VFD For Single To Three Phase

I am not familiar with 3 phase equipment nor VFD and am hoping to get some guidance.

I have a 220V 3 phase boring machine which has automated pneumatic controllers. From my brief inspection today, it looks that all the pneumatic solenoids are 24V and fed by a 20V tap on the internal transformer.

I need to get it running at a location that only has single phase service. I am trying to determine if a VFD would be appropriate to create a reliable 3 phase 220V/60hz supply.

Would I be able to use a VFD to get the machine operating? I have read that VFDs may not be suitable for electronics and are best suited for motors. That makes sense for frequency control, but I would keep it fixed at 60hz.

I hoping a VFD will work appropriately so I can avoid the size & weight of a rotary phase converter.

Motor is 1100kW, 4.7A. Are there any suggested brands/series of VFD’s that I should look at? The machine will see light duty use so I don’t need anything too shelf, but I know to saw away from Amazon crap.

Any insight is welcome. Thank you.

I've had great success with Fuji from Marshall Wolfe; about 10 VFD's so far.
Use the VFD for the motor.
Set up another supply for the control circuits. Typically the control uses one leg of of the 3 phase supply, so you can probably wire directly with single phase 220 volts. The transformer should have voltage labels on the taps being used.
Bob

Overland said:

I've had great success with Fuji from Marshall Wolfe; about 10 VFD's so far.
Use the VFD for the motor.
Set up another supply for the control circuits. Typically the control uses one leg of of the 3 phase supply, so you can probably wire directly with single phase 220 volts. The transformer should have voltage labels on the taps being used.
Bob

Click to expand...

There is a distribution block directly off the power switch. I believe L1 and L2 feed the the transformer. The 0, 220V taps are used on the primary and 0, 20V on the secondary.

Out of curiosity, how does this transformer handle phase? With 2 lines supplying power, they are 120° apart. If I were to power the transformer directly with single phase it would be 180°. Does this make a difference on to the transformer or associated circuits? Just trying to gain clarity on 3 phase stuff. It’s not my forte.

Ok. I’ve really been overthinking this.

Directly wiring the transformer now is making sense, rather than powering it through the existing 3 phase configuration.

Here’s what I’m thinking. Let me know if I’m on the right path.

1. Swap existing twist lock plug to a 240V plug and eliminate L3 wire from master switch on the unit.

2. Distribution block is located after the mains switch and splits to both the motor starter and transformer. Disconnect starter from the distribution block and place VFD between the distro and the starter.

3. Move primary to the 240V tap allowing 240V single phase direct from the distribution block to the transformer power all electronic controls.

This would yield the following for the motor: 240V 1P> main switch> VFD> relay controlled magnetic starter>motor


Am I right?

if you are using the VFD just for the motor you do not want a starter between them
the VFD should be used for start and stop and speed control if desired
VFD's dont like it when you leave them running and disconnect the load
it will work like that anyway but the VFD may not last as long as expected

Wire your 220 volt single phase legs to L1 & L3 of the inverter, then from the inverter directly to the motor.
Wire your switch so that you close the control circuit on the inverter; there is no significant voltage or current on this circuit, and a simple toggle switch is all that's required. You can use a momentary push button switch if you like, as there will be a latch feature on the VFD.
If your primary on the transformer is 220, then connect to your 220 supply. Get yourself a meter to check which secondary terminals are required to give you the correct output voltage.
Use a quality VFD like a Fuji, and the documentation will give you all info you need.
Bob

Overland said:

Wire your 220 volt single phase legs to L1 & L3 of the inverter, then from the inverter directly to the motor.
Wire your switch so that you close the control circuit on the inverter; there is no significant voltage or current on this circuit, and a simple toggle switch is all that's required. You can use a momentary push button switch if you like, as there will be a latch feature on the VFD.
If your primary on the transformer is 220, then connect to your 220 supply. Get yourself a meter to check which secondary terminals are required to give you the correct output voltage.
Use a quality VFD like a Fuji, and the documentation will give you all info you need.
Bob

Click to expand...

Thank you for the reply. I spoke with a tech at Wolf yesterday and ordered a Fuji unit. He was quite helpful.

He had said I my keep the existing starter, (which is relay controlled by the off key switch). I’m not sure if the 3 phase starter will even work missing a phase, so perhaps it is best to bypass and control with a latch/toggle switch only. The manual does show a contractor on the line side.

Transformer only has 20V secondary, but will certainly verify.

One thing I forgot to ask him about is adding a line filter. I think I read that Fuji has some filtering within, but will need to look into this further. It’s very hard to read the manual on an iPhone. I should have the unit in hand shortly.

Don't put any kind of starter or other switching device between the VFD and motor.
Maybe he is suggesting you use the existing key switch and starter to close the control circuit on the VFD.
You may be able to use the existing key switch to control the VFD.
Good luck,
Bob