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American Rotary ADX10 can it run a 7.5hp design B motor?

rls1160

Plastic
Joined
Feb 4, 2023
He everyone,

I know alot of folks are running AR ADX10 units. I know the recommended max HP on this unit is 5Hp.

Have any of you been able to to push you ADX10 to 7.5hp? I have reached out to American Rotary tech support on this ad well.

I am looking for input from users on wether these devices can be pushed a bit. I am looking to run a 7.5HP design B induction motor. In my research a 7.5HP Design B motor draws less startup Kwa's than smaller HP motors.

Not understanding all the detailed motor electronics itbseems like the robustness of an ADX10 coupled with a design B 7.5hp motor may acually work.

Any actual experience from users of AR ADX10 that have had any experience running a slightly oversized motor woukd be much appreciated.

Thank you
Rick
 
Well I have a ADX20 might just be a AR20 or something. I don't recall, a 20hp RPC from American Rotary. I run a 20hp Monarch Series 62. It's no mill so it has to spin up a bunch metal to get going. It takes a few seconds and I have to hold the button until I can hear it catch, usually after about 2 or 3 seconds then it works fine. That said, I doubt it would like it if I tried to take a 20hp cut. But on this lathe that would be an epic cut, so not something worry about.

So depending on the type of load and that you use wires that will not be a restriction on the load it should work. YMMV.
 
Bill and Richard, i dont have the electrical background to say wether either one of these approaches is viable.

I picked up a 5hp 3p moyor today. I will design around the 5hp and upgrade to 7.5hp if I can make it work with my existing ADX10 converter.

Rick
 
Thank you Gearclash,
My impression is that these convertors can handle a bit more than what their ratings are just based on standard safety design factors.

The manufacturers response was that they don't recommend runing any more than a 5 hp motor on a 10hp RPC. Although it may work, overtime repeated overrated starts could harm the capacitors. Its exactly what I expected the response to be.

Not having much experience with RPC's and 3-phase equipment. I have no real world experience using these devices and how they actually perform in real world situations.

Rick
 
If you use an RPC too small for the load you are connecting to it with, maybe the start caps will kick in when you start your machine tool, because the applied load draws down the RPC too much. That is the only way I can see caps wearing out. Being an engineer, I ask "why" a lot, especially when someone tells me something that does not make sense. Usually they can not explain it any better. And then I know it is likely BS.

-D
 
I have a Ronk RPC rated to start 5 hp motors and it will start an 8 hp motor.
Ronk made some cool static converters, or motor starters.
They had caps to balance the high phase, between the generated leg, and one incoming leg, and they also had a tapped auto transformer (inductor) to balance the low phase, between the generated leg and the incoming leg.
Maybe I got that high and low confused, but you know what I mean. Caps on one phase. an inductor on the other. These seemed to balance out very well, and you had almost zero buzzing from the motor you were running with it. I had one, and it was very heavy because of the transformer. I don't think they make them anymore, at least not like that. But it seemed like a smart product.

-Doozer
 
I have a question about phase converters I believe you guys can help me with.

I have a 7.5hp motor I need to power. I found a 15hp rotophase, but the trash says 5hp max motor. I've been of the understanding that a converter twice the size of the motor to be powered is all I would need.

Is there a reason this particular converter states a 5hp max? Or could it be used to power my 7.5hp motor?
 
Some folks use a 3X figure especially if the motor is one that starts under load (pump full of water, lathe with no clutch, compressor etc.). Barring that situation any good 15hp rotary should start a 7.5.
 
I'm attempting to power a horizontal mill.

I can just tread water with regards to electricity, electronics, so just being cautious after seeing the 5hp max warning.
 
Unfortunately you're not going to get an answer. There are all kinds of loads and it's going to depend on your load. I have a 30hp American Rotary and run all kinds of stuff off it at the same time. The newest Brother mill I have is a nice little load 99% of the time but when the spindle ramps it goes up to about 120 amps for a fraction of a second. At times I get errors on a few other machines due to this. With a 7.5hp manual mill I wouldn't hesitate to buy a 15hp American Rotary RPC based on my experience with mine. I have no idea for brands of RPC.
 
I have a question about phase converters I believe you guys can help me with.

I have a 7.5hp motor I need to power. I found a 15hp rotophase, but the trash says 5hp max motor. I've been of the understanding that a converter twice the size of the motor to be powered is all I would need.

Is there a reason this particular converter states a 5hp max? Or could it be used to power my 7.5hp motor?
You have to be smarter than the machine.
If this 15hp RPC says it will power a 5hp max
machine, that likely means it will, no matter how
difficult to start the load is. Anus protectus.
It will probably start a medium loaded 10hp motor
and a lightly loaded 15hp motor. But they are not
guaranteeing that. Just so you don't complain
to them about over rating their product, they are
likely under rating it. But the smart people with
experience know you have to take start up load
into consideration. It seems they are not, and
just saying 5hp max. All this comes from our
consumer expectation satisfaction society.
Ignorant people complaining with entitlement
expectations. Asking about a technical problem
here is a great way to cure the ignorant part and
also the expectation part. Best of luck with
your machine.

-Doozer
 
If you use an RPC too small for the load you are connecting to it with, maybe the start caps will kick in when you start your machine tool, because the applied load draws down the RPC too much. That is the only way I can see caps wearing out. Being an engineer, I ask "why" a lot, especially when someone tells me something that does not make sense. Usually they can not explain it any better. And then I know it is likely BS.

-D
Thank you Doozer, the application I am building is a hydraulic press that will use a Parker BB2HLUS44 hydraulic double acting cylinder 6" bore, 8" stroke, 3.5" rod, 3000 PSI rated.

Total cylinder displacement is 240 cu.in less rod displacement. The motor will be connected to a 2 stage hi/lo gear pump with adjustable pressure control for when pump shifts from low to high pressure. Tye control will be simple open, close and neutral where neutral bypasses fluid back to resivoir.

Motor is a B design which to my knowledge is medium start load designed for press/pump type loads.

I have both 5hp and 7.5hp motors that can be used in this application. Motor speeds are 3400rpm

My goal is to configure the best match possible to achieve 35-40k ton pressure and quick piston travel speeds in the 2"/sec range with max pressure in the last inch of travel.

This will be used to forge steel at forging temps

I have contacted the folks at KR West in Kaukauna, WI to get hydraulic details.

My research indicates a 16 GPM 2 stage pump should get me in that piston speed ballpark. And the 5hp may be enough, i am thinking the 7.5hp would be ideal.

I think the start-up load in this application is low and should bot be a proplem on my ADX 10 RPC.

Thank you for your response and to all the others that have weighed in.

Have a great day and weekend.

Rick
 
@johansen why do believe that long term overrated motor starts makes no sense?
the only capacitors that would be damaged would be the start capacitors, if you try to start a motor that is so large, the start caps get pulled in long enough to get warm. this would be on the order of the caps being pulled in for 10 seconds. and not once, but every few minutes, for several hours...

abusing the crap out of it. i'm talking a motor that takes 20 seconds to get up to speed since the start caps typically let go around 2/3rds nominal speed, or 160-180 volts on the generated leg, or they use a current based relay which means only God knows when they de-energize.

Anyhow if you need more starting power or better voltage under load, get yourself a 24vac 2 pole contactor for 12$ such as the link below, and throw away the 24vac winding and replace it with 2 to 4 turns of 10 awg wire. run your 3 phase loads through that 2 turn coil.
use the relay to switch in additional motor run caps. some experimentation needed. I have 4 turns of wire and the contactor does Not pull in at 16 amps, but it does at a reasonable current to pull in a start capacitor to start a 5 hp motor.

 
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Thank you Johansen.

I will keep this in mind as I move forward with the build. I may need some additional assistance on the electronic modifications you laid out above.

Please let me know if your willing to guide a bit at that time.

Rick
 








 
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