output for multiple machines.

3 phase digital converter 4kw 5.5hp, input 240 volt 1 phase output 415 3 phase | eBay

4Kw / 5.5Hp 240 Volt Digital Phase Converter. ( Converter in Picture is a 5.5kw this add is for a 4kw). Output Volts 415 Volt 3 Phase ( No Neutral ).

www.ebay.co.uk

Does anyone have any experience or offer any advise on these?

Do your machines run on 415v?

I think we’ve discussed these devices here before but I don’t remember the details. I doubt it’ll be satisfying for running multiple machines.

I’d try to find a commercial supplier rather than an eBay seller for more details on the specific unit in question, there didn’t seem to be much detail on the listing.

John

 

[mksj]

Typically they are not plug and play for multiple machines, and most transformers/electrics will not be happy running on VFD generated power. People have used VFD's as a fixed frequency power source for multiple machines, but in general it is in fixed V/Hz mode, the VFD needs to be significantly oversized (like 4- 5X), and you loose the overload protection features. I would verify with the seller what they mean by Plug and Play, if it is for multiple machines and the rating for each machine. There have been posts over at the Practical Machinist similar to what you are proposing, it did work for one UK machinist but he did not indicate any details. The other factor to consider is many of these generic Chinese VFD's are overrated as to their output and also have a high failure rate in particular with high loads.

 

[SnakeyJ]

Thanks @mksj and @matthewsx for your responses, I will contact the seller and ask for more info, though I am increasingly sceptical.
I did do a little more searching last night, but can't find similar units or claims from the more established vendors.

My lathe (Colchester Bantam) has a dual speed motor that requires 415v 3P. It does run on a transwave static converter, but it is a bit fussy at high speed and when running the suds pump. Lots of boost required to start, but I have to click this down when running to avoid overheating on the motors.

My Clarkson grinder is three phase, with a 0.5hp ASEA motor. This can be wired to run 220v delta or 415 star. My STC is rated for a minimum load of 0.75hp, but does run this and the motor does not seem to warm up.

My Mill also has a bigger ASEA motor, but is currently run at 220V delta from a cheap VFD. I will probably keep this on VFD as it gives higher speeds and the ability to reverse for threads.

I will upsize on the lathe, to a Harrison M300 or more recent Colchester Student, but no real urgency. I would like the option to run 3 phase TIG/MIG inverters and probably a small surface grinder as I upsize the workshop.

 

[matthewsx]

Sounds like building/buying a rotary converter would be best for you, but more research is always good.

Not sure how to approach the issue of having multiple voltages, we see a lot of 480 3ph here in the states but I’m not familiar with 415v.

Good stable power is a must so getting this right is critical. Let us know what you learn.

John