Phase converter update

[Dopp Creek]

I did not find a fuse inside the box and there's plenty of char. The replacement my buddy bought is a Cedarburg unit rated for 3-5 hp. What I do
not understand is the original Phase O Matic unit says on the label it is intended to RUN a 3 phase motor on single phase and the new unit says it
is intended to START a 3 phase motor on single phase. Is starting the issue and once the motor is running it will run on the two legs of 220V
single phase? Will this Cedarburg unit work? I'm a 3 phase dummy.

 

[Steve@Advance]

Yes, it will run the 3 phase motor.

Somewhat a play on words. A 3 phase motor needs all three lines to start and run. Without the 3rd line (which would make it a single phase circuit), the motor will only hum, not knowing which way to run. Once up and running, you can remove one line and it will still run, but loose power and raise the amp load on the remaining lines.

The converter tricks the motor into thinking the 3rd line is there. It will start and run but there will be a loss of efficiency without the real 3rd line being there.

Did you get the installation manual?
Installation Manual

 

[timcasbolt]

(quoted from post at 01:49:13 04/10/22) I did not find a fuse inside the box and there's plenty of char. The replacement my buddy bought is a Cedarburg unit rated for 3-5 hp. What I do
not understand is the original Phase O Matic unit says on the label it is intended to RUN a 3 phase motor on single phase and the new unit says it
is intended to START a 3 phase motor on single phase. Is starting the issue and once the motor is running it will run on the two legs of 220V
single phase? Will this Cedarburg unit work? I'm a 3 phase dummy.
<img src=https://www.yesterdaystractors.com/cvphotos/cvphoto122647.jpg>

ou can't go wrong with a Cedarburg. They are the Cadillac of that industry.

 

[Butch(OH)]

Yes its the same unit just different wording. if you need more power from the machine and easier starting at high speed settings find a cheap 3600RPM 3 phase motor and wire it in as an idler. I had the same issue with my Bridgeport. The static converter would not start it when the variable speed was set to high. An idler motor fixed it.

 

[JMOR]

(quoted from post at 22:49:13 04/09/22) I did not find a fuse inside the box and there's plenty of char. The replacement my buddy bought is a Cedarburg unit rated for 3-5 hp. What I do
not understand is the original Phase O Matic unit says on the label it is intended to RUN a 3 phase motor on single phase and the new unit says it
is intended to START a 3 phase motor on single phase. Is starting the issue and once the motor is running it will run on the two legs of 220V
single phase? Will this Cedarburg unit work? I'm a 3 phase dummy.
<img src=https://www.yesterdaystractors.com/cvphotos/cvphoto122647.jpg>

ead my response to your earlier post. Short answer is yes. You can do the same thing these devices do by momentarily connecting a cap from one hot leg to the third motor terminal and remove once started.
All they do is connect the cap and look for a voltage related to Counter EMF that indicates that motor is spinning and then disconnect the cap. Difference from one device to the other is size of cap. Cap size is related to HP of motor.

This post was edited by JMOR on 04/10/2022 at 04:04 pm.

 

[buickanddeere]

Why do you people insist on such primitive and inefficient tech that limits the motor to 57.7% of nameplate power .

 

[MarkB_MI]

A three-phase motor has no starting circuit, because its three phase power provides the rotating field an inductive or synchronous motor needs to start. So the main purpose of a phase converter is to create a rotating field to start the motor.

 

[Butch(OH)]

Everyone's situation is different. While I
can't answer for others I can answer for
me.
I currently run 6 3 phase machine tools
on one rotary converter. 1/2HP, 1HP, 2
3HP, 2-5HP. The Roto phase cost me $600
when I bought it, do the math. Zero issues
for 15 years. A few years ago I had two
shops and 2 3 phase machines at shop #2. I
bought two VFDs on flea bay, neither
would run the machine tools. The
instructions were worthless. They were
upsized 3X as people say they should be. I
called in a professional who works on them
at a local manufacturer and he couldnt
make them work either. I threw them in the
corner and hooked up a $100 static
converter and a $10 idler motor. No more
cheapee VFDs for me, the good ones are
well over 10X the prices shown.

 

[Geo-TH,In]

Mark
My dad passed in 1985. He made both types of converts before electronic converts ( I think they are called VFDs.)
One type used a second 3 phase motor and capacitors.
The second typed used 2 banks of capacitors. One bank acted as the start capacitors. The second bank was the run capacitors.

I don't remember my dad's rule of thumb. X number for MFD's per HP for run caps. 4X the number for start caps.

The one that used a second motor would start with start capacitors and then the motor generated the 3 phase motor. Sometimes dad would remove some metal from the first motor's rotor. I don't remember if dad used run caps on the rotating motor.

It was a matter of adding or removing capacitors to match the motor load. One time we had to use a smaller pulley on the motor to reduce load..

About 3 years ago a farmer converted his irrigation pumps to electric. They used a second motor to make 3 phase.
I asked why they don't use VFDs? The electrician said I don't know, I just wire them...

 

[JMOR]

(quoted from post at 22:07:45 04/10/22)
Why do you people insist on such primitive and inefficient tech that limits the motor to 57.7% of nameplate power .

his 3 phase "converter" (actually gas to 3 phase) cost $20X those VFDs, but runs everything!

 

[buickanddeere]

(quoted from post at 08:23:06 04/11/22) Mark
My dad passed in 1985. He made both types of converts before electronic converts ( I think they are called VFDs.)
One type used a second 3 phase motor and capacitors.
The second typed used 2 banks of capacitors. One bank acted as the start capacitors. The second bank was the run capacitors.

I don't remember my dad's rule of thumb. X number for MFD's per HP for run caps. 4X the number for start caps.

The one that used a second motor would start with start capacitors and then the motor generated the 3 phase motor. Sometimes dad would remove some metal from the first motor's rotor. I don't remember if dad used run caps on the rotating motor.

It was a matter of adding or removing capacitors to match the motor load. One time we had to use a smaller pulley on the motor to reduce load..

About 3 years ago a farmer converted his irrigation pumps to electric. They used a second motor to make 3 phase.
I asked why they don't use VFDs? The electrician said I don't know, I just wire them...

It appears that irrigation farmer does not mind paying for more electricity than he needs to.

 

[Dusty MI]

If I remember right I've seen where a 3 ph motor was used as a converter. The 3 ph motor was started 3 different ways.

First, had a pulley on it that was given a spin by hand/foot then 230v was turned on.

Second, a rope was wrapped around the pulley and pulled to start it spinning then 230v was turned on.

Third, a recoil starter from a small gas engine was installed to spin the 3ph motor before turning on the 230v power.

 

[Dusty MI]

If I remember right I've seen where a 3 ph motor was used as a converter. The 3 ph motor was started 3 different ways.

First, had a pulley on it that was given a spin by hand/foot then 230v was turned on.

Second, a rope was wrapped around the pulley and pulled to start it spinning then 230v was turned on.

Third, a recoil starter from a small gas engine was installed to spin the 3ph motor before turning on the 230v power.

 

[KenH(MI)]

One thing for certain is that all phase converters are not created equally, I've never owned a static converter, but I have owned three rotaries, the first one was built by an electrician in an aluminum box,
he said it was rated at 5 horsepower and I put that thing to the test, and it never let me down, it would start and run a 24 G&E shaper with a 10 HP motor like it was nothing. I built a shop with 200 amp 230
volt three phase and got rid of the converter, my current building has 1200 amp 480, no problems there, bought a second building and a 30 HP rotary because I've got several machines in there that get
occasional use with 15 to 25 HP motors on them, only the 25 gives it fits, and it's the only motor I've ever noticed a power loss with, the others act just like they did when wired to 480. I've also got a 7.5
HP rotary in my hobby shop at the farm which I bought used with no information, and it's actually pretty pathetic, even a 3 HP motor spools up, no instant start. I ordered a few of the chinese VFDs, all pretty
much the same, but not identical, lucked out with one and it came with excellent directions which let me configure the others to where they all work great. The moral of the story is to shop around and ask
questions from the seller, my big converter does what was promised by the manufacturer, but no more, and with the price of a VFD for a 25 HP motor, that ship will never sail.