220V single phase to 380V three phase

**JohnHaine** · 18-04-2023

Hard to say if it would stall at the lower speed, that's more a function of torque than power. Just change the pulley ratio surely? But you can vary the speed with the VFD of course.

Ideally you need 3 core screened cable. The current won't be particular high so anything rated at 5A per core would be fine I'd guess. There is debate about how to connect the screen but for RF the screen should be firmly grounded to the E terminal of the VFD at one end and to the motor casing at the other. If you can't get 3 core screened then electrical suppliers sell 4 core cable for 3 phase one of the cores being for a ground.

**m_c** · 19-04-2023

Personally I'd probably wire it for low speed, then overspeed it via the VFD.

You could wire it for highspeed then run it slower from the VFD, but you won't get as much torque at the lower speeds.
From the plate details
0.45KW at 2800rpm is 1.53Nm
0.3KW at 1400RPM is 2.05Nm

Using the high speed windings, you'll have 1.53Nm from 2800rpm down to probably a few hundred RPM. This depends on VFD ability, motor performance, but it'll reach a point where the motor will noticeably lose performance and likely become noticeably rough.

Using the low speed winding, you'll have 2.05Nm from low speed to 1400RPM. Due to the lower rated speed (the two speed essentially works by selecting 2 or 4 pole operation), the motor will also be capable of being spun slower before performance becomes an issue.
From 1400RPM to 2800RPM, the power output will remain limited at 0.3KW which means the torque will gradually reduce from 2.05Nm at 1400RPM down to 1.02Nm at 2800rpm.

However, if your main use was in the higher speed range, then wiring it for the higher speed range would make more sense to get the most power.
Off course, you could add a changeover switch, but you'd have to ensure you don't switch it with the motor powered and spinning.

**mekanik** · 20-04-2023

mc

Thanks for taking the time to reply and your power calculations.

I contacted motorsandinverters and quized them about the 380V on the motor plate and they said a 220V inverter drive would not work with the motor, they offered a static converter @ £1100+VAT and said that would do but from what i understand as static converter supplies 2 phases, and the proper way to do it is with a rotary converter. so back to square one.

If i took some readings of the original single phase motor would you be able to determin which of the coils is damaged, and if the low speed coils are OK i could disconnect the high speed coils from the switch.

The motor actually run OK it was just the fact that it was getting hot that made me investigate.

**JohnHaine** · 20-04-2023

Ask Inverter Drive Supermarket. They have a (rather poorly written) application note on 230v running. The people you spoke to want to sell you a static converter. They also have 230v 1-phase to 380v 3-phase units. "Static" converters are yesterday's technology. (Actually a VFD is "static" but generates proper 3-phase.)

**mekanik** · 20-04-2023

Thanks for that John
I had seen 230V to 380V three phase VFD's advertised, just as well i came in for brew i was about to swop the motor covers and rotors again and commence on a box to send the single phase motor for a very expensive rewind.
was on a forum yesterday and some guy in the US added a stepup transformer before the inverter then bought a 440V to 440V VFD apparently that worked and i have seen another US made inverter that does the conversion from 220V to 440v.
Will contact Inverter Drive Supermarket
Regards
Mike

**mekanik** · 20-04-2023

deleted

**JohnHaine** · 20-04-2023

Found this on Amazon
https://www.amazon.co.uk/Inverter-AT.../dp/B0892L6CZM

**mekanik** · 20-04-2023

Found this on Aliexpress
the video shows the chappy with a meter 220v input and outputting 410V so should be good to go, the feedback is good as well, downside being the month or so shipping plus my last purchase from Ali never arrived.would be nice to put this disaster to bed.
Kindest Regards
Mike
https://www.aliexpress.com/item/1005...d=CBSN0q3HLTrF

**m_c** · 20-04-2023

https://www.aliexpress.com/store/gro...000324416.html

It's worth going through the different listings, as I've see different delivery options amongst seemingly identical VFDs.

Other make to search for is Ecogoo.

**rnr107** · 25-04-2023

Why go 3 phases ? for such a small motor the cheapest and easiest option is to buy a new single phase motor...
fairly cheap on eBay.
Unless this motor is of a special form factor or something ?