Phase Converter Sizing & Compressor

[TravisR100]

I'm looking at purchasing a Super Mini Mill 2 (10K spindle) and an SL-10. From all the reading I've done it seems like the Phaseperfect phase converters are the way to go. My question is in regards to sizing. These machines are going in a home workshop. The Phaseperfect is supposed to be sized according to the actual horsepower of the machine. I've figured out from reading that the 15 HP rating of each of these machines is the max horsepower based on some short period of time. The nameplate rating on the motor is something less however Haas doesn't tell you what it is.

From reading Haas' preparation document it says that each of these machines has or needs a 40A machine breaker with a recommended service of 50A.

I called Phaseperfect. They seemed to think that I needed the PT-355 if I was only running each machine separately or the PT-380 if I wanted to be able to run them both at the same time. With the PT-355 they said I'd need a 125A breaker on the input side and for the PT-380 a 200A breaker. They were using the 1.73 factor to get the conversion on the single phase side. I think they were also concerned with any starting loads. My question is, do you think those recommendations are about right? Or is that overkill?

My house currently has the standard 200A service. In talking with an electrician no matter what I do I'm going to need to upgrade the service coming into the house to 400A from 200A at a cost of somewhere between $9K-$12K. I'm then looking at another $4700 (PT-355) or $6200 (PT-380) for the phase converter.

To throw another variable into the equation, I'm looking at a rotary screw compressor. The Chicago Pneumatic seems to be the most cost effective solution with a QRS 7.5 with dryer costing $5937 for the single phase model or $5244 for the 3 phase. So, do I go with the 3 phase and the larger phase converter? Can I get away with the smaller phase converter, run both Haas machines, and the compressor?

All of this is a bit confusing to be sure. The only reason I'd want to go with the QRS 7.5 as opposed to the 5 or 3 HP models is that the 7.5 is rated for 21CFM for airflow and I have a small blasting cabinet. That 21CFM rating is at the max pressure of 150 PSI. I think the blasting cabinet only uses about 20CFM at 90PSI. Won't I get a better CFM rating from the compressor at 90 PSI as opposed to max pressure (150PSI)? Note that I'd never plan on running the blasting cabinet at the same time as either of the Haas machines.

Wow, the price of this machine is really starting to add up when I figure in a new compressor, phase converter, and electrical service. And I haven't even gotten to tooling yet.

[Al_The_Man]

You are probably realizing that you are approaching a small industrial set up running from a residential service!
It may soon reach the point where you are going to bite the bullet and go into an industrial 3 phase equipped shop?
Al.

[TravisR100]

Any opinions on the sizing of the phase converter, Al?

[Al_The_Man]

The maximum hp rating is generally stipulated for 1/2 hr run period, continuous is generally two thirds that.
If you are going to run two or three items at a time, you have to consider your residential load also, such as stoves, dryer, air conditioner etc, being on at the same time, so I would say the 400amp would be right.
You may just squeak by with the 20hp rated PT-355, but often it is best to go with the higher margin, if later you find you need more capacity, you may kick yourself for not paying the extra.
Al.

[Matt@RFR]

If I were you, I'd look in to having your power company set you up with 3 phase. The cost of the single phase, 400A drop plus the phase converter may not be that much less than going 3 phase completely.

For your reference, I'm running a VF-2ss on a 200A single phase drop with a 50HP American Rotary phase converter. I can tell you that I'm RIGHT on the edge of not having a big enough service. I bought that phase converter incase I ever add machinery. American Rotary had to build me a custom panel with a **** load of capacitors and some different electronics just so I would keep from blowing the fuses on the power pole!

[TEntpeg]

[QUOTE=TravisR100;643886]I'm looking at purchasing a Super Mini Mill 2 (10K spindle) and an SL-10. From all the reading I've done it seems like the Phaseperfect phase converters are the way to go.

[snip]

Travis, we are in the same boat.
I am a long time lurker and hobby machinest wannabe.
The price of admission is really steep for a hobby but in the end you own the shop and the machines for a life time of use. What could be better?

All of the rotary phase converter (RPC) folks will tell you the same thing regarding the power requirements. You can do the math yourself to prove it. The last thing you want to do is have the Haas tech tell you that the intermittent alarm problem is your marginal power supply. Go for the largest phase converter you can afford. I run a 40hp RPC off a 200 amp subpanel for a VF 1 and an SL 10. There is only me in the shop and I really not sure that I have the projects to keep them both running simultaneously. Besides, if the power consumption runs too high you may have unmarked vehicles surveiling your "grow-op"

The next question is why do you think that you need a digital phase converter? I think that four members on this forum run RPCs for their machines including a VF 2SS.
Why spend $6200 for a digital when you can get a 40hp RPC delivered for less than $3000?

I spent quite a bit less than what you are being quoted to upgrade to 400 amps.
I contracted out the trenching to run a new line. The electrician hooked up the incoming power to the new 400 amp service panel, made the existing house panel into subpanel "A" and ran 4-0 to subpanel "B", which became the shop panel. Then you can run the rest of the shop power yourself. Learn how to bend conduit and all about ampacity in "Ugly's Electrical Refernces" ISBN 0-9623229-6-2. Just make sure that you do it all to code or above.

A rotary screw compressor sure looks nice, but do you want to spend your hard earned cash on tooling, toys and stock or do you want it sitting in a compressor shed? A 5 hp reciprocating 220v compressor with a 5 micron pre-filter, a coalescing filter and a dryer should do about 80% of what you want for less than $2000 or are you really going to be sand blasting all day long without stopping ??? Just askin

regards

TEntpeg

[TravisR100]

Tentpeg, thanks for the info. Reading the Haas literature it seems that they highly recommend a digital phase converter for their machines. I just didn't want them to be able to blame any problems on weak/bad power. My other issue is the heat from a rotary phase converter. I have a small space and even the small rotary I have now puts out an awful lot of heat.

You had to have the elctric company put in the new 400 Amp service though, right?

My issue with the compressor is my neighbors. I will work almost exclusively at night. I don't think they'll appreciate the noise from the piston compressor.

[l u k e]

If I were you, I'd look in to having your power company set you up with 3 phase.

I checked into that myself. They (APS) have 3 phase power 25 feet from my shop (for the place next door) they wanted $10,000.00 (yes 10K) to supply me 3 phase power!

That's BS!

[Matt@RFR]

It is rediculous, I agree there. But if the choice is $10k for 3 phase or $6200for a phase converter, get the three phase!

I will say though, that the Haas tech that set my mill up commented on how good my power is through my phase converter...and it's not digital. I'd just rather do without the heat and noise.

[123tool]

I just had a TM-1P and a SL-10 delivered last week, the SL-10 sat at the riggers for months waiting for the mill. I'm in a home shop and plan to use the PT-355 to power both... hopefully at the same time. If the machines aren't under full load how much power could they draw, the hp is always rated higher.

Travis, it all depends on your business, prototypes or production and how much to you plan to run. If your business is going strong then go big, if your just starting take it one step at a time. Let us know what you decide.

Doug

[Geof]

Before comitting yourself to a compressor look around and see if you can find one that keeps the motor running and cycles the air end on and off when the set pressure is reached.

I am pretty sure the Chicago Pneumatic unit turns the motor off and when it restarts you get a big starting surge which could pull your voltage down low enough to trigger an alarm on the CNC machines. However if you have this motor running constantly it enhances the quality of the power from the phase converter and acts as a bit of reserve power when these machines start.

[123CNC]

Geoff makes a good point about the load/unload of the compressor motor.

Regarding noise and neighbors, rotary screws are much quietier then reciprocating, but you may also want to consider scroll compressors. They are inherently quiet and can be quite efficient if you get a multiple compressor unit that is staged to run based on demand.