VFD on single phase to control speed?

[beeza650Participant @beeza650]

Ok real newbie question here – am I right in thinking I can just plug a normal single phase 240v motor into a VFD and gain some flexibility on the speed it spins?

I read somewhere about the difference between 50hz and 60hz was 25% increase in speed. That’s a useful amount, What about slow down too?

With the price of a used VFD being very low I’m wondering if this would a useful add in to 4 speed Emco mill (on a maximat V10P) as it doesn’t go that slow or fast as-is.

Thanks

[John HaineParticipant @johnhaine32865]

Vfds need a 3 phase motor

[Robert Atkinson 2Participant @robertatkinson2]

As John suggests most VFDs will not work on with a single phase load (It would actually be connected across two of the output phases) The issue is that the VFD will think there is a fault. You could possibly connect a pair of “dummy” loads To the other phase but it might not work. Another issue is that the “neutral” connection of the output will be at least 120V above ground and this could cause functional / safety issues.
I know it is fairly integrated but you would get other benefits if you replaced the motor with a 3 phase one.
You can get single phase output VFDs but they are uncommon. This makes them relatively expensive. Most are not suitable for capacitor or centrifugal start motors. Proper details of the motor would be required before anything else can be decided.

Robert.

[JasonBModerator @jasonb]

Your chances of finding a miil head/column on it’s own are quite slim. If you want to stick with Emco then the head off an FB2 would be better with its six speeds which was also fitted to the last of these lathes as that went down to 120rpm which should be slow enough for most things.

But if you do find an FB2 may as well leave it as a mill rather than the compromises of a combi machine.

[JasonB]

On JasonB Said:

Your chances of finding a miil head/column on it’s own are quite slim. If you want to stick with Emco then the head off an FB2 would be better with its six speeds which was also fitted to the last of these lathes as that went down to 120rpm which should be slow enough for most things.

But if you do find an FB2 may as well leave it as a mill rather than the compromises of a combi machine.

Yup I’m looking for an FB2 but they aren’t common whereas the 4 speed mill heads are available so I will get one as a stop gap.

I don’t really have space for a separate mill so if I do come across a full FB2 I’ll either sell the bed or keep in storage somehow for when I come to sell it, there’s space under the bench.

[Ian PParticipant @ianp]

As far as I know the Wein motors Emco fitted to the 4 speed milling heads were actually 3 phase motors (wired for Steinmetz with a capacitor).

I stripped out the wiring and capacitor that were in my Emco ‘Mentor’ mill, fitted a VFD about 10 years ago. I had to make a few guesses/assumptions as to the VFD settings as the motor ID plate was missing but I run the motor from 4Hz to 120Hz with no problems. I dont do heavy work but the motor has never been more than just warm.

Beeza650, I suggest checking the colours of the wires coming out of the motor, if they are brown, blue, black then its a 3 phase motor.

Ian P

 

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