VFD Advice

[Steve355Participant @steve355]

Hi

looks like I got myself a new toy on eBay (surface grinder) but it’s 3 phase and I only have a standard 240v mains supply. I’ve been looking into VFDs but it seems complicated,

Could somebody knowledgeable please tell me what a suitable 3 phase conversion device might be. I’ve tried to get a pic of the motor plate but it’s in the most awkward place. Hopefully its readable.

thanks

Steve

[Steve355Participant @steve355]

[peak4Participant @peak4]

As you've already spotted, the issue is that it's a single voltage motor, which precludes the use of the cheapest Chinese inverters, but there are other solutions.

The motor can likely be re-connected internally to allow delta, rather star winding, to allow for the cheaper inverters.
I believe some firms who supply inverters, such as Newton Tesla, will assist with that so long as you buy the inverter from them.

You can get static and rotary 3 phase converters, from such as Transwave, but they might be a bit over the top pricewise for a single machine. Machine Mart used to do a cheaper one.

Many UK based inverter suppliers now offer a 240v in – 415v 3 phase out inverter/VFD, though they are more expensive than the 240v in – 240v out ones, but they seem to have vanished off ebay of late. I think you need an AT3 type for the higher voltage output. Again Newton Tesla, or maybe Inverter Supermarket.

Premier Machine Tools also offer a suitable package, though I've not used them myself.

Plenty of options there, without needing to replace the motor; I'm sure others will be along soon to chip in.

Bill

Edited By peak4 on 24/07/2022 22:38:16

[Thor 🇳🇴Participant @thor]

Hi Steve,

From the nameplate it seems like a 400V motor, it may be possible to open up the motor and re-connect it for 230V as Bill says. Is it possible to replace the motor with a newer one that can be connected either star or delta so you could use a cheap VFD? There are solutions that provide 3-phase 400V out from single phase 230V, one example here.

Thor

[not done it yetParticipant @notdoneityet]

Looks like it is either a Hammond or an Eagle.

Guessing it must be the Hammond – because a simple search on the forum would have provided oodles of info on the Eagle.

Go on, don’t be so secretive with the details. Which machine is it?

[Steve355Participant @steve355]

Posted by not done it yet on 25/07/2022 06:16:10:

Looks like it is either a Hammond or an Eagle.

Guessing it must be the Hammond – because a simple search on the forum would have provided oodles of info on the Eagle.

Go on, don’t be so secretive with the details. Which machine is it?

its the Eagle. I didn’t think to search the forum on VFDs for the Eagle.

Well I got it from Wales to Herts, now the really hard bit of getting it out of the car and into the shed.

[Steve355Participant @steve355]

Posted by Thor 🇳🇴 on 25/07/2022 05:49:20:

Hi Steve,

There are solutions that provide 3-phase 400V out from single phase 230V, one example here.

Thor

Great idea, I just picked up a “new/other” one – 2hp version, on eBay for £80.

Problem solved – hopefully! Thanks!

Steve

[Robert Atkinson 2Participant @robertatkinson2]

That converter should get you running.

Note however that they don't produce a proper 3 phase supply. They can cause quite a bit of torque ripple from the motor. This in turn causes vibration, not a good thing with a surface grinder. So if you are getting vibration or poor surface finsh don't automatically blame the mechanical bits.

Robert G8RPI.

[Author]

Posts