Rotary Phase Converter Questions/Options

I recently picked up a Monarch 12CK lathe that I need to power. This is the first of several 3 phase machines I will most likely end up with over the next several years. I will not be able to actually dig into the lathe for a year or so as I am in the process of listing our house and moving, but am preparing for my shop at the next place. I have been looking at Rotary Phase Converters and reading a ton of information here on PM. I have two options in front of me right now and am trying to decide if either of these is a good option or if I should keep looking.

The first is a 12 year old, supposedly lightly used Ronk ROTO-CON 2D-1. According to the plates on it, it is there 28KVA model for a 25HP 3 phase motor which makes me believe it is probably a 50hp idler? It requires a 120 amp 1 phase input. I realize that this is completely overkill for my uses and that cost for idle time will be higher, but the price is less than a new basic 10hp RPC and it provides the ability to power any machine I would ever end up with. Other than idle cost and I assume more noise, are there any other issues with running a RPC this big with such a relatively small load? Also, it appears to simply have the starter and run capacitors in the control box but none of the relays and other additional components of the newer ones. Is this an issue?

Another option I have is a buddy of mine has 4 new old stock 25HP 3 phase motors sitting in crates and I can basically have one. I am looking at possibly purchasing a pre-made panel from either American Rotary or North America Phase Converters and going that route. The problem is the RPM listed on the motor plate of these motors appears to be much lower than what both companies require. I have a picture of the plate below. Any thoughts on using one of these motors with a pre-made panel? I have emailed both companies with a picture of the plate as well, but have not heard back from either one yet.

Thank you for your help!

Ronk Panel:



Inside the Ronk Panel:



Ronk Motor:

Your pic for the data tag for the Leroy motor is too small to read, what is rpm?

The Ronk looks pretty clean, i have a Phase a matic, its just caps and an idler, works fine for my machines. If price is right on the Ronk, buy it, just mho.

Nemesis said:

I recently picked up a Monarch 12CK lathe that I need to power. This is the first of several 3 phase machines I will most likely end up with over the next several years. I will not be able to actually dig into the lathe for a year or so as I am in the process of listing our house and moving, but am preparing for my shop at the next place. I have been looking at Rotary Phase Converters and reading a ton of information here on PM. I have two options in front of me right now and am trying to decide if either of these is a good option or if I should keep looking.

The first is a 12 year old, supposedly lightly used Ronk ROTO-CON 2D-1. According to the plates on it, it is there 28KVA model for a 25HP 3 phase motor which makes me believe it is probably a 50hp idler? It requires a 120 amp 1 phase input. I realize that this is completely overkill for my uses and that cost for idle time will be higher, but the price is less than a new basic 10hp RPC and it provides the ability to power any machine I would ever end up with. Other than idle cost and I assume more noise, are there any other issues with running a RPC this big with such a relatively small load? Also, it appears to simply have the starter and run capacitors in the control box but none of the relays and other additional components of the newer ones. Is this an issue?

Another option I have is a buddy of mine has 4 new old stock 25HP 3 phase motors sitting in crates and I can basically have one. I am looking at possibly purchasing a pre-made panel from either American Rotary or North America Phase Converters and going that route. The problem is the RPM listed on the motor plate of these motors appears to be much lower than what both companies require. I have a picture of the plate below. Any thoughts on using one of these motors with a pre-made panel? I have emailed both companies with a picture of the plate as well, but have not heard back from either one yet.

Thank you for your help!

View attachment 263065

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6-Pole motors, those. The lower RPM of the slower motor makes for less annoying noise, 8-pole even less noise. Downside is that the greater pole-count makes for greater losses when the RPC is not working hard and closely matched to the load. As these will NOT be, with the loads you've outlined.

I'm better-served with 4-pole and more granularity as to pilot motor/idler size:

- a 10 HP + a 7.5 HP, + 5 HP for pre-selectable idlers. ONE 10 HP (largest idler) rated starter/control (Phase-Craft and 1750 RPM optimized)

With that and some switch and contactor fu, a one-person shop can run any single one, any two, or all three as a team outputting through the same 27 KVA Delta to Wye transformer and panel.

That because I have load-sets from a mere 1 1/2 HP, 2+ and 3+ HP to over 8 HP, not all of them "easy" starting. Each idler has its own run caps, "fit for the purpose", so there is no need of mucking about with that part once built.

"In other news"...

Ronk was a patent holder - contributor to one of the means RPC designers have chased for better stability over varying loads for the past 115 years and counting. I have NO idea if commercial goods bearing his name in the present-day still incorporate any of that cleverness.

You can bypass a dozen-plus years of ever-repeating rehash here and go directly to a fair-decent roundup and comparison of static and RPC technology done back in 1974.

Given the technology was already 70 years in use at that date and not much has been added, since, it remains a good reference, and is still online:

"Optimization of Phase Converter parameters and effects of voltage variation on their performance"

Roshan Lal Chhabra, Iowa State University, 1974

More than half of it covers the test and instrumentation methodology, which was exceeding through, but only of academic interest.

The "meat" is up-front, and all in ONE place. It covers clever use of transformers+capacitors (See Haas-Kamp, here w/r 3-Phase welders), the Steelman motor-re-configuration (see Steelman-Hass, here for 10EE also), use of saturable reactors, Variacs, and magnetic amplification (see 9100 Bill, several efforts, some reported here also )

"Those who do not learn from history.. enjoy repeating it in internet forums, forever."



2CW ... and three idlers..

dalmatiangirl61 - Sorry about the small picture, I am not sure what happened to that one on the upload. Here are the numbers from the tag as best as I can read them:

Leroy-Somer
B31PK66Q
TEFC
FR - 324T
MO - LS200(M or W)T6
SER - 80346/06
RPM - 1165
HP - 25
PH - 3
AMP - 40
V - 230 A - 64 PF - .(8 or 0)2
V - 460 A - 32 EFF - 88.5 60
SF - 1.15


thermite - Thank you, I'll look into that.

The one thing I could not find in the discussion above, is the hp rating for the monarch lathe you want to run.
It would help to have that available.

jim rozen said:

The one thing I could not find in the discussion above, is the hp rating for the monarch lathe you want to run.
It would help to have that available.

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He said 12CK. 3 HP or 5 HP.

All he needs for that is a 5 HP or 7.5 HP idler. At most a 10 HP - which can prolly also cover any other critter in the average shop that would use a lathe that small, even figuring two or three total machines active at once.

25 HP Idler might save him buying a heating system for the shop, wintertime, but I'd hope it was outdoors arredy, summertimes.

jim, thermite is correct it should either be a 3 or a 5 hp motor on it from everything that I have read on it. I actually haven't been able to check yet as it is being stored at a buddies shop until I move.

Nemesis said:

I recently picked up a Monarch 12CK lathe that I need to power. This is the first of several 3 phase machines I will most likely end up with over the next several years. I will not be able to actually dig into the lathe for a year or so as I am in the process of listing our house and moving, but am preparing for my shop at the next place. I have been looking at Rotary Phase Converters and reading a ton of information here on PM. I have two options in front of me right now and am trying to decide if either of these is a good option or if I should keep looking.

Click to expand...

Then you have a year to do research and build the RPC yourself. And your idler motor dream is way too much. 10 Hp is where you are at, maybe a little less.

Nemesis said:

jim, thermite is correct it should either be a 3 or a 5 hp motor on it from everything that I have read on it. I actually haven't been able to check yet as it is being stored at a buddies shop until I move.

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Read-up on the "supplementry idler" implementation. Main and ONE is good, main and TWO is even better. More than three, total, you probably planned it very wrong!



"Most days" - or at least a few MINUTES ahead of time - a one-man shop knows what machine is to be set-up and run. Putting the variable power rig back of the common distribution runs, all is needed is to bring online the RPC level suited to that load "set" or equivalent of a "cell", were it a factory.

Do the work. Shut 'er down. Select the appropriate level for the next "cell" to be put to use. If any. Part of the shop is still split-phase or Dee Cee OFF split-phase, hand tools, or hand power-tools, some of them AIR, too. RPC need not run the whole damned day, every day.

No point in pissing away money on the power bill, next 20 years, if it is easily cut significantly, year-zero, onward. Might want a set of tires. Or shoes. Or food.

Idlers have run me about $200 - $300 each, shipping included, or with "free" shipping already in their price. That is without yet buying any that are not brand NEW, else smudged shelf spares NOS/NNB or such gone surplus to needs or from shuttered businesses.

No junk, not Chinese, decent brands, Brazil, UK, or USA. Low risk, and with at least 30-day return if not full warrany, IOW.

Downside is that they have trended toward "high efficiency" designs where the older standard ones actually would have made better idlers.

BFD.

The old ones are also generally due for new bearings and not uncommonly laden with a gut full of production-environment dirt and debris, too. New and CLEAN is nicer to work with, and significant TIME is saved.

Sooo, I had emailed the picture of the motor plate to American Rotary to get their take on whether their DIY panels would work with the 25hp motor that I listed above. I just received a call from Sara at American Rotary. She stated that their DIY panels are their AD designed panels with additional capacitors and electronics that allow them to work with almost any motor. She stated that the panel would work with the motor listed without problem even though it is a 6 pole and slower RPM because of these added items. Does this sound right? I also asked if there would be any ramifications from only running say a 3hp motor on such a large panel and idler. She stated this was not an issue either.

I do realize that with the information provided above (that I sincerely appreciate) I could build my own panel, however with time at a premium for me (work is extremely busy with a lot of travel and I have two very young kids), my goal is the most cost effective way to get 3 phase up and running and ideally future proof expansion of adding additional machines. From what I am getting from the responses, the Ronk (which I was able to confirm with Ronk has a 40hp Idler) is a stupid level of overkill for me. The 25hp is also really large, but the motor is free, new, and local and if all I have to do is wire in a ready made panel that will cover any machine I could want to get in the future, it feels like that may be the right direction unless you tell me I am missing something.

Thank you for your help. I look forward to your feedback!

Nemesis said:

Sooo, I had emailed the picture of the motor plate to American Rotary to get their take on whether their DIY panels would work with the 25hp motor that I listed above. I just received a call from Sara at American Rotary. She stated that their DIY panels are their AD designed panels with additional capacitors and electronics that allow them to work with almost any motor. She stated that the panel would work with the motor listed without problem even though it is a 6 pole and slower RPM because of these added items. Does this sound right? I also asked if there would be any ramifications from only running say a 3hp motor on such a large panel and idler. She stated this was not an issue either.

I do realize that with the information provided above (that I sincerely appreciate) I could build my own panel, however with time at a premium for me (work is extremely busy with a lot of travel and I have two very young kids), my goal is the most cost effective way to get 3 phase up and running and ideally future proof expansion of adding additional machines. From what I am getting from the responses, the Ronk (which I was able to confirm with Ronk has a 40hp Idler) is a stupid level of overkill for me. The 25hp is also really large, but the motor is free, new, and local and if all I have to do is wire in a ready made panel that will cover any machine I could want to get in the future, it feels like that may be the right direction unless you tell me I am missing something.

Thank you for your help. I look forward to your feedback!

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Yes, you are "missing something". A pilot motor or "idler" has NO KLEW it will only be asked to be a rotary transformer once up to RPM, "on the step".

At the instant power is applied, it still thinks it is a BIG motor, and draws a starting load according. Many of us start using rope-start or "pony start" at even 10 HP and above - sometimes even less than 10 HP.

My residential electric service was "upgraded" a while back. The new meter and bill include "demand" charges.

My goal - for RECURRING money reasons, coming up 30 years, same house - is to "sneak up" on my loads, then waste less in windage and heating losses whilst running.

'lectric bill arrives every month. "Free" it was never.

thermite, thank you for continuing to walk me through this. Valid point that the electricity to run the RPC is not free and that the idler motor is essentially burning electricity into heat anytime that it is running. I wasn't worrying too much about the electricity consumption to this point as I was following the information from both American Rotarty's and North America's websites. Per American Rotary's site "A rotary phase converter, by itself, is in an idle state and draws only the amount needed to keep it energized. This is only a few kilowatts and in some cases is less than a kilowatt. Your true electrical consumption is based on what the load draws. The rotary phase converter is merely a device electricity passes through on its way to your load.". Per North America's website a 10hp motor in an RPC will have a "Idle Power Usage" of $0.08/Hr and a 25hp motor will be $0.17. Now I will admit I have no idea what they are using as the cost per KWH in their calculation, but assuming that they are close and I honestly will be lucky to run the RPC more than 5 hours a week, the electrical cost did not seem like a large factor compared to the cost of the initial purchase of the RPC and the eventual cost of upgrading the RPC when bigger machines are added.

Again I will say that I am completely new to RPCs and 3 phase, so please let me know if I am falling for marketing fluff.

Nemesis said:

thermite, thank you for continuing to walk me through this. Valid point that the electricity to run the RPC is not free and that the idler motor is essentially burning electricity into heat anytime that it is running. I wasn't worrying too much about the electricity consumption to this point as I was following the information from both American Rotarty's and North America's websites. Per American Rotary's site "A rotary phase converter, by itself, is in an idle state and draws only the amount needed to keep it energized. This is only a few kilowatts and in some cases is less than a kilowatt. Your true electrical consumption is based on what the load draws. The rotary phase converter is merely a device electricity passes through on its way to your load.". Per North America's website a 10hp motor in an RPC will have a "Idle Power Usage" of $0.08/Hr and a 25hp motor will be $0.17. Now I will admit I have no idea what they are using as the cost per KWH in their calculation, but assuming that they are close and I honestly will be lucky to run the RPC more than 5 hours a week, the electrical cost did not seem like a large factor compared to the cost of the initial purchase of the RPC and the eventual cost of upgrading the RPC when bigger machines are added.

Again I will say that I am completely new to RPCs and 3 phase, so please let me know if I am falling for marketing fluff.

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RPC's can waste a helluva lot more than that. Most especially when lightly loaded, neither truly "idle" nor more heavily loaded. The info is out there, independently of makers with a biased interest.

FWIW-not-much, a DC Drive might waste 5 Watts, full 5 HP+ load, doesn't even need the cooling fans a VFD usually requires. OTOH, Type T DC motors may have only 73% or so efficiency for their turbine-smooth wide power band.

Research also "demand" charges and how they are applied. Start with your OWN utility's billing, not my one. Info may even be online, given they are regulated by a public body, many jurisdictions.

"Back in the day" they were applied to commercial service, only. As our "all electric" as-at 1970s' - community matured, folks added insulation, moved-off radiant baseboard to heat pumps and nat gas, appliances went greener, AC SEER went up, a smidge of solar arrived, and we added programmable temp control aids to be more frugal.

The seasonal peaks and valleys became wider, even as overall KWH per-home went down. A utility still has to maintain the grid to deal with the peak, not average, loads. Where's the money?

So now we have "demand" charges.

That's where the startup cycle spikes the bill. More than you might realize. Research that. Be happy if you are still in the clear, but don't assume it will stay that way.

thermite said:

My residential electric service was "upgraded" a while back. The new meter and bill include "demand" charges.

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You've been a bad boy sometime in your past. Even Con Ed doesn't impose peak demand charges on residential
power, only commercial. And any three phase service is by defintion commercial for them.

If he's using a 25 hp idler to run the 5 hp lathe, he doesn't even need any kind of panel, any kind of capacitor tuning.
Just belt it to a pony motor, run it up, and hit the switch. The monarch will think it's running on utility power. Unloaded,
most of the current drawn by the idler is reactive.

jim rozen said:

You've been a bad boy sometime in your past.

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MOST of it, actually. But that has sod-all to do with the present powerco.

They - and a consortium of US Steel, Singer, GE, et al, screwed the pooch over 40 years ago on a "model" all electric community. NO fault isolation and no proper zoned alarms on the power distribution. Blacksnake chases a rodent into a vault-pig for a fry-up suicide pact, whole damned community goes dark, lights still on, all sides of us.

Dom VA krews in pairs, several trucks worth, start cruising the streets and key home back yards on foot, until Mark One human nose finds the faulted unit. Typically three hours and a bit. Worst outages ran 7 days and 9 days. Underground runs dug-up, frozen ground, parts they couldn't get, dead of a severe winter, whatever.

Daft as the "Aloha" comms alleged-protocol, that system.

Hence the MEP-803A NATO "tactically quiet" diesel gen set and external tankage, my patch. Twin fridge-freezers ain't cheap, gone rotten, nor we elder folk happy with either over-heated or over-cold quarters.

BTW: Demand figure, last two months bills was but 7.92 and 8.66, main difference air-con, three souls whole house over just me, and partial. No significant machinery used above light-duty carpentry saws, that period. Too much else afoot, HKG contingent aboard, to be playing with Old Iron.

On the "to do" list is comparison of Phase-Perfect with RPC on that demand figure.. and more.

Dinosaur Current already the clear winner. 500 ma for the controls at "enable" 5 watts wasted, running flat out, slow-ramp a motor up to speed taking the whole day if that patient.

Interesting job, even fun, but some stubborn bastid or another just has to grit their failing teeth and go see to it.

Obsolete don't mean "useless". Not quite yet. Rate I procrastinate, might never git there, neither.

Everyone, just wanted to say thank you for the help and input. You steered me in a different direction. As luck would have it, a very clean and roughly 4 year old Ronk RPC with a 10hp idler motor showed up on Craigslist 3 hours from me. I was able to pick it up complete with a disconnect panel and outlet for $350. Again, thank you for the help.