Phase Converter

[Bill Schrade]

My head is spinning. I have a Boyer Shultz 6x12 manual surface grinder. I want to set it up in my home shop and don't know what's best for my situation. 1 HP 3 phase. I ruled out a static converter and there are so many options for RPC and a VFD.
Thanks for your help
Bill

 

[GregSY]

Well...there is a an RPC/VFD forum on this site so try asking there. Lots of guys will jump to recommend a VFD but the RPC has a lot going for it.

 

[wood2steel]

Static converters would be the last alternative; you need to evaluate your environment as to whether you'll be running additional 3 phase equipment or specifically that machine. VFD is great for variable speed options but the RPC is the way to go if you'll be adding other machinery down the road. Think real Hard; 20 years ago I bought a 13" Southbend; set up with a static converter, and I was good for a decade; now I've got almost 50 machines in my Building. Its called Machinist Hoarding.

 

[redlee]

High-Quality Rotary 3 Phase Converters | American Rotary

American Rotary is the manufacturer and distributor of the largest selection of phase converters and transformers online! We are the only phase converter company to offer every type of phase converter - static, rotary and digital.

www.americanrotary.com

Ive had one for years and its been reliable and wouldnt hesitate to buy another from them. If you go that route.

 

[Gordon Heaton]

Another plug for American Rotary. Mine is also around 15 years old, all American made (even the capacitors!) and I work it hard. At least a hundred instant-reversals a day when I'm on the lathe. At the time, it also cost me about 1/3 of what the over-rated Phase-a-matic cost.

 

[Bill Schrade]

Thanks for your replies. RPC it is.

 

[dalmatiangirl61]

Something you should know about rpc's, the base model from any mfr will give you a higher than normal voltage on the third leg, if you have, or plan to get a machine with more sensitive electronics (does not have to be cnc), don't just get the cheapest one they make. I looked at the AR line recently, decided not to go that route for 2 reasons. #1 They do not have the combined HP rating of the Phase A Matic, #2 their controls use a circuit board, and circuit boards just don't seem to last long on our rural power with spikes and dips.

Never done a side by side comparison so cannot say if one is better than the other, and there are still more mfr's to compare to.

 

[Gordon Heaton]

Where I work now they used Phase-a-matic 15hp units and reliability wasn't great. Two failed in less than 5 years and they weren't anywhere near maxed out. I wasn't impressed. The company ponied up for powerco 3-phase a few years ago so no longer an issue. I guess I'm glad my old American Rotary doesn't use circuit boards!

 

[L Vanice]

I have used a second hand Snyder rotary phase converter for around thirty years to run several different machines It works fine, but the company seems to have disappeared.

More recently, I have used 120 V single phase input and up to 1 HP 240 V three phase output VFD's dedicated to one machine each. I got these VFD's pretty cheap on eBay and love the ease of being able to plug them in the wall anywhere instead of needing a 240 V outlet near the machine. The variable speed feature is not a bad thing, but less important than the 120 V input feature to me.

Larry

 

[rons]

I had a Phase-a-matic (what a encouraging name). Returned it and built my own. Started out simple.

All you need (in your case) is a 2-3 Hp motor, 3 pole switch, and a small oil filled capacitor. Search around.

Phase Converters

 

[neilho]

What Rons wrote.

The learning curve is steep at first, but what's needed to start is the knowledge that 220V single phase applied to a 3 phase motor will give you 220V 3 phase at nominal motor speed.

How to get it to speed can be a rope wrapped around the shaft, a teeny single phase motor, or a variety of relays, sensors and starting caps.

Then come the details, but those can be done later. The RPC forum has a lot of good info in it.

 

[Gordon Heaton]

My first one was home-made too. It worked, but it was noisy and not nearly as good as the commercial one. If you're going to roll your own, get a heavy 1800rpm (1725) idler. One capacitor will function but to get the best output usually requires mixing and matching two or three.

 

[dalmatiangirl61]

Where I work now they used Phase-a-matic 15hp units and reliability wasn't great. Two failed in less than 5 years and they weren't anywhere near maxed out. I wasn't impressed. The company ponied up for powerco 3-phase a few years ago so no longer an issue. I guess I'm glad my old American Rotary doesn't use circuit boards!

Which model do you have? I was about to pull the trigger on a Pro Series model, then decided to call and talk to their salesman, he told me that model would have the same HV problem I already had, and recommended the ADX model (add another $1000).

I got the PAM 20hp for free, it was not working, for the cost of a set of caps, some wire, and time, it has been running for 10 years. Never been happy about the voltage, but most of the machines don't care, just the new one.

Way back when I did look at the DIY models, was not impressed with rope starting or a Rube Goldberg pony motor contraption.

AR is heavy on marketing, I would like to see a head to head competition to see what brand is best, or is it all just marketing wank and they all perform equally.

 

[Gordon Heaton]

Just looked, no model number listed. It just says American Rotary 7.5hp-CNC. I think its closer to 20 years old than 15 and its dead simple. I doubt mine would perform any better for you than what you've got. Can you use a line conditioner for the equipment control giving you trouble? I've never seen a 3-phase conditioner but if the control in question doesn't actually use 3-phase it might work.

edit: I guess they are made, but the smallest is 20KVa and looks expensive. https://solahevidutysales.com/solatron_plus_series_3_phase_power_conditioner.htm

From my home-made experience I know you can fine-tune the generated leg by varying the capacitor bank, and the end result depends a bit on the load so you'd have to tune for your sensitive equipment and let the rest go as-is. The design of the PAM makes cap tuning problematic since you won't be able to fit everything under that little cover.

 

[dkmc]

Way back before people knew what a 'phase converter' was....folks would scrounge up a 5 or 10 hp 3 phase motor at the scrap yard and use it as a phase converter. Spin the shaft up close to sycronous speed, connect single phase to 2 of the 3 wires and it runs. Take 3 phase out of the 3 wires and use it to run other 3 phase motors. The first 5hp unit I built cost like $15.
Now days there are instructions and videos online showing in detail how to do this.
You gotta -want to- bad enough.
Be creative.

 

[rons]

A VFD sounds simple doesn't it. No. If there are internal controls it could involve rewiring things.

For a bare bones RPC all you need is a small 2Hp 3 phase motor, a 220V single phase plug, and a piece of rope.
So the real issue is where do you get that small motor. Figure about $50 for a used one.

 

[jim rozen]

For a 3 hp load motor he probably wants to go up to at least a 5 hp idler, 8 might be better.

 

[Froneck]

I think the amount of HP needed on the idler will depend on what kind of motor is being used as the RPC and on the machine. When I started my shop about 7 years ago after selling my large shop that had 480VAC 3 phase power. I went to an auction that had a few 3 phase motors, I won the lot that had a number of 3 phase motors but when I returned to my shop found they were all 1200RPM (6 pole motors), I wasn't concerned since at least one was purchased to be an RPC idler. I selected a 3HP 1200RPM Delta wound motor and built a simple starter for it, no run or balance caps only start since I don't agree with the use of run and balance caps for a multiple machine RPC! I was surprised to see how easily the delta wound motor started and more surprised to see it start the 5HP 1200RPM Wye wound motor on my Hendey 14" lathe as if it were connected to 3 phase! Since that time I started watching motors at HGR Surplus was was able to buy a few 1200RPM motors, I have a few Baldor new in the box 3HP and 5HP 1200RPM motors cheap, well under $100.
Now after 7 years that 3HP Delta wound motor is stil powering the 5HP Hendey and other machines. In the pile I mentioned were two 7.5HP 6 pole motors, one of which I connected to my 24" Hendey lathe. It too will power-up by that 3HP RPC but needs to wind-up yet it will start! Most of the time I start my 14" Hendey and combined with the 3HP RPC they will start the 7.5 6 pole motor (don't remember but it too might be Delta wound) as if connected to 3 phase! On the other hand I have a 7.5HP 4 pole motor on a P&W lathe that will Not start with the 3HP RPC, when I start the 5HP 6 pole motor in the Hendey that 4 pole motor has to wind-up to running speed. The 6 pole delta wound motor runs quite, so quiet I connected it to the light switch so when I turn my lights off the RPC will shut down because I have forgotten to shut it down when leaving the shop it was so quiet!
More to the Point that 3HP Delta wound 6 pole motor will start the motor on my B&S 2L surface Grinder as if connected to 3 phase and has no problem keeping it running when operating under power feed.