Digital or Rotary Phase Converters?

RFC can run several machines. easy set up, takes more shop space.
VFD can run two motors No big amp draw to start up your motor.( starting amps is the same as free running amps ) they are compact. you can electrically brake the motor when you stop it. you get variable speed. more complicated set up ( if you are not into electronics and computers. buy a quality one with good factory support like an automation house with a on staff tec to help you out.
 
I think all arguments have been made; comes down to equipment usage, equipment type, and cost. My experience/2c:

I have a 15hp RPC from American Rotary Converter, 2hp knee mill, and 3hp VS lathe. Only run 1 machine at a time (yes: the RPC is overkill for what I have; it just happened to be part of the package when I bought my knee mill). I expect two more 3-phase machines in the near future: a SG and 2x72 BG. And at some point I could see a second 3-phase lathe and/or drill press.

I hate how loud the RPC is. But in fairness: its running a user-supplied idler (it a Marathon Electric motor); likely not as quiet as what American ships. Also seems wasteful also from a cost perspective due to being over-spec'ed and that its always running even when machine use may be a small % of run time. I think this RPC-to-Equipment runtime ratio is likely true of many hobbyist use-cases. However, I love having the fact that adding more 3ph equipment or test motors is very convenient - just plug it in.

I think VFD is great, particularly for speed control (lathe, belt grinder...DP/Mill if you have manual pulleys) and quick braking capability (lathe). But they are a paired solution (VFD per each machine) so not as flexible and cost can add up if expecting a few machines.

For me: The easy availability of 3ph w/ a RPC/PP beats out VFD. I think I'll be going to a smaller (10hp) RPC with an outdoor idler to address my noise concerns. Haven't ruled out a digital Phase Perfect though. I need to understand my operational cost of the RPC vs. digital PP. I don't expect a break-even for the PP, but am curious what the different in operational cost is. I like the idea of low-noise PP and that it takes much less power when idle.

And that said: I still will need 1 or 2 VFDs. I definitely will use one for the BG. And while it would be nice to outfit a lathe with a VFD at some point, that's not as critical. So my logic is that the RPC/PP at least ensures I have no limitations w/r/t 3ph equipment, but means I'll miss out on some VFD-related features for certain equipment.

So - buy both. Haha. How's that for a solution... I'm not helpful at all!
 
Phase Perfect (PP) idle dissipation is probably around 20-30W (5-7.5Hp models, their 30Hp model is 75W), similar to a VFD (efficiency is around 98%) a 15 Hp RPC consumes around 600-800W (2.5-3.5 @230VAC) at idle, you also do not have the limitations of the high start up amps of say a 10-20Hp RPC. A 5 Hp Phase Perfect can be run off of a 40 or 50A circuit breaker, a 15 Hp RPC minimum would be 60A if not larger, you also have the additional expense of heavier wiring and cost of relocating the idler if you are putting it outside (so I would figure another $100-200 in wiring costs). You do not have the issues of output voltage line to line imbalance depending on load with the PP. Comparing the cost of a PP PTS-005 ($1332) vs. a North American RPC PL-10 with an outdoor rated motor ($1249 plus shipping) both rated for running a 5Hp 3 phase motor, I can't really see any benefit to going with an RPC vs. the PP if one is looking at turn key type RPC's.
 
I didn't bother going into incidentals like wiring, but you're absolutely correct that it adds up. In my case I have the wiring already place due to the large RPC and existing exterior panel which would make easy work to wire the outdoor idler. But someone starting from scratch should factor it in - opening walls, wiring, 3ph distribution panel, etc...can add up big-time.

Do you know if PP ever runs major sales? The RPC from American was appealing because once a year they have significant discounts on top of S&D/refurb. But by MSRP: you have a point, though I also didn't mention simplicity/reliability...but that's a bit harder to quantify.

While here: couple Q's about PP
  • Any value to the hobbyist for the PP enterprise vs. simple? 7.5hp models. The couple things that caught my eye between the two are regen loads (not applicable unless I have braking added to my lathe) and surge protection.
  • Does the optional on-off switch only disable the 3ph output or does it totally shutoff the PP (ie. no current draw)? I get the sense that its the former; if so, I assume a separate service disconnect would be ideal between the PP and breaker panel? Or do folks just leave PP on?
 
I am another very satisfied Phase Perfect user. I ran a Willett Add-a-Phase (a commercially made rotary phase converter), it was fine. The start capacitor timer gave out after about 30 years and was easy to fix. I changed to the PP because I bought a good sized VMC. Of course I moved all the power over to the PP. The PP has been running about 4 years, it is awesome - motors that didn’t start as well are really nice and snappy now.

The Phase Perfect, while it is an electronic phase converter, it is nothing like a VFD.

The only drawback I see on the PhasePerfect is the price. If you can get a PP at a price that is similar to the rotary unit you are considering - then get the PP.
 
keeena said:
I didn't bother going into incidentals like wiring, but you're absolutely correct that it adds up. In my case I have the wiring already place due to the large RPC and existing exterior panel which would make easy work to wire the outdoor idler. But someone starting from scratch should factor it in - opening walls, wiring, 3ph distribution panel, etc...can add up big-time.

Do you know if PP ever runs major sales? The RPC from American was appealing because once a year they have significant discounts on top of S&D/refurb. But by MSRP: you have a point, though I also didn't mention simplicity/reliability...but that's a bit harder to quantify.

While here: couple Q's about PP
  • Any value to the hobbyist for the PP enterprise vs. simple? 7.5hp models. The couple things that caught my eye between the two are regen loads (not applicable unless I have braking added to my lathe) and surge protection.
  • Does the optional on-off switch only disable the 3ph output or does it totally shutoff the PP (ie. no current draw)? I get the sense that its the former; if so, I assume a separate service disconnect would be ideal between the PP and breaker panel? Or do folks just leave PP on?
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I use the remote on/off feature on the PP. Yes, it does completely shut the unit off. I added a surge protection device on the input side of the PP (per the PP supplier recommendations).

”Any value to the hobbyist?” I am a hobbyist, I find the PP great.

I have never heard of the PP products going on sale. In my area it is extremely rare to see a second hand PP come up for sale, but used rotary converters are pretty common. The PP are not as plentiful and once someone buys one, they are unlikely to downgrade until the entire shop is sold off.
 
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Chipper5783 said:
I use the remote on/off feature on the PP. Yes, it does completely shut the unit off. I added a surge protection device on the input side of the PP (per the PP supplier recommendations).

”Any value to the hobbyist?” I am a hobbyist, I find the PP great.

I have never heard of the PP products going on sale. In my area it is extremely rare to see a second hand PP come up for sale, but used rotary converters are pretty common. The PP are not as plentiful and once someone buys one, they are unlikely to downgrade until the entire shop is sold off.
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I ended up buying the phase perfect simple 5Hp for my Bridgeport. I think it was 10 percent off for Black Friday/cyber Monday but I don’t remember exactly. It’s running great so far and very quiet. I only have one hour of run time on it so far though.
 
I used a 10hp Phase Perfect at my old house to run my cnc mill. I was told that it was the only way to go, because the 3 phase coming out is very clean and is balanced within a few percent. When the replacement boards in the cnc are in the thousands I didn't want to take a chance with poor made up 3 phase. When I moved into my current shop that has 3 phase I sold the Phase Perfect within a day for pretty much what i purchased it for ! I would highly recommend a PP for a CNC or if you are going to run more than one 3 phase machine, think of it as your own power company supplying 3 phase to your shop.
 
Here’s another opinion: I run a Bridgeport, a Takisawa 14” lathe, a big Jet vertical bandsaw VBS-900 and a 16” Kalamazoo horizontal saw all on a $150 Phase-a-Matic static converter. The tools are all between 1 and 3 HP, how the converter is specified. They are all wired in parallel, through twist lock plugs/sockets. Works fine.

People argue you only get 2/3 power…but you get 100% of what the equipment needs up to the 2/3 point. In many years of operation, I have yet to encounter a power limitation on any of these machines. I can make all the blue hot chips I want. You can also run two machines simultaneously, works fine. It’s just me normally, but friends come by occasionally and we might both be doing something.
 
Winegrower said:
Here’s another opinion: I run a Bridgeport, a Takisawa 14” lathe, a big Jet vertical bandsaw VBS-900 and a 16” Kalamazoo horizontal saw all on a $150 Phase-a-Matic static converter. The tools are all between 1 and 3 HP, how the converter is specified. They are all wired in parallel, through twist lock plugs/sockets. Works fine.

People argue you only get 2/3 power…but you get 100% of what the equipment needs up to the 2/3 point. In many years of operation, I have yet to encounter a power limitation on any of these machines. I can make all the blue hot chips I want. You can also run two machines simultaneously, works fine. It’s just me normally, but friends come by occasionally and we might both be doing something.
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That is what I have. I have it wired for a receptacle. I just have a wired cord on my Tree mill and one on my SB9. As I never run both at the same time. I have zero issues. I have had the mill and Phase-a-Matic for close to 30 years now.


Cutting oil is my blood.
 
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