American Rotary ADX 25 converter and 20hp Powerturn

One month ago I upgraded from a 15hp to 25hp American Rotary ADX phase converter. I upgraded to accommodate a 10hp planer that I will be running in tandem with a 7.5hp dust collector.

I don’t even have the phase converter wired up yet and two weeks ago I made a deal on a trailer queen Lodge & Shipley 20hp Powerturn ($40,000 rebuild 10 years ago and only light use after the rebuild). I won’t be running the lathe simultaneously with any other large 3 phase loads, but am concerned about what I should do to ensure good operation of the lathe.

What is the best path forward? I will probably never take a 20hp cut with the lathe, but the power meter is initially pegged when the clutch is engaged at higher speeds.

I plan to check in with American Rotary, but am curious regarding what others might recommend as it seems like the converter might be marginal at best, even if I spin up my 5 hp table saw or other similar load before starting the lathe.

I would say use both converters when turning it on. 25HP I would think might be right at the edge of its capacity. you could try it and see what happens. if more is needed, just add another RPC and turn that on when you need it.

So.... is that a 25 HP IDLER or a 25 HP starting capability?

AR wants you should get an ADX 50 to start a 25 HP

BT Fabrication said:

I would say use both converters when turning it on. 25HP I would think might be right at the edge of its capacity. you could try it and see what happens. if more is needed, just add another RPC and turn that on when you need it.

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If I still had both that would be a good idea. Unfortunately for me, I gave the 15 to my son to keep in the farm shop.

johnoder said:

So.... is that a 25 HP IDLER or a 25 HP starting capability?

AR wants you should get an ADX 50 to start a 25 HP

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Idler, I wish it was the starting capability.

I say get yourself a contactor and a surplus 15 HP motor. Fire up your ADX25, hit the relay on the 15HP, and then go to town on the lathe. If you find you're out of voltage balance, install caps on the motor side of the contactor you added. I'm assuming you know about capacitor safety. Nice find on the lathe! L&S are nice machines.

AndyF said:

Idler, I wish it was the starting capability.

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What ever' body else has already said . but...

... your HARDER to meet challenge is likely to be not enough single-phase service Ampacity, back of it all, to cover the Large & Shapely's starting inrush, even with supplementary idlers, progressively brought online?

Just a SWAG, but my guess is TWO 15 HP supplementary's ....to put enough RPC electrical and rotational inertia ahead of it to get the L&S turning.

First.. "not wired, yet" y' said?

.. you need to make sure your service is comfortable with even the start of the 25 HP idler.

"If not so much?" You might need to "pony" spin-up the L&S load-motor before dropping it onto the RPC.

"Running it" isn't as hard.

2CW

The usual issue with a too-small "idler" is that the generated leg does not hold up under starting loads. Adding idlers "can" help that.

It comes with a cost, however. Several smaller idlers normally draw more power from the source than one large-enough idler.

So, IF you have limited source amps, an "idler farm" is likely not the way to go.

Each idler draws two currents. One is the current necessary for driving the rotor to generate the "generated leg" power. The other is the magnetizing current for the idler itself.

You can see this from the current draws of different motors. A single phase 1 HP motor draws about 8A at 230V, while a 2 HP single phase motor draws 12A. Similar current differences are seen in 3 phase motors.

So two motors of the same lower HP would (obviously) be expected to draw double the current of a single one, while a single motor of double the HP will only draw around 1 1/2 times the current, or a bit more.

If you are limited in source current, you are better off with the required total HP of idler in one piece, as opposed to several.

Naturally, if the source current is not limited so much, you can take your choice of approach. The multi-idler setup allows less current draw for "normal" loads that the basic RPC can handle, you simply switch off unneeded idlers.

AndyF said:

One month ago I upgraded from a 15hp to 25hp American Rotary ADX phase converter...

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Add 1 more ADX 25.

JST said:

If you are limited in source current, you are better off with the required total HP of idler in one piece, as opposed to several.

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No. That is NOT always the case, nor even necessarily the majority case.

An "idler" is exactly what it says it is. It isn't MEANT to draw nameplate FLA for its own CONSUMPTION. And "in use", does not.

What it DOES do, however, is momentarily draw a very high starting amperage - because two of its 'expected' three phases are ABSENT.. and must be 'faked" with the assistance of a start cap. or manual or motorized "pony" spin-up.

With progressive start of multiple idlers, the starting load impact - first, of each successive idler itself, next, of the load-motor(s) - becomes progressively EASIER to manage. Not harder.

Is it less efficient overall?

Surely it CAN be.

However...

The multi-idler setup allows less current draw for "normal" loads that the basic RPC can handle, you simply switch off unneeded idlers.

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THIS!

And with the "run" caps on the motor-side of its contactor, your balance is being adjusted to the loads in the same go.

So... I gain BACK:

- the ability to drop one or more supplementary idlers OFF the line once the heavy load motor has been started and drops to a MUCH lower power draw in actual use.

- the ability to easily select for no more idler - OR BLANCE CAPS - than needed for (in my case) wide needs range from as little as 1 1/2 3-Phase motor HP to as much as 10 HP as multiple-motor, single-machine HP .. not even ONE of my load having any sort of a clutch to start unloaded.

"Revenue" shop?

Well. for openers, those are more likely to have either a 200A service NOT shared with other facilities .... ELSE a 400A single-phase service.

My modest 1970's-vintage "nominal" 200 A 'residential' suburban service?

Is it really "200A"? Not b***dy likely...given it is shared off a transformer with four other "200A" each residences!

The OP? Wise to look back up the grid he is on ...before jumping into too large of a single-idler rig.

What is the best path forward? I will probably never take a 20hp cut with the lathe, but the power meter is initially pegged when the clutch is engaged at higher speeds.

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You also could just put a 10HP motor in the Powerturn. Find one on Ebay of the same number of poles (rpm), and ideally the same frame size. More likely you find one of a smaller frame size, but it's simple to build an adapter plate. That's how I handled my large lathe.

thermite said:

No. That is NOT always the case, nor even necessarily the majority case.

An "idler" is exactly what it says it is. It isn't MEANT to draw nameplate FLA for its own CONSUMPTION. And "in use", does not.

What it DOES do, however, is momentarily draw a very high starting amperage - because two of its 'expected' three phases are ABSENT.. and must be 'faked" with the assistance of a start cap. or manual or motorized "pony" spin-up.

..........................

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OK, you DO know that what you stated is almost irrelevant, right?

The start current thing is just an issue with all motors, it's inherent in the very high slip at start.

Where it does become an issue is when the idler cannot supply enough current to the generated leg to spin up the load motor fast enough.... so that you pull a lot of current FOR A LONG TIME.

An idler WILL NOT DRAW nameplate FLA..... WHY? Because it does not produce nameplate power. Its power output is via the generated leg, and that is 1/3 of nameplate.

What does an idler draw? It draws its basic magnetizing current, PLUS whatever power it has to supply on the generated leg. Magnetizing current is usually around 40% of FLA for smaller motors. Can be more when running a 3 phase motor on single phase.

You get a "discount" on magnetizing current per HP with a bigger motor. That is why a 2 HP motor draws less than double what a 1 HP draws (for example). A motor that pull 8A at rated power will have 3.5 or so A of magnetizing current. A motor of double power may pull not 16, but only 12 A. Yes, that is FLA, but remember some of that is UNCHANGING, it is magnetizing current. How much depends on power level.

So, if you have one larger vs several smaller idlers, the larger is going to draw less current from the source at the same load.

A slow start can end up having the total draw exceed the breaker for long enough to cause issues, especially since a residence may have a sub panel for the shop, which is often lower current rated than the mains. And because the sub panel breakers may be pre-heated by the draw of whatever you were doing before firing up the big load.

Just something to remember if you have limited source power. Anyone at a "residence" likely has limited power, and even industrial users with 3 phase may not have much better power.

Yah.... residences with "200A service"..... Supplied by a drop that may be 8 Ga copper, or an equivalent aluminum spiral drop. And, supplied along with other residences (usually 2 to 4 others), from a pole transformer rated at possibly 50kVA. That means about 200A total shared between all the residences, and supplied through small wires.

One place I worked had 100A 208V 3 phase, supplied from three 15 kVA single phase transformers, AND shared with a manufacturing facility across the road. We could get 100A, for a little while.

JST said:

OK, you DO know that what you stated is almost irrelevant, right?

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I've heard that "almost" only counts in a game of whore's shoes, J.

OP should assess his service power. That IS "relevant."

"Four-Ought" wires on my one, Shiney-wood, not proper-Copper.

But.... my whole community was built as a "showcase" to tout "modern all electric" homes .. and back in the day of single-glazed windows, thin exterior doors, silly-marginal insulation .... and sore greedy all-incandescent lighting and heavy, inefficient appliance loads.

KWH costs having gone steadily upward, lo these many years, all the improvements in insulation, better windows and doors, more energy-effective lights and appliances, heat pumps rather than baseboard electric, gas heat & cooking, etc. etc. ... to ALL the homes served....

... means more capacity is now "there" for my needs - no others having home shops nor anything else remotely as greedy as it was at the dawn of the 1970's.

Cost have gone up even so.

But my KWH had gone DOWN .. before kitting-out the "shop".

His environmant will be "relevant" to wotever HE has.