New shop... Need 3 phase help

[Txchevy18]

--------------------------------------------------------------------------------

Well if all goes well I'll be moving my small shop in the back of my dads
shop to my new house. It has a fairly new 30 x 60 stick built shop. I can't wait!

I've got a pretty good collection of tools and need some help finding the best way to power the 3 phase equipment.

9 x 42 Supermax Vertical Mill
60 x 20 Okuma Lathe (10hp)
14" cold saw ( 5hp )
24" gearhead Drill press (3hp)
CNC bridgeport in the future ( I hope)

I was thinking of separate vfds for each machine and a large rotary converter for the lathe. If I did this it would be the most expensive option but, possibly the most efficient. It doesn't seem to make sense to run a 25-30hp RPC for a 5hp load. Running more than one piece of equipment is very unlikely since its a one man shop.

Any thoughts yall?

 

[buzz4041]

I like your thinking. Only draw back is if you expand and get another employee but if you don't see that in the future go for it.

 

[eriksalo]

I have essentially this same configuration in lesser numbers (big VMC, and a 3hp 3PH Tablesaw). VMC=Vertical Machining Center = Milling machine with tool changer.

What I did was use a VFD for the tablesaw (got one cheap on eBay, works great) and then built a 30hp rotary converter for the VMC. The configuration has worked fine for me.

If you get a good Rotary converter (that is, one with the impedance matched between the legs), it uses very little power by itself. It only costs a few pennies per day to run even a large idler motor.

The pain in the neck from my perspective is that the rotary phase converter is loud. It's OK if I'm running the milling machine (which is also loud) but if I'm just turning on the tablesaw for the odd cut, that humming 30hp motor drowns out the radio and messes up my mechanic "zen."

 

[larry_g]

I'm not familiar with the lathe but if it has a clutch on it and does not have to start fully loaded then you will not need 2.5-3x the HP rating for the RPC. You also have the capabilities of paralleling RPC's to handle increased loads. Hopefully 930dreamer will chime in here and tell you how he has done it.

lg
no neat sig line

 

[930dreamer]

Although I didn't need the larger hp converters, I wired three in parallel to find the largest motor I could start. My main set up was a 7.5 hp and a 10hp, with another 10 hp for the bigger stuff. With this set up I can start a 30 hp motor.
I used a disconnect for each motor and had a test lead coming out of the third disconnect. If you go the multi idler route ensure you size the wire accordingly. I have a pallet of three phase motors so I'm constantly changing my set up.
The large inrush amps are an issue starting a large idler, I used a pony motor to spin it up to speed.
It's a cleaner set up using a single large idler, ie less stuff to wire, disconnects. You could also look into adding a three phase panel off the RPC and wire into it (my next step).
Look at placing the converter outside if possible and keep us updated on your progress.

 

[RCStocker]

You need phase converters which are not cheap. You will loose about 1/3 of the hp rating on your moters. If you can change the moters out for 220v you will be much better off and money ahead. There are cheap inverters and you can make your own but you will need larger moters than you are using to make one. Look it up. The world is at your finger tips here on the web. You can find out how to make any inverter but hang on to your wallet.
Old 3 phase machinery is cheap for a reason. Very few have 3 phase power and the electric companies in many places will not even run it to your shop. Check with the power company and see if they will run 3 phase. It will not be cheap. We are talking about hundred of dollars for inverters depending on the moter hp.

Nice shop space. Cut the grass down around the building. Make it look sharp. LOL
The grass bugs me. Or get a couple of sheep and fence it in. LOL
Thank your dad and make sure if he needs help you find time to help him.
That shop space would be $2500 per month in California.

 

[eriksalo]

If you are making 3 phase power with a proper rotary phase converter (one with a spinning 3 phase motor), you will not lose any power in your load motors.

There is a type of 3 phase converter called a "static" converter, that has no spinning motor (hence the name static) and it makes power essentially by starting your motor with some big capacitors and then running it on single phase power. In that case you loose something more than 1/3 of the rated power of the load motor.

 

[Txchevy18]

I may have to consider having an employee if work keeps piling up. I mentioned to a few guys at work I was getting my own shop I've already got guys wanting custom work done. I've got a full time job as a heavy equipment tech but, I may considering going fulltime if the demand is there.

I've never heard a RPC in person but, the noise would make sense. I've been considering building a small side room to house the compressor and air dryer so putting it in there would help the noise issue. Last thing I want is a to not be able to think thanks to the whine of the converter.

I've searched quite a bit, I just wanted to get some real world feedback from guys that actually have experience using them.

Bringing 3 phase in isn't even an option. I'm in a residential area on 1.5 acres.
Last time I asked about bring 3 phase to a building it was $1,000/foot and this was to just upgrade from 208v 3 phase to 240/480v and that was when the pole was only across the alley from the building.

I agree 100% about the grass, it bugs me every time I go over with the Realtor. I should sign paperwork next week and then I can actually start taking care of things. The property was a foreclosure and hasn't been maintained in two years. Wow $2500/mo that is almost twice my mortgage.

Here's a link to the lathe. Its from the mid 60's and built like a tank. It is direct drive with 3 v belts off a 10hp 3 phase motor. The motor plate shows it can potentially pull 80amps @ full load. I highly dout I'll ever fully load this lathe but, its better to have it and not need it than need it and not have it.

http://www.lathes.co.uk/okuma/

If I go RPC I plan on a separate 3 phase panel with breakers protecting all of my equipment. There is a old man with a shop a few miles away that has an entire manual machine shop ran off a 15hp RPC and swears by it. I was more curious if it was a better idea to go with Vfds in some instances. A plus to the VFD is that you can control the speed of the spindle through the frequency control which is a cool feature.

Here's a shot from the street and from standing on the roof. I can't wait to get keys on my first house.

My dad coming off the roof last week when were up there with the inspector.