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RPC output to Bolt on Phase-a-matic stablizer. American Rotary Output clean-up.

countryguy

Hot Rolled
Joined
Jul 29, 2014
Location
Mich, USA
Hi everyone,

Has anyone placed one of these into their 3phase RPC setup?
https://phaseconverters.phase-a-matic.com/Asset/VSB.pdf
Prices are not horrible if it helps protect a very expensive (to us) machine. Thinking of the 15hp 43A unit. Or... other suggestions?

The details: 3ph AC is not my thing... ready to learn.
Rural setting. 200amp service pole to basement box. Haas VF4/ 98 20HP in the garage via distant 100amp box 75ft away. 6awg to box, new 6awg to RPC. 8 or 10 AWG whip to Haas. Xformer taps in rear on the 244-260 input. a 240 40Gal piston compressor in basement, 6awg into it's own breaker.

Dad/Son start-up. Rebuilt the haas & added American Rotary AD RPC unit. (15hp) in garage next to Haas. Wild-leg on Haas L2 input. spindle spinning/under load. 800RPm.
L1-L2 252.4
L2-L3 256.0
L1-L3 239.5 (my single phase)

American Rotary was called. 2x now. They're not concerned w/ the 16.5 / 12.5 diffs. said it's really up to the Haas tolerances. They did suggest a stabilizer or buck boost if I want to try & clean up power (or flucuations) to the Haas. 16V diff is a bit over 1% the 5% they claim to hold. They had no solution other than an add-on device.

When the unit kicks up to say 4000RPM, or the table is flying around... we'll see the Voltage dip considerably for a in-rush moment or two. 225 229 type L1-L3 readings w/ the meter on the 'lowest - hold' to display the lowest reading observed.

The Son is graduating soon, going to try job-shopping and CAD/CAM services... Going to be important to protect the equipment over time but not waste funds either.

Just wondered what ya'll thought. I did search & read for RPC and Balance and RPC setup posts. Rather technical cap-balance discussions... ??? Over Summer's here we always see lower power and need to move the Xformer taps to the lower settings. (haas offers 4 input range taps based on the power input you present to the unit) Else we get the voltage alarms.

Just some thoughts over coffee... wondered what folks thought. TIA
CG.
 
Without cracking a book, Wire sizes seem on the small side, especially for the length. Find a voltage drop calculator online and play around.
I have a AR10 and have real short runs and use 6.


Sent from my iPhone using Tapatalk Pro
 
Without cracking a book, Wire sizes seem on the small side, especially for the length. Find a voltage drop calculator online and play around.
Or just use the dirt-common charts.

Common 90-degree CEE, not EFF, THHN/THWN et al are only listed to 95 A, lower temp rated jacketing is lower Ampacity yet.

I run #4 Copper for 80 A, buried conduit to the gen set. The "present" gen only hauls 55 A for 10 kVA, so that will do for a someday, maybe 15 KVA and a bit. But NOT 100 A.

That run, here, should have #2 Copper for better "wire and forget" class results.

If I couldn't do anything else on a retired backwoods redneck's budget, I'd double-up the #6.

"Filter" an RPC with nought but extra caps?

Yer load may very well need some fiddle-fart "tuning" of caps, yes.

But unless you have the wherewithal to measure and sort IF even before "how much", I'd suggest adding a supplementary idler is likely to give you better results with less math as to stiffening the derived leg so balance shift under varying load is less problematic to begin with.
 
I can't comment on the device in question, but I do have a couple of phase-a-matic "converters", that I use as starters for home built RPC.

Nothing but a box of caps would be my guess as well.

Now adding a SECOND idler motor on line after the rpc is energized can only improve line to line voltage symmetry.

Stick in a 10 hp motor and check it out. It won't draw a lot of juice just sitting there. ($) You will need some switch gear. Perhaps a Steveco switch and a magnetic contactor. So an ugly box will still be needed as well. Such is life.
 
I can't comment on the device in question, but I do have a couple of phase-a-matic "converters", that I use as starters for home built RPC.

Nothing but a box of caps would be my guess as well.
Goods "exist" that attempt to add or remove capacitance on the fly off the back of sensing the magnitude of the imbalance.

I can't see the switching involved as a "good thing" for a CNC critter's fussy brains.

Supplementary is easier. Just move the run/balance caps, all hands, to the idler side of its contactor, leave the start cap plus-plus on the primary pilot & it's 'legs".

"Reasonably appropriate" approximation of re-balance comes or goes as you add or drop-off idler(s).

No need to be "perfect". A load motor at under 85% or so of "nameplate" doesn't actually CARE as much as all that.

If a CNC's "brains box" IS affected? Look to helping it's PSU do a better job.

Not hard, that. Nor specific to RPC, either. GOOD PSU for 'tronic logic can eat most anything on their plate, block all manner of nastiness as well. Not as if it was a new challenge. Check your laptop's wall-wart.
 
A cheap ugly box with a few run capacitors. A band-aid for their RPC's.


I doubt that.

It was, however, my first thought. As a tie breaker I looked at the weight and size of the units.

It seems pretty likely that it is actually a transformer which is configured various ways to buck or boost the voltage as needed. Presumably, it would include relays to do the adjustment., but that is not a certainty.
 
I run the output from my 40 hp american rotary through an isolation transformer.

I've got perfect 3 phase doing this, and the large transformer acts an "electrical accumulator", so I dont get large voltage drops when starting a spindle at 10000rpm
 
I looked into a Phase-a-matic. Just a start capacitor that stays connected as a run capacitor between two lines T1 and T3. This box handles the T2 to T3 run cap.

Provide a sketch of your connections.
 
Are you saying these boxes are just a capacitor?

They have some heavy-ass capacitors if so...... the big one is over 150 lb.
 
I'm with JST.

If it's heavy, there is an x-former in there.

Same thing though, low tech in a box. x-formers are more "valuable" than caps are "if you need one'.
An additional spinner motor is "more than a transformer" , but on the same order.
 
Are you saying these boxes are just a capacitor?

They have some heavy-ass capacitors if so...... the big one is over 150 lb.

I would suggest that the box is a add-on hack to a hack.

There probably is some iron in there...not the vitamin type.
 
I would suggest that the box is a add-on hack to a hack.

There probably is some iron in there...not the vitamin type.


It may not be a hack, and I don't know what the "original hack" you refer to is......(the "hack" that the "hack-in-a-box" was added to). A boost transformer, or especially an automatically-adjustable-on-the-fly one, is a practical solution.

The RPC INHERENTLY produces a generated leg voltage which is LOWER than the mains voltage. That is the only way it can work. The degree to which it is lower depends on the load that is applied*, which is why oversized idlers work better.

So adding a boost transformer to that leg makes sense, as long as it does not add too much impedance. It would also be possible to add turns (if they fit) to the idler motor on that leg, so that the net would be closer to mains voltage.

What one would want is an unloaded voltage a bit OVER mains voltage, with the voltage falling (due to impedance) to approximately mains voltage at full load. You are stuck, since the only leg with any added impedance s the generated leg, with the motor and possibly the boost transformer in series, where the other two have nothing in series. That makes a perfect balance pretty much impossible as a practical matter.

The usual use of "balance" capacitors is also a bit of a "hack", since its effect is radically changed by loading. The balance capacitor system must be optimized for one particular load. If balanced for max load, it will almost certainly be radically too high for light loads.

* more specifically, the degree to which the idler slows down under load
 
Hi everyone,

Has anyone placed one of these into their 3phase RPC setup?
https://phaseconverters.phase-a-matic.com/Asset/VSB.pdf
Prices are not horrible if it helps protect a very expensive (to us) machine. Thinking of the 15hp 43A unit. Or... other suggestions?

The details: 3ph AC is not my thing... ready to learn.
Rural setting. 200amp service pole to basement box. Haas VF4/ 98 20HP in the garage via distant 100amp box 75ft away. 6awg to box, new 6awg to RPC. 8 or 10 AWG whip to Haas. Xformer taps in rear on the 244-260 input. a 240 40Gal piston compressor in basement, 6awg into it's own breaker.

Dad/Son start-up. Rebuilt the haas & added American Rotary AD RPC unit. (15hp) in garage next to Haas. Wild-leg on Haas L2 input. spindle spinning/under load. 800RPm.
L1-L2 252.4
L2-L3 256.0
L1-L3 239.5 (my single phase)

American Rotary was called. 2x now. They're not concerned w/ the 16.5 / 12.5 diffs. said it's really up to the Haas tolerances. They did suggest a stabilizer or buck boost if I want to try & clean up power (or flucuations) to the Haas. 16V diff is a bit over 1% the 5% they claim to hold. They had no solution other than an add-on device.

When the unit kicks up to say 4000RPM, or the table is flying around... we'll see the Voltage dip considerably for a in-rush moment or two. 225 229 type L1-L3 readings w/ the meter on the 'lowest - hold' to display the lowest reading observed.

The Son is graduating soon, going to try job-shopping and CAD/CAM services... Going to be important to protect the equipment over time but not waste funds either.

Just wondered what ya'll thought. I did search & read for RPC and Balance and RPC setup posts. Rather technical cap-balance discussions... ??? Over Summer's here we always see lower power and need to move the Xformer taps to the lower settings. (haas offers 4 input range taps based on the power input you present to the unit) Else we get the voltage alarms.

Just some thoughts over coffee... wondered what folks thought. TIA
CG.

theres the problem a 15HP vfd powering a 20HP motor.....
the 6Ga at 75 feet is only good for about 55A.
that is what you call voltage drop.
 
I have a Phase-A-Matic model VS-2 on an old Reid Brothers surface grinder . It regulates the voltages across the legs feeding the small 1 hp motor to 1 to 1 1/2 volts difference .

I just looked at the insides and it is a transformer .

I forgot to say this grinder is powered by a rotary phase converter .
 
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Thanks a ton folks! Great dialog here. Some of which I'm new too but learning is half the fun! I ordered some new line copper yesterday. Will get a double up on the #6 as someone suggested. we're looking at running 2 or 4 from the basement box to the RPC unit. We'll sort it out. The #6 from box to box is existing and I'll need to fish and run new to make that happen.
As for 3phase. I would like to explore a bit further if isolation 3ph Xformer would help us? Since we run high ... would a 330 to 330 isolation help (as someone noted works on the dips as 'addative') put in the 340-360 3phase and isloate to a smoother 330out ? I am going to call the phase a matic folks tomorrow. Getting back to this project next. TIA!
 
Been a bit and I wanted to update this thread on updates and events. The Electrical run was replaced w/ a dedicated 2AWG run for the 240 to RPC. 6AWS from RPC to Haas. (12ft). This allowed us to run for many weeks w/o an under-voltage alarm. But the sag on power was still noted around 8-9% (min 5 by power spec I was told?) So I called the power co. to have them come review and service if required. They came w/i a few hours w/ 3 trucks and 5 or 6 guys. Turns out we have a 70's 10KVA transformer running 2 houses with noted drop/sag from their testing. Both the housed have small biz out of the barn/garages. The pole has been issued a Xformer replace ticket! it'll be a 25 or 50KVA depending on some factors. Anyway- In the end, Just calling our SP turned into a positive upgrade for the Kids startup endeavor. Did not need to spend on anything too outlandish and have much better comfort in a production setting in the near future. HAve a great summer everyone. GC
 
^^ Good News.

I will have to get a RPC...probably American Rotary AD. Was curious if I should run an isolation transformer as well. So to others out there and since it is relevant; would the transformer have to be rated the same as the rotary? or...half/normal hp rating?

So for a 20hp Haas....American AD-40+....plus isolation transformer of what size? Have others needed to do this or chose to do this in their backyard shops to protect the machines?
 








 
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