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Phase converter #181582 10/16/08 08:23 PM
Joined: Apr 2003
Posts: 362
Obsaleet Offline OP
Hi Guys, I need some help with calculating size of phase converter, Line, load overcurrent. The Ice cream maker I am working this up for is 208/240v 30a I don't have access to the motor. It would require dismantling the unit. Any help would be apprciated.


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Re: Phase converter [Re: Obsaleet] #181591 10/17/08 10:52 AM
Joined: Jun 2007
Posts: 301
JValdes Offline
Are you trying to get 3 phase,or are you trying to change Hz?

Re: Phase converter [Re: JValdes] #181597 10/17/08 09:25 PM
Joined: Apr 2003
Posts: 362
Obsaleet Offline OP
Trying to get 3 phase.

Choose your customers, don't let them choose you.
Re: Phase converter [Re: Obsaleet] #181598 10/17/08 09:52 PM
Joined: Jan 2005
Posts: 5,316
renosteinke Offline
Cat Servant
The easiest, best way is with a decent VFD .... it will convert single phase to true three phase.

Re: Phase converter [Re: renosteinke] #181601 10/18/08 10:55 AM
Joined: Jun 2007
Posts: 301
JValdes Offline
The VFD will work fine on the motor, but the controls could be damaged.
If all you need the 3 phase for is the motor, give me the motor name plate information. Specifically HP, voltage and current. Or you can go to Here look for the inexpensive chassis type control. The dimensions will be approximately 4"x4"x2" for controls under 5 HP.

Note: The output of a VFD is not a true sign wave. It is a simulated sign wave derived from the DC bus on board the drive. This output is not as clean as a true sign wave like you would see with a transformer output. That is why you must use caution using motors that are not designed to be used on VFD's. Motors that are VFD rated have magnet wire that is rated for over 1500 volts and in some cases special bearings. Do not let this over concern you. It is just a warning of possible motor failure.

Last edited by JValdes; 10/18/08 11:04 AM.
Re: Phase converter [Re: JValdes] #181610 10/19/08 09:08 PM
Joined: Apr 2003
Posts: 362
Obsaleet Offline OP
Unfortunatly, I would have to dismantle the macine to get at the motor so a VFD would be out.

Choose your customers, don't let them choose you.
Re: Phase converter [Re: Obsaleet] #181618 10/20/08 08:08 AM
Joined: May 2005
Posts: 984
ghost307 Offline
It sounds like you'll need a special motor-generator set; sometimes called a 'rotary phase converter'.
It's a motor turning a generator. In your case, it sounds like you would get one that has a single phase motor driving a three phase generator.

Re: Phase converter [Re: ghost307] #181627 10/20/08 06:35 PM
Joined: Apr 2002
Posts: 7,234
HotLine1 Offline
Phil" is a mfg of rotary and static phase converters.

Situation may be (is) they require ALL info on your load, so you may have to take it apart. How can you hook it up if you don't have the nameplate info? Voltage, HP, etc.

Re: Phase converter [Re: HotLine1] #181741 10/28/08 05:49 AM
Joined: Mar 2005
Posts: 1,213
SteveFehr Offline
Look for the THD rating; a solid state phase converter with an output filter will have low THD, and won't be an issue. They make them specifically for this purpose, it's no different than the inverter on a UPS.

A motor generator may be the cheaper solution, or may not be, solid-state is getting pretty cheap anymore.

Re: Phase converter [Re: SteveFehr] #181912 11/08/08 07:38 AM
Joined: Apr 2003
Posts: 362
Obsaleet Offline OP
Just an update,
I let this slide as there were at least 4 other contractors looking at it. Interesting to note I was the only one who questioned the service 100a 1Phase residential. along with this 30a unit was: centreal A/C, oven, full size copier, 1 deep freezer(she wanted to ad 7 more), and the 20 space panel was full. Someone has already and completed the job. She told me it onlt took him 1.5 hrs. She also told me she signed a contract to fill a large order based on this machine before it was even wired/installed.

This being said I would like to know more about VF drives being used as phase converter. Does it effect the control? What is a THD rating? Why would you want to ever use a rotarty phase convertor if you coul use a drive?


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