phase converter

[Fern]

This is my first post to this site. I picked up a 3 phase air compressor for cheap and plan to use a Phase a Matic phase converter to set it up on my single phase service. I had done so previously with an overhead hoist and had no problems. I ordered the converter from Grainger's. The motor on the compressor is 5 HP. I purchased a converter rated for 5 to 8 HP.
Upon reading the directions that came with the converter I learned that the HP of the motor would be reduced by 1/3 and that I should either reduce the pulley size by 1/3 or set up the converter as a rotary converter (some thing I would like to avoid). At this point I could return the converter and buy a single phase compressor for a few hundred dollars more. I just don't want to give up that easily.
The compressor is over sized for my shop and I was wondering if I could set the max pressure down a bit to reduce the load on the motor and get away with using the converter as it is instead of converting it to a rotary converter. Also the motor is connected to a starter box. Any advice or comments appreciated.

 

[C96]

Sorry, but ditch the phase converter idea and get yourself a good quality single phase 5hp replacement motor. You'll be glad you did.

 

[Norcal]

IMO, a static phase converter is worth less then a wad of soiled bathroom tissue, all they do is start the 3Ø motor & drop out, the 3Ø motor is then single phasing, this is not good on loads like a compressor.

As said above get a single phase replacement motor, you'll be better off.

 

[66dave]

Fern-

As others have stated save time & effort and get a quality single phase motor. I messed with a static convertor, it's OK. Then. I moved to a rotory for other tools and it is ALLOt better setup.

Going back to the single phase motor, buy a quality unit. I have bought a few of these, no issues the people are very fair:

http://www.ebay.com/itm/L1410T-5-HP...376?pt=LH_DefaultDomain_0&hash=item2ed0549798

As a disclaimer I am not affiliated with the people on that ebay link.

 

[930dreamer]

Return the item from Grainger's and build a 10hp rotary phase converter.

 

[JoeFin]

Return the item from Grainger's and build a 10hp rotary phase converter.

Practical Machinist forum has a section devoted to the design and build of rotary phase converters complete with drawings. Some of the guys take them out to the Nth degree and include remote stop start stations

http://www.practicalmachinist.com/vb/transformers-phase-converters-vfd/

Personally - I would go the single phase motor route "IF" the compressor was to be my only 3 phase load.

What makes 3 phase power a necessity are 3 phase machine tools with multiple motors where the quality of the power effects the cut and finish of the cut

 

[jeff000]

Just buy a vfd and use it for phase conversion. We do it all the time.

 

[Norcal]

Use of a VFD for phase conversion is inexpensive for 3 HP & less, after that you need a 3Ø drive that the phase loss protection can be disabled & then has to be derated 50% so for a 5 HP motor, you would need a 10 HP drive & so on, it can get real expensive in a hurry.

 

[Fern]

Thanks for the input.

 

[Fern]

Fern-

As others have stated save time & effort and get a quality single phase motor. I messed with a static convertor, it's OK. Then. I moved to a rotory for other tools and it is ALLOt better setup.

Going back to the single phase motor, buy a quality unit. I have bought a few of these, no issues the people are very fair:

http://www.ebay.com/itm/L1410T-5-HP...376?pt=LH_DefaultDomain_0&hash=item2ed0549798

As a disclaimer I am not affiliated with the people on that ebay link.

Thanks for the info. I looked at this on e-bay. Costs less than the phase converter. The motor that is on the compressor now has a starter. According to the tag it can be used for single phase. I do not know if I can use this for the single phase motor or if it even needs one. Also concerned about direction of rotation.

 

[930dreamer]

Thanks for the info. I looked at this on e-bay. Costs less than the phase converter. The motor that is on the compressor now has a starter. According to the tag it can be used for single phase. I do not know if I can use this for the single phase motor or if it even needs one. Also concerned about direction of rotation.

The picture is of a magnetic starter switch, you will need the amp/volt rating specs of the motor you are going to use before that can be answered.

 

[jeff000]

Use of a VFD for phase conversion is inexpensive for 3 HP & less, after that you need a 3Ø drive that the phase loss protection can be disabled & then has to be derated 50% so for a 5 HP motor, you would need a 10 HP drive & so on, it can get real expensive in a hurry.

A 10HP drive shouldn't be too expensive. But I guess it's all relative to the cost of the project.
I'd personally just change out the motor out thinking back on it.

 

[Charliefoxtrot]

Thanks for the info. I looked at this on e-bay. Costs less than the phase converter. The motor that is on the compressor now has a starter. According to the tag it can be used for single phase. I do not know if I can use this for the single phase motor or if it even needs one. Also concerned about direction of rotation.

youll have to get the specs on the motor youre getting, like super dreamer said, namely the FLA of the motor... and then source motor overloads a.k.a. heaters to match up the new motors FLA rating. Look into the starter box for a big chart of heater sizes, and then google the part number, youll find it on ebay too most likely.

 

[marinusdees]

Compressor motors do NOT like phase convertors.

 

[Fern]

The picture is of a magnetic starter switch, you will need the amp/volt rating specs of the motor you are going to use before that can be answered.

The motors I am seeing in e-bay are 230 V 23 Amp

http://www.ebay.com/itm/L1410T-5-HP...376?pt=LH_DefaultDomain_0&hash=item2ed0549798

There are also motors from Grainger that have similar specs but cost more.
https://www.grainger.com/product/DAYTON-GP-Mtr-5K968?functionCode=P2IDP2PCP
and
https://www.grainger.com/product/6K854?cm_sp=HIO-_-HIDP-_-RR_VTV70300505&cm_vc=IDPRRZ13

Any thoughts?