Short Term, Budget Friendly, 3 Phase Options

Help me with this, folks! This issue of only getting 2/3 the power is overblown, in my opinion. You get all the power the equipment asks for, up until it needs more than 2/3 power. What happens beyond that is a bit unclear, seems like some winding currents would maybe go beyond design ratings for a bit, but really, what is in the phase converter that's a problem?...the power comes from the normal single phase line, that really doesn't have a HP limit, if you've sized the wire and breaker correctly.

I power my Bridgeport mill, 1.5HP, the Takisawa lathe, 3HP and the Kalamazoo saw, ? HP from one 1 to 3 HP phase converter. I literally have never experienced anything that seemed like a power limitation.
 
Technical Ted said:
I have a vari-speed 2HP Bridgeport at well. I run mine from a VFD and am glad I do. There are many times when hi range is a little too fast and rather than switching into low range I simply slow down the VFD. To be honest, I can't even remember the last time I dropped into low range...

Another consideration is you might end up with a flat belt drive lathe, like a South Bend, and I REALLY love having the VFD on mine! It really comes in handy being able to tweak the speed on the fly. I have a single phase motor on my larger SB 15" and it's not nearly as nice to run.

Just a couple of things to consider before you make a decision.

Ted
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I have a flat belt South Bend 13", but it was converted to single phase 220 by the previous owner. What I am hoping to find is a replacement some day for it, something like a nice Monarch (not a 10ee), Pratt & Whitney, LeBlonde, etc. - but those are future plans.

What VFD are you using?
 
Winegrower said:
Help me with this, folks! This issue of only getting 2/3 the power is overblown, in my opinion. You get all the power the equipment asks for, up until it needs more than 2/3 power. What happens beyond that is a bit unclear, seems like some winding currents would maybe go beyond design ratings for a bit, but really, what is in the phase converter that's a problem?...the power comes from the normal single phase line, that really doesn't have a HP limit, if you've sized the wire and breaker correctly.

I power my Bridgeport mill, 1.5HP, the Takisawa lathe, 3HP and the Kalamazoo saw, ? HP from one 1 to 3 HP phase converter. I literally have never experienced anything that seemed like a power limitation.
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Perhaps you are correct. But I would rather have it and not need it (if I can afford it) than need it and not have it.
 
Winegrower said:
Help me with this, folks! This issue of only getting 2/3 the power is overblown, in my opinion. You get all the power the equipment asks for, up until it needs more than 2/3 power. What happens beyond that is a bit unclear, seems like some winding currents would maybe go beyond design ratings for a bit, but really, what is in the phase converter that's a problem?...the power comes from the normal single phase line, that really doesn't have a HP limit, if you've sized the wire and breaker correctly.

I power my Bridgeport mill, 1.5HP, the Takisawa lathe, 3HP and the Kalamazoo saw, ? HP from one 1 to 3 HP phase converter. I literally have never experienced anything that seemed like a power limitation.
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I too have never experienced a situation where I felt that my 2 hp mill was not delivering enough power. I'm sure that, if you had two equal machines side-by-side, one powered by an RPC and the other by an SPC, you might be able to find a point where the one with the RPC would pull a cut that the SPC powered (actually just started) would not.

For reasons that have not been determined, my 1 hp SB Heavy 10 will not start properly with the SPC. When I need the lathe, I disengage the spindle on the mill and start it. The mill functions as an RPC and I can use the lathe normally, including instant reversing. Once the mill is started, the SPC does not come into play. Instant reversing is something that does not function properly with an SPC. When power tapping on the mill, I have to stop the spindle before reversing. Otherwise it continues to rotate in the same direction.
 
I use this VFD ($90) for my 1.5 HP Bridgeport.

That model claims to work for up to 2hp, but there is a step-up model for an extra $10 that'll work for 3hp

I don't use any of the available speed-change controls for it, just use it to get 3-phase.

Couldn't be happier with my purchase.

Installation / setup was easy. I locked it in a cabinet behind my Bridgeport 2.5 years ago and haven't so much as looked at it since.
 
Taken from the wolf automation website.

Digital Static Phase Converters​

These straightforward units start your application with a 3 phase load but then switch to single phase power.
This is done through circuitry disconnecting after start-up and subsequently limits the load to about 2/3 of its rated capacity. This does effect your selection depending on how you intend on running your motor. Applications which require a high torque start-ups but not consistently high HP, such as drill presses, milling machines, and table saws, work best with Digital Static Phase Converters.
 
I have a 1 1/2 HP Bridgeport that's been running on a static converter for nearly 20 years. Like others I've never noticed a lack of power. There have been weeks it's run between 40 and 60 hours or more with no ill effects. Even on the longest running weeks the motor is barely warm to the touch. This machine is running on a Phase A Matic PAM 300HD. It cost about $125.00 new. Today they run a little over $230.00

I have 3 other machines running on static converters. A Sheldon MW-56-P lathe (2hp), a Racine 66W2 power hacksaw (1.5 hp), and a Black Diamond drill grinder (1/3hp). The Sheldon and the Racine are using American Rotary brand static converters. The Black Diamond is on a North America brand static converter.

I have been very happy with all the converters. The American Rotary's cost about $80.00 new and carry the same lifetime guarantee as the Phase A Matic. American Rotary quit building static converters under their name about 5 years ago. I didn't realize it at the time, but I believe they had already discontinued production when I ordered the one for my lathe. It should have dawned on me that they were liquidating inventory since it only cost $60.00 with free shipping. They bought out North America at the time and transferred all the static converter business to that name.

I have the same model on my power hacksaw as NCjeeper is using on his mill. I would love to find another for a future machine, but since they haven't been made for several years it's unlikely, I'll find one at a good price
 
Technical Ted said:
I have a vari-speed 2HP Bridgeport at well. I run mine from a VFD and am glad I do. There are many times when hi range is a little too fast and rather than switching into low range I simply slow down the VFD. To be honest, I can't even remember the last time I dropped into low range...
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At the bottom line, a Rotary Converter is a three phase motor with proper [for the size] capacitors. And possibly a little extra for a "kicker" to get it started. I personally avoid any 3 phase equipment so that I am not dependant on another contraption to run my shop. With that said, I am generally in favor of 3 phase if it is readily available. A 3 phase motor can be run simply by adding capacitance to generate the third leg. That is all a Rotary Converter does. Plus being pre wired and with a good enclosure. And sometimes other "bells and whistles".

A "Variable Frequency Drive", aka a VFD, converts the incoming line to DC and electronically generates a 3 phase output. Depending on the quality of the VFD, this can vary from a (near) square wave to a (near) sinusoidal output. A good quality VFD will naturally be more expensive than a low end drive. But price is not necessarily a good indication of quality. There are some limitations to a VFD, not the least that one per motor is required. But on the up side, speed of that motor can be easily varied from 50% to 150% without noticable loss of power from the motor. When all the drive is powering is a reactive load (motor), even a square wave is magnetically rounded off.

If the deciding factor is cost alone, try a few motor starting capacitors from one side of the line to generate the third leg. If more $$ is available, I personally would recommend a VFD over a Rotary simply for the variable speed aspect. There are down sides to any "fix", it is a "band aid" by another name. From bringing in 3 phase power to the lowest conversion, there will be a cost. The individual must make the final call as to which cost is the most acceptable.

.
 
Bi11Hudson said:
At the bottom line, a Rotary Converter is a three phase motor with proper [for the size] capacitors. And possibly a little extra for a "kicker" to get it started. I personally avoid any 3 phase equipment so that I am not dependant on another contraption to run my shop. With that said, I am generally in favor of 3 phase if it is readily available. A 3 phase motor can be run simply by adding capacitance to generate the third leg. That is all a Rotary Converter does. Plus being pre wired and with a good enclosure. And sometimes other "bells and whistles".
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I think this is an oversimplification. A good quality rotary phase converter generates the third leg because the "motor" isn't a motor, but an induction generator. It's not just a motor and some capacitors. Capacitors don't generate anything. They store potential. The only reason they "work" is that the stored potential in the capacitor simulates a third leg getting the motor started. Once the motor is started, inertia takes over and it can be run on just the two legs. The third is essentially dead since there is never enough potential in the capacitor anymore. It's all going to the other two legs. I know my electronics - by no means an electrical engineer, although that was my major in college before dropping out to join the military.

Also, some would argue, although I have not seen any evidence of it being fact, but can understandably see the possibility, is that a 3 phase motor, when properly powered by 3 phase power, will be more stable, especially at high torque, resulting in a cleaner surface finish.

Regardless, I have no desire, even though capable, of building an RPC or just throwing some capacitors on high voltage lines. I am willing to give the VFD or SPC a try, especially if it's affordable, and not feel I wasted my time or money.
 
My 2 hp Bridgeport has stalled several times while hogging with a 3" face mill and with the larger S&D drill bits. It is powered with a 5hp rpc. I wouldn't consider powering it with a static converter.
 
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