Rotary Phase converters

[veno]

Hi guys... been a while ...

I brought home a Index model 555 vertical mill... It has a rather large frame doerr electric motor rated @ 2hp... the X and Y axis are powered with a 3/4hp GE motor...

the question is.. do I or can I use a 5hp phase converter or do I need a larger one because of the age of the machine.... the year model I was told is 1964..

it always help to have a pic!

 

[Torque1st]

A 5HP phase converter should work well.

 

[A_Pmech]

A 5HP phase converter should work well.

Agreed.

 

[veno]

I was told due to the age of the motor... it would take a hard start compared to a 56 nema frame.. I think this motor is a "J" frame? its twice the size of the normal 2hp motors of today


Next Question.... static? or rotary?.. the reason I ask is you on the table in the pic a 4 to 8hp static converter...

 

[larry_g]

http://www.practicalmachinist.com/vb/index.php

The above site has a whole subforum devoted to this. I have done some research on this and settled on a rotary. The balanced rotary will give you virtually full power 3 phase. The static converter will only run the motor on two of the three phases with asscoiated loss of power. Due to the fact that you have 2 seperate motors on you mill a VFD is not the single solution to your problem. If you have a bit of electrical ability you can build a rotary with $100 in used parts and be on your way. I have a 3 horse rotary and have had no problems with it in the years since I built it.

I hope you enjoy the mill. I have a model 40 and it is a great machine for its size. Do you know that Wells-Index still has support for these machines and will regrind the spindle from BS9 to R8 if you need the conversion.

lg
no neat sig line

 

[A_Pmech]

Definitely rotary. Static converters are not a good choice as the motor will only put out 2/3rds rated power on a static converter. Attempting to run the motor at rated power will burn it up. Plus, a balanced rotary converter provides power almost as good as the power company and you can use it just like "real" 3-phase.

Do you plan to purchase any other machines? If so, you might consider building the 10HP "Fitch Williams" design, the plans for which are in the Phase Converters and VFD's forum under the "Phase Converter Plans" sticky.

 

[Torque1st]

I have a 7.5HP lathe that needs 3-Phase. I expect to pick up more 3-Phase machines so I am making a 5-10-15HP pony start converter. I will start the 5HP idler with the pony motor and then start the 10HP idler from that if needed. Together they will provide a 15HP RPC. You can find all kinds of ideas and info on Practical Machinist.

http://www.practicalmachinist.com/vb/forumdisplay.php?f=11

 

[rsanter]

why not use a VFD?

bob

 

[Torque1st]

why not use a VFD?

bob

Seems he has more than one motor to power.

 

[Norcal]

Hi guys... been a while ...

I brought home a Index model 555 vertical mill... It has a rather large frame doerr electric motor rated @ 2hp... the X and Y axis are powered with a 3/4hp GE motor...

the question is.. do I or can I use a 5hp phase converter or do I need a larger one because of the age of the machine.... the year model I was told is 1964..

it always help to have a pic!

If you have a shotgun, that static converter sitting on the table makes a good substitute for a clay pidgeon. Use a VFD or get a RPC, a static converter will just start your machine but will just be single phasing while running resulting in a loss of HP. (About 1/3).

 

[veno]

Hello and thanks for the replies....

as for building a converter.. I have no Doubt I could provided I had step by step instructions,,,,.. the schematics and its values are Greek to me.... since I dont understand the values and the relationships of the components....


I am sure I could build one.. just dont want to go ****... in the process...and not understanding what I'm doing.. is the blind leading the blind...

now wiring.. straight simple wire is easy...as I wired my whole shop....single phase and 3 phase no problem.... I am good at research.. I dont know what values a capacitor needs nor how to use one properly... and that is dangerous...


So I guess I am stuck buying one of the ready made converters.. like Phase-O-matic.. or one of 100 other companies make...

since I am in that boat.... got a suggestion on where to get a good one and the lowest cost?

unless some one has very explicit schematics complete with names and part numbers...

 

[Jim Stabe]

I'm about as electrically inept as you can get but I built one and it works great. I got contactors from an electrical surplus store (https://www.surpluscenter.com/sort.asp?catname=electric&keyword=ERRA has them also) the same with the capacitors. I have less than $100 in mine. I have a really good article on how they work and how to build one but it is too big a file to attach here. If you pm me with your email address I'll send it to you along with the schematics that I used to build mine




.

 

[larry_g]

I'm about as electrically inept as you can get....

That is some great looking ineptitude you have there.

lg
no neat sig line

 

[Jim Stabe]

That is some great looking ineptitude you have there.

lg
no neat sig line

Thanks. I can connect the dots, I just have trouble defining what the dots should be.

 

[veno]

so a VFD will work as well as a Rotary ?

 

[Torque1st]

A VFD will only run one motor at a time and it has to be programmed to run that motor.

People at Practical Machinist give good reviews to American Rotary converters.

 

[rsanter]

I VFD takes AC in and converts to DC
it then converts back to AC
so it dosent care of you are inputting 3ph or 1 ph
it will deal with it either way.
the thing you need to look at is what the rating is on the VFD
often if it is rated at 5hp for 3ph in, 3ph out
then it will only be rated for 3-4 hp for 1ph in, 3ph out
it will either be in the specs or available from the manufacturer.

for wiring from 220 1 ph
you will connect ground and then to 2 of the 3 legs on the input line
for output you will connect to all 3 legs of the output line
if the motor rotation is opposite of what you are expecting then swap
2 of the wires on the output line

dosent get much easier

what some people will do is to get 1 VFD and wire it to several plugs in the garage so it can power several different machines. then to select the machine you run at the time you only have to use a disconnect switch at that machine which is generally the original switch thats on the machine

another option
you have a static converter
get a spare 3 ph motor and run it off the static converter
you have now made a rotary converter

bob

 

[APEowner]

I made a rotary converter for a friend of mine and it works just like it should but when I needed one for my shop I decided that by the time I figured out what I needed for parts, sourced them built the device and fine tuned it that my labor costs would be well above the cost of buying one. I bought an American Rotary hooked it up and went to work.

 

[veno]

right.. I get the per unit per motor.... so a VFD is comparable to a rotary in respect to phase % equality?

I just know I dont want a static......

I found a GE

http://cgi.ebay.com/3HP-230V-GE-1PH...ltDomain_0&hash=item53de027e71#ht_1161wt_1166

 

[930dreamer]

I built a 10 hp RPC to run my 5 hp 3 phase compressor. I use a pony motor to spin the idler to speed then supply the 240v, works great, no start or runs Caps used yet.

 

[Torque1st]

Are you prepared to wire in the mill controls to the VFD??? If you can't read schematics, understand them, modify them, and pick out components, or build a RPC then I doubt you will be able to wire in a VFD. The VFD requires programming, understanding their control schematics, troubleshooting from schematics, and adapting them to your application.

RPC's are simple.

 

[veno]

another option
you have a static converter
get a spare 3 ph motor and run it off the static converter
you have now made a rotary converter

bob

really? would this be phase balanced ? what about startup?

you'll have to forgive me.. as I am really inept when it comes to motor controlling

 

[rsanter]

really? would this be phase balanced ? what about startup?

you'll have to forgive me.. as I am really inept when it comes to motor controlling

wont be completly ballanced
if you put a power quality meter on it your readings wont be very good but a motor will accomodate unballanced legs.
the way a rotary phase converter works is that it runs on the 2 legs (or phases) comming in and has capacitors bridged to the third phase.
the capacitors as well as the motor operating will 'fill in' that third phase

bob

 

[Torque1st]

Even without capacitors the motor acts like a rotary transformer inducing a third phase into the other winding in the motor. That third phase can be used along with the single original phase to run three phase motors.

Go to the Practical Machinist site and read all about it. There is for more information there than we could give you in a thousand posts here.

 

[kool55]

veno, I was going to build a RPC but had trouble locating a used motor in my area. So I bought a 7.5 hp. RPC from Ken at Elimia. Happy with it. Set it up to run 3 machines. My thread on it is somewhere in here. By the way I started out with a VFD. Good luck.

 

[veno]

Thanks. I can connect the dots, I just have trouble defining what the dots should be.

Jim.. thanks for the email.... I read a bunch.. I LOOKED AT YOUR DRAWINGS.... very easy to follow... thanks...

I guess I got impatient this morning... as I want the mill up and running... so I ordered a rotary converter from Ken at Elimia... not based on the last post here.. but based on the research on all the types of phase converters I found in the past 3 days.....

Elimia.. uses Baldor.. thats a big plus. plus he is a good old redneck Alabama boy...

I got the 7.5 CNC version with the digital readout...

I want to thank everyone for the input..... I will gather the parts to make another converter.... for my own self fulfillment....just because I want to.... I have never set out and failed at anything I wanted to do.. and this is no exception....

Torque1st... didnt say I did not know how to read a schematic.. just said I dont understand the relationship and values...I know what the symbols are... thanks for your encouragement and respectfulness in helping me through this...... hope I can someday return the respect...

Torque1st.. the only reason I am not a electrician??? Color Blind.... the NAVY picked that for my job based on my abilities... but I am color blind..so I did not get it.. in all fairness I have been playing with electricity since I was 6... when I used the transformer from my Aurora HO car track to power my hand made 5 nail electric DC motor/generator...

 

[A_Pmech]

Sounds like you should be up and running in short order!

 

[Torque1st]

I had a cousin (RIP) that went into the service for electronics school but was turned down because he was color blind. He didn't even know he had that problem.

I have been playing with electricals since I was little also. My Aurora HO car track transformer didn't put out enough juice so I built my own. Those cars went real fast at 50VDC... I even wound my own "pancake" motors. A few friends and I made a 30' dragstrip. Some of those cars and motors only made one run before they went up in smoke.

If you know what the symbols are, and you understand the basics like complete circuits, why can't you relate to the "values" etc? Basic electricity and machine control circuits are really simple. No worse than learning how to use your transformer to power a home made motor at a young age. RPC's are basically connect the dots exercises. Electronics and Ohms Law etc etc can get a little trickier than just connecting the dots but you can learn it.

You made the right decision to use a RPC and to just buy one to get started tho. It is not good futzing around with building a RPC when you want to make chips.

Now that you are getting a RPC all you have to do is add idlers to expand the system for when you get more or bigger machines. That PM site has lots of info.

It sounds like you just need a little more experience and some confidence. Anything new has a "Fear Factor", once you have done something you have a "Familiarity Factor". -Go for it!!!