What's new
What's new

American rotary ADX-60 high amperage on idle?

Be careful with that 200 amp residential supply. The electrical transformer more than likely isn’t up to the task of the power needed to keep everything happy. This is one of those ask me how i know moments. 37 kva transformer if nobody else is on it would be minimum.
 
In my area (con ed, NY) residential meters measure only watts (W-hrs...) which is real power but industrial meters typically measure VARs (volt-Amp reactive) or the sum of real and imaginary current. If you have the first type you can determine power draw by integrating over a time interval, noting the meter reading before and after. If the real power draw is that low you may want to make the interval fairly long, an hour or two. Be sure to note the time interval.
Yes that is what I had at my old shop, I had a 400 amp 3 phase service that was measured in KWh, (old analogue spinner type)

Thanks for the suggestion Jim.
I am going to kick on the RPC tomorrow (during low energy cost time) and run it for an hour or 2 to find out the total amount of wattage used.
👍

I decided to wire up my CNC machines so that I can run the computers on single phase just L1 and L2 ,+ Turn off the low voltage safety locks.
Which means that I should be able to load up programs, and do some general set up before needing the RPC Running.
 
In my experience 3 phase motors draw 1.73 times the usual .3 x full load amps when run on single phase at no load.


37 idle amps would be more like 20 amps three phase which would correspond to a 60 amp FLA motor or...a 20 to 25hp motor.


As such I don't think any of your run capacitors are connected.

Friend of mine called me asked why his RPC wouldn't start.

After some troubleshooting discovered the 10 gauge stranded wires were stripped and...inserted too far into the start contactor. As such the setscrew had pinched through the insulation. After a few years of sucessful operation the couple strands that had been making contact finally blew up, and it didn't startup.
 
Also for what it's worth a friend of mine runs a silica sand operation in Eastern Washington.

They have about a 40k usd monthly electric bill, and they run a power factor of about 0.9. pretty damn good if you ask me.

So we were looking at efficiency improvements and I ran the numbers and came to the conclusion that the reactive power that the utility charges.. amount to the lifecycle cost of the capacitors that would be needed to offset it plus the power lost in the capacitors. Like even if I can find a 75kva capacitor bank on eBay for 200$ and then pay an electrician 1200$ to hook it up.. it isn't guaranteed to
pay for itself in 5 years.

Your utility may be different...
 
Lots of good info here BT Fab!

Thank you for taking the time out of your day to help me with this. I'll check the printing on the caps when I am at the shop later to see what the ratings are on them.

After all this I feel a lot more comfortable running this machine.
Didn't want to rush into it, because I didn't want to be billed by my electric company for a idler drawing 5x what it was supposed to all day... And if there was something wrong with it I wanted it corrected ASAP. Not just the $7k RPC at stake but I have a lot invested into the 4 CNC machines that will be hooked up to it.
My old shop had 3 phase already so I didn't have to worry about a RPC.

I assume that if this were your machine you would feel comfortable running it at this point?
yep, it sounds fine, having a large 60hp will be good to run 2 machines, all depends on spindle HP/KW needed to run it. thankfully mine is only 7.5Kw spindle on my 20 and its been fine.
 
That is a good point, I have 200 amps available at this shop, and from my load calculations it should be enough for now. All the wires are more than sufficient.
But is possible to install power factor capacitors if I need to in the future?
I imagine that I would need to have the capacitor bank hooked up through a contractor controlled by an ammeter so that they turn off when there is sufficient power draw on T3?
Dispite my mediocre understanding of induction motors and reactive current I can design and build a circuit board of necessary.
with only 200A id be worried if ever turning on a large load IE a 20-30HP spindle while another is running and dropping out the voltage too low. Although you could do the cap bank but the motor should help smooth out the spikes because of the 2X load size which is usually the design. as when the voltage drops out, the current goes up alot and thats when electrical components start getting toasted as they are only regulated for X amount of watts through it at 230V but if it drops 30% you need more amps through the same part which creates heat and starts shorting things out internally.
 
The full load current of a typical 60hp motor at 240v is 150 amps.

As such your 37 amps idle current is not terrible, most of the idle no load amps have already been corrected with capacitors.

The adx-60 says the single phase amps are 78, when a 20hp 3 phase load is run... That's what matters. That's a power factor of 0.8, not bad at all.

If you are seeing an extra 20 amps or so under load, then check to see that all the run caps have current flowing, and call them to verify their claim of only 8 amps no load.. (seems unbelievably small for a 60hp motor, even corrected with capacitors)
 
Skipped. ADX60 appears to be a 40 HP idler motor. According to NEC table 430.250, full load amperage for a 40 horse, 240V motor is in the neighborhood of 104 amps. A 36 amp no-load current is realistic for a 40 horse motor. The only way you will get that lower is with power factor caps. If this is a residential service then I wouldn't bother since you won't be billed for what is mostly reactive power. Even if you do get billed for it, the cost of power factor caps on such a small scale will likely fail to amortize within any reasonable span of time.

When we install power factor caps in the industrial world, it usually takes the form of an Autovar unit or a static cap bank fed directly off of one or more 0.5~2 MVA indoor unit substations which step down 13,800 volts inside of a 2-hour rated transformer vault. A 200A single phase service might as well be a 9V battery by comparison in terms of utility billing. The places I'm talking about burn four digits a day in electricity and have utility-dictated power factor requirements of 0.90 or 0.95 in order to avoid additional fees. Factories, hospitals, data centers, high-rises, etc.

be-mv-unit-substations.jpg


If it ain't broke, don't fix it. No sense reinventing the wheel.
 
Last edited:
Be careful with that 200 amp residential supply. The electrical transformer more than likely isn’t up to the task of the power needed to keep everything happy. This is one of those ask me how i know moments. 37 kva transformer if nobody else is on it would be minimum.
Haha I thought ahead on that, when I wires the shop and turned in the load calcs to the power company I "loaded" the estimated requirements.. when they came out they swapped out my pole pig to a 50va.
However I did just realize today that each time I kick on the RPC the lights in my house and my next door neighbor's house dim for almost a second...
Oh well...
😅
 
The full load current of a typical 60hp motor at 240v is 150 amps.

As such your 37 amps idle current is not terrible, most of the idle no load amps have already been corrected with capacitors.

The adx-60 says the single phase amps are 78, when a 20hp 3 phase load is run... That's what matters. That's a power factor of 0.8, not bad at all.

If you are seeing an extra 20 amps or so under load, then check to see that all the run caps have current flowing, and call them to verify their claim of only 8 amps no load.. (seems unbelievably small for a 60hp motor, even corrected with capacitors)
Thank you Johansen,
Seems like my RPC is in line and the amperage claimed by American Rotary is (at least somewhat accurate) though it would have been nice to have no extra reactive current heating up wires, maxing out breakers and such.
 
with only 200A id be worried if ever turning on a large load IE a 20-30HP spindle while another is running and dropping out the voltage too low. Although you could do the cap bank but the motor should help smooth out the spikes because of the 2X load size which is usually the design. as when the voltage drops out, the current goes up alot and thats when electrical components start getting toasted as they are only regulated for X amount of watts through it at 230V but if it drops 30% you need more amps through the same part which creates heat and starts shorting things out internally.
yep, it sounds fine, having a large 60hp will be good to run 2 machines, all depends on spindle HP/KW needed to run it. thankfully mine is only 7.5Kw spindle on my 20 and its been fine.

I went around wired up and tested a few of my machines today and so far no problems, I do have a 41hp spindle in my Kitamura 3vx but it is ran on a vfd (so it doesn't start hard) and I don't intend to run it too hard or often here.. and probably Not when other machines are hogging power. All my other machines are in the 7.5 -15 hp range and it doesn't look like I will have any issues running them, today I set my 15hp chevalier up and had it hog out a chunk of scrap 6061 and ran my 10 hp American Pacemaker full tilt through a piece of bar stock at the same time, checked my clamp meter and multimeter. Amperage seemed acceptable and frequency from the RPC stayed very stable.
I think I will wire up volt meters next to the machines in the future so that I can keep an eye on it.. almost all my CNC machines have a high-low voltage safety shut-off. With a programmable threshold.. so I don't think I will have any issues with those.
Things seem to be coming together, can't wait to be making parts again :-)
 
Skipped. ADX60 appears to be a 40 HP idler motor. According to NEC table 430.250, full load amperage for a 40 horse, 240V motor is in the neighborhood of 104 amps. A 36 amp no-load current is realistic for a 40 horse motor. The only way you will get that lower is with power factor caps. If this is a residential service then I wouldn't bother since you won't be billed for what is mostly reactive power. Even if you do get billed for it, the cost of power factor caps on such a small scale will likely fail to amortize within any reasonable span of time.

When we install power factor caps in the industrial world, it usually takes the form of an Autovar unit or a static cap bank fed directly off of one or more 0.5~2 MVA indoor unit substations which step down 13,800 volts inside of a 2-hour rated transformer vault. A 200A single phase service might as well be a 9V battery by comparison in terms of utility billing. The places I'm talking about burn four digits a day in electricity and have utility-dictated power factor requirements of 0.90 or 0.95 in order to avoid additional fees. Factories, hospitals, data centers, high-rises, etc.

be-mv-unit-substations.jpg


If it ain't broke, don't fix it. No sense reinventing the wheel.
Good advice sparky! I am a habitual and incurable Tinkerer, I am always trying to make things better... But sometimes I need to leave well enough alone and move on.
I have about half of my machines moved in and wired up today and they run fine on the RPC, power doesn't seem to be an issue and I will put my time towards making parts :-)

I am fascinated by the industrial power world you work in though. I used to design and build networks for Cisco some of the places I worked in had absolutely huge machines.
like paper mills had huge paper corrugation machines. I remember that the VFDs that they used had so much background EMF. It didn't play nice with our servers and network equipment.
 
Also for what it's worth a friend of mine runs a silica sand operation in Eastern Washington.

They have about a 40k usd monthly electric bill, and they run a power factor of about 0.9. pretty damn good if you ask me.

So we were looking at efficiency improvements and I ran the numbers and came to the conclusion that the reactive power that the utility charges.. amount to the lifecycle cost of the capacitors that would be needed to offset it plus the power lost in the capacitors. Like even if I can find a 75kva capacitor bank on eBay for 200$ and then pay an electrician 1200$ to hook it up.. it isn't guaranteed to
pay for itself in 5 years.

Your utility may be different...
40K electrical cost seems out of this world but I've seen some industrial applications that I could imagine being somewhere in this range.

My utility isn't so bad on cost, I've decided to leave well enough alone and just run my machines :-)
My power company isn't charging for reactive power since I'm on residential and their rates aren't too bad (certainly could be worse).
 
I would point out that rotary converters do NOT draw the FLA current as if they were actual fully mechanically loaded motors of that size. Example: my 5 hp rotary converter draws around 200 watts at idle.
 
40K electrical cost seems out of this world but I've seen some industrial applications that I could imagine being somewhere in this range.

My utility isn't so bad on cost, I've decided to leave well enough alone and just run my machines :-)
My power company isn't charging for reactive power since I'm on residential and their rates aren't too bad (certainly could be worse).

if you can spend $7,000 on an rpc
you should spend it on a VFD
they actually design them now for your exact scenario

your CNC machines will like them MUCH better than an rpc
rpc's are fine for simple motors, but they dont play well with complicated computer controlled machines

an rpc is not a generating station, no matter how well you design it and tune it
it is still a poor boy fix

even when you take the time to avoid the generated leg for your controls
a vfd will also remove supply line problems that would otherwise be transferred straight thru to your machines computers
such as spikes and dips (lights dimming during start up, brightening at shut off) your computers in your machines will be living with that dirty power indefinitely.
also you will not have to modify your machines, factory wiring can be left alone and not void the warranty

if you have the money to buy new, then you have the money to buy VFD's
 
If you can use an RPC, and want better, do NOT get a pallet of VFDs for each machine to have one.

Get a Phase perfect, and never look back.

OK, you "CAN" just get a huge VFD, leave it set to mains frequency, and use that as the "poor boy's PhasePerfect".

If you want variable speed, sure, get a VFD.
 
if you can spend $7,000 on an rpc
you should spend it on a VFD
they actually design them now for your exact scenario

your CNC machines will like them MUCH better than an rpc
rpc's are fine for simple motors, but they dont play well with complicated computer controlled machines

an rpc is not a generating station, no matter how well you design it and tune it
it is still a poor boy fix

even when you take the time to avoid the generated leg for your controls
a vfd will also remove supply line problems that would otherwise be transferred straight thru to your machines computers
such as spikes and dips (lights dimming during start up, brightening at shut off) your computers in your machines will be living with that dirty power indefinitely.
also you will not have to modify your machines, factory wiring can be left alone and not void the warranty

if you have the money to buy new, then you have the money to buy VFD's
As far as I know VFDs do not like high starting currents and would not work well for running my CNC machines which will be turning on things such as coolant pumps, hydraulic pumps (under load), vacuum pumps etc. Those kind of things have very high amperage draw on startup and will cause any vfd I know of to error out. (Unless you are suggesting installing a vfd or soft start on every motor, I don't particularly like the idea of that as it would require something in the range of 30-35 VFDs in my shop...

Either way this RPC has been running great voltage is very stable between phases and has been running my CNC machines beautifuly so far. (I have a machine that will draw almost 85 amps continuously under full load and it hasn't had a single issue :-) though I haven't had that machine run at the same time as any of my other big machines, only manual lathes and mills.
 
If you can use an RPC, and want better, do NOT get a pallet of VFDs for each machine to have one.

Get a Phase perfect, and never look back.

OK, you "CAN" just get a huge VFD, leave it set to mains frequency, and use that as the "poor boy's PhasePerfect".

If you want variable speed, sure, get a VFD.
I have VFDs on several of my smaller machines and some of my CNC machines use them for the ATC spindles but I am still feeding most of those VFDs 3 phase power from my RPC. (I could get larger VFDs and de-rate them for single phase but this is working for now and isn't costing me Thou$ands.

I have never seen PhasePerfect, how does it handle large start up loads? I know that most VFDs can't handle a large motor turning on while they are already running and will error out.
That is why you can hook a vfd to a half dozen motors and spin them up to speed but you can't have a vfd running a single motor and just flip a breaker and connect a second one. It will overload the vfd and it will go into a fault.

Any downsides to PhasePerfect aside from the price?
The RPC is working great for me here RN and hasn't had any trouble. But but I might look at PhasePerfect in the future if I have to upsize / build another shop where I can't get 3 phase.
I imagine internally it is basically the same as a large vfd with a rectifier circuit, capacitor bank, dc bus and a stack of IGBT. With some simple electronics it would be easy to match voltage and frequency output with input. And with oversized components + less nanny circuitry it could easily handle heavy start-up loads I assume.
 








 
Back
Top