Rotary Phase Converter Question for Newbie

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bnelson1980

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I've order the parts to complete my Sharp LMV 50 Mill. The 3HP 3 Phase motor arrives next week. I called American Rotary to order a Rotary Phase Converter. I almost pulled the trigger, but wanted to check with you all to get your advice and make sure I am not going overboard with what American Rotary is saying I need.

They said that because it's a 3HP 3 Phase Mill I would need there 7.5HP AD Rotary Phase Converter. I also need the 3 phase breaker which is $99 and a couple other plugs and receptacles. Comes out to almost $1,200 for the Rotary Phase Converter setup. Seems kind of high to me? If that is what I need, then I will buy it. I just want to make sure I am not being taken advantage of.

Thanks!
 
American rotary is a good honest company, and he is correct about needed a larger 3 phase motor than 3 hp you are going to run. I am not electronic guy but I made my own set up 15 years ago with capacitor and relays I used in the Air Cond. job. but for the last one I just hooked up a static phase converter for about $100 and put that on my my 5hp motor I already had for my 3 phase Bridgeport mill. BUT you are dealing with the right place to buy everything with quality and knowledge of the subject.
 
I usually select an ideler motor at 150% of the largest motor I am going to start... which it seems like a RPC with a 5hp should be suffient. Nothing wrong with stepping up to a 7.5 though.

I usually ebay surplus contactors, breakers, plugs, recepticals, etc. Which usually saves a lot of money. If you are not comfortable with hunting down your own components $99 retail on a breaker does not sound outrageous to me.

Personally I prefer VFD's if the machine only has 1 x 3ph motor.
 
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Sounds like overkill to me; there is no significant starting load with a machine like that and you will likely never use the 3 HP; I'd look at a 5 HP unit. I too made my own phase converter with a motor not significantly larger than my biggest machine motor, used a static converter to start it and oil filled capacitors to balance the phases.
 
You might also consider a VFD, the Teco L510-203-H1 is $200, the Hitachi WJ200-022SF is $320 and you could simply wire it for 2 wire control or 3 wire control. As far as RPC's a 5Hp should be able to start/run a (unloaded) 3 Hp motor, it is not a big load, American Rotary says 2.5Hp for their 5Hp. Other RPC manufactures state a 5Hp RPC (PL-5) can starts a 3Hp light to medium load motor. The 7.5 Hp RPC below is $630. You could also purchase a control panel and get a good motor for less.

http://dealerselectric.com/L510-203-H1-N.asp
http://www.northamericaphaseconverters.com/
http://www.northamericaphaseconverters.com/shop/category/pro-line-rotary-phase-converters/
https://www.ebay.com/itm/American-R...1-3-Three-PH-Heavy-Duty-CNC-USA-/370755610715
 
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Rotary phase converters are easy to build up so that is what I did. Used three phase motors are easy to come by quite cheaply.
I spent maybe fifty dollars on the RPC setup and the money I saved went for tooling. It's all in how you want to play the game
in this hobby I guess.
 
They have 3 different series. The one on ebay for $630 is the most basic series which is the AR-Pro Series. American Rotary says I need the AD Digital Smart Series. I would like to know if I really need that AD -Digital Smart Series or if I could just buy the AR-Pro Series 7.5HP for $634?
 
I do not believe your Sharp mill is a CNC machine... I see no reason that you would need the "Digital Smart" series RPC.

Are you familiar with VFD's (Variable Frequency Drives)? Is there a reason you do not want to use a VFD? Does your mill have power feeds on the table that are 3ph?
 
although i think a 5hp should be just fine i would still go with 7.5. never know what the future brings and there probably is not much difference in price. my 7.5 runs all my machines but one. and up to 5hp

building one is much cheaper if you feel comfortable doing that. i built a 20hp for around $500. i was lucking finding the motor tho'
 
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