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I am lost when it comes to phase converters

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Forum topic by yellowtruck75 posted 04-10-2014 12:26 PM 1041 views 0 times favorited 19 replies Add to Favorites Watch
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yellowtruck75

424 posts in 1810 days


04-10-2014 12:26 PM

I am interested in purchasing a 12” – 16” used Northfield jointer but I don’t have 3 phase power in my shop. Everything that I have been reading is very confusing. Can a jointer run on a static converter or do I need a rotary converter? What size convereter do I need? I just build my shop 6 months ago and I have ALOT of outlets so taht I don’t have to use extension cords (both 110 & 220), would I need different plugs for the machines running on the converter?


19 replies so far

View Shawn Masterson's profile

Shawn Masterson

1262 posts in 692 days


#1 posted 04-10-2014 12:44 PM

it’s not that hard. What is HP of the motor?? If you go with a static converter you will only get 2/3 of the rated power. So if its rated at 3hp you will only have 2hp. with the static you can mount the converter box right on the machine, then plug it into a single phase outlet just like any other machine. I have seen many machines with static converters mounted inside the base and you would never know they were 3phz if no one told you.

If you go with rotary you will have to have a cord to get the power from the converter to the machine. IMHO I really see no reason that you couldn’t go with a static but is all choise. I would seek out topomax he’s the resident sparky around here.

View bonesbr549's profile

bonesbr549

282 posts in 1810 days


#2 posted 04-10-2014 12:56 PM

Been there buddy. I was sitting in your shoes some time ago. I was purchasing a northfield 18” planer. I’d wired many shops, but never dealt with 3 phase. After all the research the answer to what to get depends on your strategy long term. Some folks swear by static converters, and vfd’s. Some out there say that it will shorten the life of the motor. And don’t even get into the true sine wave argument stuff. There are folks that build their own from capacitor to idler motor.

For me, I wanted a solution that would support my current need 7.5hp, and other machines. I also spoke with Northfield. All the advice from the folks over at old woodworking tools forum and northfield, pointed me to American Rotary phase converters. They are a great product american made, and the power is balanced across the three legs and that’s important. I bought the panel and the baldor 10hp idler motor (generates the third leg) that would support a 7.5hp load (you have to have a more powerful motor than you will actually pull). It works great and support was great. If you have ever wired an outlet from your panel you can do this. If not, an electrician is advised.

You probable could just buy the panel and go buy a used motor off ebay to do the idler function, but I wanted a whole solution that the vendor would stand behind. I’ve been pleased.

One important note! you need to know the voltage of the machine and get the appropriate RPC. I chose to use 3 phase 240v tools since my northfield was wired that way. If the tool is 480v then you need to get the appropriate model. You will find good bargans on 3 phase motors and tools as the market is limited. Mines running like a charm ever since I put it in.

View crank49's profile (online now)

crank49

3503 posts in 1714 days


#3 posted 04-10-2014 01:07 PM

Another solution exists that has not been mentioned.
It is a more modern control called a VFD. (Variable Frequency Drive)
The VFD was created to provide programmable variable speed control, but has the side benefit of being able to convert single phase power supply into a 3 phase output at any voltage and frequency within its range.
Plus, it is no more expensive than the other methods and also provides balanced power like the rotary phase converter.

If you are interested I will provide more information.

By the way, the last post mentioned 408 volt tools but I suspect he meant 480 volt. The standards are 120V, 208V, 240V, and 480V. Some European machines have been brought into the USA with 380V motors but those are pretty rare.

-- Michael :-{| “If you tell a big enough lie and tell it frequently enough, it will be believed.” ― A H

View Fred Hargis's profile

Fred Hargis

2031 posts in 1237 days


#4 posted 04-10-2014 02:14 PM

I agree with Crank, a VFD may be a better option though if it’s a very large motor you may do better with an RPC. I suggest you skip the static convertor. Narrowing these down to a plan and asking more questions would be advisable. Also consider signing up over at OWWM for all kinds of info about that jointer and 3 phase info.

-- Our village hasn't lost it's idiot, he was elected to congress.

View Loren's profile

Loren

7821 posts in 2391 days


#5 posted 04-10-2014 03:36 PM

If the machine is 3hp or under a VFD isn’t too expensive and
is pretty easy to set up. It all delivers full power. There
is some question about long term durability of VFDs in
dusty environments. You also cannot use you machine’s
original switch with a VFD and machines that have
pneumatic components or multiple motors won’t work
with a VFD at all, so that means no edgebanders
or wide belt sanders.

A rotary converter is the better option in my opinion if you
don’t need the speed control and reversing offered by VFDs.
Once you get one 3 phase machine up and running you’ll start
looking at acquiring others, believe me. With a rotary
converter you can run all your 3 phase machines off one
piece of equipment.

I have about $350 into my most recent rotary converter.
A 10 hp motor was acquired from a local ebay seller and
I bought a Panel from Phase-craft. I had to put in a
pair of 50 amp breakers in my my shop panel to
feed the phase converter.

Static converters are inexpensive and easy to set up, you
can use the machine’s original switch and the loss of
operating power may be acceptable. If the 16” jointer
has a 5hp motor, you can probably get by with 3.3.

-- http://lawoodworking.com

View crank49's profile (online now)

crank49

3503 posts in 1714 days


#6 posted 04-10-2014 04:31 PM

Loren makes a good point about the possibility of multiple machines off one rotary converter. Having one of those would be more cost effective in a situation where you have several machines running on 3 phase motors.

And, while the VFDs are available for any size motor, biggest one I ever saw was for an 18,000 hp motor, they do get more expensive proportionately when the motor is over 3 hp. By the way, the owner of that 18,000 hp motor said it cost over $10,000 every time you push the start button.

-- Michael :-{| “If you tell a big enough lie and tell it frequently enough, it will be believed.” ― A H

View Jerry's profile

Jerry

2246 posts in 2290 days


#7 posted 04-10-2014 07:51 PM

Very interesting read. It appears the basis have been covered so I probably will not have much to offer, other than personal experience.

We run 3 shapers 7.5 hp, one planer 5 hp and 1 Blum minipress 1 1/2 hp on our 10 hp RPC. We only run one machine at a time. In the future I intend on putting a single phase motor in the planer. The only downside I see that I am not fond of is having to run my RPC at the same time as the other machines. We used to run our 5 hp Quincy on the RPC but since the Quincy runs all day long in our shop, I elected to swap out the motor for a single phase motor. Back then the RPC ran non stop 8 hours a day. Now it sets quite most of the time.

Then we have one Unisaw that is 3 hp, 3 phase. I ran a static converter because I knew that saw would get used a ton and I did not want to run my 10 hp RPC all the time. The converter was just 100.00 off of ebay and it works great. Also, I understand the whole technical reasons why a 3 phase motor running on a static converter is only operating at 2/3 it’s rated power. BUT, in real world experience, my 3 hp Unisaw running on a static converter will rip anything at any feed rate without slowing the blade while running on the static converter. I can certainly say that I have cut with plenty of 1 1/2 hp motors and my 3 hp Unisaw (technically only 2 hp under static converter) is at least twice or more powerful than any of the 1 1/2 hp table saws. So the loss in power really is negligible and not something a person can humanly detect, at least not I. The only thing that I can see is that when starting my 3 phase table saw on the static converter, it does not pop to full speed in 1/2 a second like a true single phase would, but it does go to full power within about 3/4 of a second :)

So my vote is going with a static converter. You don’t have to hear an RPC running all the time. Static converter will run about 100.00. And I believe the static converter will run your jointer fine.

I would consider the RPC more if you were to run an Air Compressor, or some heavier machines like 7.5 hp shapers or if you were going to have multiple 3 phase machines. But even then, I would keep my 3 hp regularly used machines on a static converter (like table saws).

-- Jerry Nettrour, San Antonio, www.topqualitycabinets.net

View Shawn Masterson's profile

Shawn Masterson

1262 posts in 692 days


#8 posted 04-10-2014 10:56 PM

Here is the 10 hp phase-craft panel I have. Here is how I have it setup. I have mine on a $10 remote, so I can turn it on/off from anywhere in the shop as needed

View yellowtruck75's profile

yellowtruck75

424 posts in 1810 days


#9 posted 04-11-2014 12:32 PM

Would a static converter work for a 7.5 hp jointer? At this time I don’t plan on utilizing multiple 3 phase machines. I know that I would lose some horse power with the static converter.

Thoughts?

View Shawn Masterson's profile

Shawn Masterson

1262 posts in 692 days


#10 posted 04-11-2014 12:47 PM

I don’t see a problem with it. A jointer isn’t a heavy start lead. My 20” 5hp planer was on a static converter when I got it. It worked, but I could tell a difference. I would call the guy from phase-craft. He is the owner/operator, and very nice. If you call him and explain what you have he can advise you on what you need to do it right. I will give you an interesting thought If you put a static on your 7.5 hp jointer it will then become a 7.5hp RPC (rotary converter). By starting you jointer you will be able to pull up to 5hp starting power from the jointer. A RPC isn’t that costly and really is the right way to go.

View Jerry's profile

Jerry

2246 posts in 2290 days


#11 posted 04-11-2014 12:58 PM

Yeah, that might work letting your jointer be the idler motor for other future machines. Just remove jointer belts when using it as RPC. Phase-craft is what I use, he can be found on eBay and is very smart and should be of great help to you. Give him a call, he is easy to find and get a hold of.

-- Jerry Nettrour, San Antonio, www.topqualitycabinets.net

View Matt Rogers's profile

Matt Rogers

48 posts in 713 days


#12 posted 04-11-2014 12:59 PM

To Shawn’s post – You are correct that the jointer would then backfeed three phase starting power to enable another machine to run, however if running both machines in series, you would have to correctly size the wires, breaker, switches, etc all the way back to the panel to accommodate the new load. That would most likely require running all new wiring when you went to hook up that new motor. 12.5hp of three phase motor could pull 42 amps three phase, which would require 74+ amps of single phase current. So your single phase feed wires would need to be huge.

-- Matt Rogers, http://www.cleanairwoodworks.com

View Shawn Masterson's profile

Shawn Masterson

1262 posts in 692 days


#13 posted 04-12-2014 03:33 AM

Matt Rogers I believe you are right, but not exactly. An induction motor rated at the FLA is not using the FLA unless it is being worked. I have tested this when I was setting up mine. My RPC only draws 2-3 amps running idle. For example my planer draws around 11 amps per leg. you are only drawing on 2 legs and adding the draw of the RPC you are still under 25 amps. A motor idling with on load draws very little amperage. also I have never seen a 12.5 hp electric motor, I am a little lost in where you came up with 74 amps of single phase power. I know a 15hp 3phz motor could pull around 42 amps, but if you are getting into hp like that I doubt you would be doing it in a hobbie style shop. Please advise me I am trying to see your point of view, as I am still learning along the way. Thanks.

View Loren's profile

Loren

7821 posts in 2391 days


#14 posted 04-12-2014 04:07 AM

7.5hp is hella power for a 16” jointer. Reduced by 1/3rd
it’s still a beast.

-- http://lawoodworking.com

View Joseph Jossem's profile

Joseph Jossem

408 posts in 1012 days


#15 posted 04-12-2014 04:24 AM

i run a 16” scmi jointer with rotary convertor i can run multiple tools at once lorens right my jointer is 6hp

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