Rotary Phase Converters

[12vriviera]

we play with different stuff out here..

Graham its 1.732.. thus the near doubling of power rating of the machine.

Use 60 hp drives for 50 hp water wells and it converts on 480 just fine..
same with pumping units. drive is rated at 30 hp for 25 hp motors.
Sinner and Brandon. Cost I was thinking was for bigger stuff like we use plus cabinets.

Lee, its all in the programming. just needs a or b phase shorted to the 3rd input on drive to see a leg there, and programming of the vfd will do what it needs to to create 3 phase..
Only reason we use them out here is for the conversion process, but we use a bit bigger..

still cheaper for motor style phase converter

[ComnRailPwr]

Originally Posted by shortbusdriver

Actually he is partially right. I called 2 different drive suppliers and it seems they have smaller units built for converting 1 to 3 phase. These seem to be limited to around 3hp/11amps however.

To go bigger they said I would have to get a 3 phase input unit, but have to take my machines hp and double it to provide the power I need.

Correct, thats what i have been told

[nwpadmax]

I might be stating the obvious but I used the method with a plain old 3 phase pony motor.

Bring in your 220V single phase (2 hot wires, usually put them through a 2 or 3 pole switch or contactor) to the pony motor and connect to two leads of the 3 motor leads. Then tie your load motor 3 leads into the pony motor 3 leads (this time through a 3 pole switch or contactor). So you have two connections with 3 wires tied together and one with 2 wires tied together at the pony motor box. That's it.

I would hit switch #1 and the pony motor would spin up. Once running, hit switch #2 and the load motor would fire right up. Never had an issue. I have a foggy memory but I think someone told me that the 2 motors should be the same HP and RPM. But I'm not an EE so I won't say that's 100% correct, but that system worked for me on several machines.

Good luck! And ground the chit out of everything, just sayin'.

[12vriviera]

pony motor needs to be bigger than load..
rpm does help to match but I have done it with an 1110 rpm motor on a 1750 rpm equipment.. nothing caught on fire..

[nwpadmax]

No argument that bigger isn't better (lol) but I ran a 2hp pony and 2 hp compressor for years and years with no trouble. The rule I heard was 1:1 (or higher) so I went with it....and nothing caught on fire either

Also make sure the wire size is healthy since I wouldn't be surprised if the currents flowing in that system are probably quite a bit different that what the nameplates indicate....power factors and all....

[12vriviera]

yeah they kinda go wonkey. and harmonics get weird too.

[9724VF350]

Get a Goat, a treadmill, and a lineshaft.

[bobxr50]

I have not found a single phase VFD to 3 phase higher than 5hp.
Anything bigger has to have the VFD 2 times the HP to convert to three phase from single phase.
I have installed capacitors start/run also on 5hp three motors with 240v single phase supply power. The motor gets derated down to around 3.6hp though.

[SINNER]

I have used VFD's to well over 200hp ratings. I think the upper end is 500hp. There is no special VFD for phase conversion. The only parameter is that you use a drive that has no phase loss monitor or it can be switched off when setting up the drive. I always hear that you can do it cheaper with a rotary set up but after a rotary smoked a set of DRO's the drive seemed like a bargain. The infinite speed control and adjustable ramp up-ramp down settings are hard to live without after you ge used to them.

[Scooter's Roofing]

so...

what's the goal here? just curious... the only VFD's I've been around were on drilling rigs

feel free to PM if it's a sensitive subject

[airgrabber70]

Originally Posted by SINNER

I have used VFD's to well over 200hp ratings. I think the upper end is 500hp. There is no special VFD for phase conversion. The only parameter is that you use a drive that has no phase loss monitor or it can be switched off when setting up the drive. I always hear that you can do it cheaper with a rotary set up but after a rotary smoked a set of DRO's the drive seemed like a bargain. The infinite speed control and adjustable ramp up-ramp down settings are hard to live without after you ge used to them.

I agree.
I wish I would have ran VFD's instead of my 20hp rotary system. My machines don't have all the torque they should have and when not running, the phase conv. motor just sits there idling wasting electricity. VFD is pretty hard to beat all around.

[FireMed]

I have a word or pdf file diagram I can send someone. Photobucket wont upload any of these formats. And I need a url for here. If someone can post it for me ill send it to them.

Thanks Jeremie