Phase Converters

[downsizingnow48]

The specs say it is good for 2 hp at 240v and that is what I am doing.

 

[Budweiser John]

Here is a picture of my three phase set up. The converter is a RotoPhase listed for 20Hp max but will operate up to 60HP total load.
This setup has been in service for over 30 years and works flawlessly.

 

[Mendonsy]

YES, many work very nicely on single phase, some won't BUT YOU HAVE TO DERATE THEM. Call AC-TECH (Lenze) or A&B support if you don't believe me.

That is true for any drive designed for 3 phase input, but there are also many drives out there designed specifically to be a phase converter. Here are a few of them. phase-converter-drive

 

[Industrial Toys]

I was talking VFDs specifically.

 

[Erik M]

Love the Art Deco disconnects.

 

[downsizingnow48]

My KB Electronics KBAC 27 is a variable frequency drive (VFD). The complete description from the manufacturer is at the link below.

KBAC-27D Black (952) AC Drives, Nema 4x Inverter - KB-Controls.com, Your online Shopping for AC & DC Controls & Drives

In addition to variable speed, it has a jumper that doubles the max output frequency (60 or 120). I use the 120 setting so my 2hp 3ph 1725rpm motor runs at 0-3450rpm approx. That gives a very workable range of belt speeds suited to grinder belts with different grits from 36 to 400.

It requires single phase input.

They make another model, KBAC 29, that requires three phase input. See link below.

KBAC-29 Black (9528) AC Drives, Nema 4x Inverter - KB-Controls.com, Your online Shopping for AC & DC Controls & Drives

 

[GeneV]

I had this debate a few years ago when I moved my shop out of a facility that had 3p. I looked into vfd's but decided rotary phase for a knee mill and toolroom lathe. I went with American Rotary, got their AD20, 20hp converter. It was around $2100 total with their breakers, floor mount kit, and shipping. Then there was subpanels to install and wiring to fan out to the machines.

 

[grsthegreat]

ive installed many phase converters for people over the years. From $50 craigslist used rotary units to $6,000 electronic models used in center pivot systems. The units i see are usually far larger than ever needed to run a HOME shop environment as they came from machine shops and are being used in a home shop "one tool at a time". My biggest issue with rotary units is there so noisy. VFD are so nice and quiet.

Mind you most machine shops are always noisy, but home shops are not. I always place a disconnect next to the drive unit so its easy to shut down when equipment is not in operation. One customer had me locate shut off switches daisy chained to all his equipment for ease of use.

Most units ive installed in the rotary style are so old i cant even find info or schematics on them any wheres. Some from companies that have been out of business for many years. But the things still work great. Very few parts to go out. VFD are very touchy at times. Have to install surge suppression and lightning strike protection at times. Rotary units can be repaired easily at motor shop if necessary...not so with VFD units. there like computers . Kinda throw away if theres a problem.

 

[texasranger556]

YES, many work very nicely on single phase, some won't BUT YOU HAVE TO DERATE THEM. Call AC-TECH (Lenze) or A&B support if you don't believe me.

I might be staying the obvious here, but it is important to differentiate what is being de-rated.

With a static converter you have to derate the motor being driven. With a VFD you have to derate the 3 phase rating of the VFD itself when feeding it single phase power. So you can get full capacity of the 3 phase motor being driven by oversizing the VFD accordingly. For example I have a 10 HP rated VFD running the 5 HP spindle on my mill, which may still be a little undersized but plenty for my needs.

Several years ago when I was looking for a VFD I didn't see many VFDs with a single phase rating once you get over 2 HP. Maybe that has changed.

 

[chriswheeler]

I started out with the capacitor starting phase converter ( phase O mattic ) at first on my 3 phase 2 hp. drive motor. Didn't like it much, didn't do well under full loads or heavy cutting conditions. I bought a electronic VFD phase converter with a soft start and have been happy every since. Not only do I have a true 3 phase power supply from single phase, but every speed on the step pully has a full range of speeds in that range. In the middle of a cut, you can fine tune the RPM to get rid of chatter for a nicer cut and finish. As a cutter gets a little dull. that can be adjusted for as well. Not cheap by any means, best place to buy, eBay. Mine was from a local dealer for $500, not the cheapest thing out there, but a true 3 phase.
Chris

 

[GeneV]

Several years ago when I was looking for a VFD I didn't see many VFDs with a single phase rating once you get over 2 HP. Maybe that has changed.

Yeh, that was one of my issues not going with a vfd at the time, I got a 5hp lathe.

 

[buickanddeere]

Rotary or static converters are an obsolete design from an era where there wasn稚 much else for choice . Now a 10HP VFD on a 5HP motor is the answer.

 

[buickanddeere]

A three phase VFD supplied with single phase can only produce 57.7% of it’s nameplate capacity .
Constant pressure well pumps are a common use of a VFD to convert single phase into variable frequency three phase .

 

[GeneV]

Rotary or static converters are an obsolete design from an era where there wasn稚 much else for choice . Now a 10HP VFD on a 5HP motor is the answer.

Cool. Technology marches on.

 

[Tractor Seabee]

Out of curiosity; what does a VFD that will drive a 10 HP 3 phase motor and be fed with a single phase circuit cost? I did not even know such an animal exists. VFDs to drive 3 phase motors with a 3 phase input were still becoming popular when I left the mechanical trades. Single phase to single phase was also available for small motors but not economical by any means. In my day when a 3 phase motor had to used on a single phase supply e used an open delta transformer connection. Same problem of loss as you all are discussing in this thread, just oversize the transformers and the primary circuit to match the load with the loss. Inspectors required that we well identify and have a warning label about the "wild leg" which was more than double the phase to ground voltage. You talk open delta to electricians today and they give you a blank look.

Most people do not know that a 3 phase motor will continue to run if one of the 3 legs drops out while running albeit kinda overheats. Do not try to start though. I once worked around a gippo sawmill outfit that used over size 3 phase motors for their loads (cheap on the used market) and they had a small single phase motor rigged to bring the big motor up to operating speed, unloaded, and then the switched on the 3 phase motor, then clutched in the load Burn up a motor, just go get another used one. Amazing what we ran into back in the 50s an 60s. Smaller cities did not have 3 phase power except in industrial areas.

After WWll, all of a sudden folks wanted air-conditioning. Any single phase motor over 5 HP was rare and expensive compared to 3 phase. Power companies did the open delta thing for years till distribution lines caught up. Then even 2HP and up became cheaper and more available in 3 phase. Hermetic motors then brought us a whole new set of problems. Back in those days a Refrigeration Tech had to be good electrician too.

Some day, when I feel like it, I will relate how we powered hermetic compressors for refrigerated trucks using 2 phase alternators driven off the engine and primitive speed/frequency control.

Ron

 

[rangerfredbob]

While on the topic, once I get my shop built I have a 3hp 3 phase 440V mill that I got cheap, my house doesn't have 3 phase... I will be getting a panel set up for the shop but I don't think 3 phase is doable, it is only a 100' run from the power pole though...

Anyone know of any options to get a VFD from single phase 220 to 440V 3 phase?

 

[hiddentacocatneddih]

VFD's are cheap and give you a lot of features. The only option IMHO. But I work on them for a living so my opinion is skewed. I would go with an ABB personally. Allenbradly makes some single phase specific VFD's designed for just single phase input.

Something like a drill press it is really nice because you can get away from pully swapping for speed changes and just change the speed on the drive.

 

[texasranger556]

I bought VFDs used on Craigslist. Paid around $300 for a pair of them with breakers. Be careful buying old ones though, the capacitors can go bad if they sit unused for a long time. I ran them unloaded for a few days after wiring them up.

 

[GeneV]

Out of curiosity; what does a VFD that will drive a 10 HP 3 phase motor and be fed with a single phase circuit cost? I did not even know such an animal exists.

Evidently they do and they're ridiculously cheap.

 

[Mendonsy]

Out of curiosity; what does a VFD that will drive a 10 HP 3 phase motor and be fed with a single phase circuit cost? I did not even know such an animal exists.

The tend to cost about $125 to $150 per hp. Here's a website with several different sizes available from 1 hp to 30 hp. phase converter drives