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Assembling a 20hp Phase converter...Basic question on motors

CaryC

Aluminum
Joined
Sep 22, 2020
After a bit of research on this and other forums I have decided to "build" a 20hp phase converter using the American Rotary Panel-20. I am not building the converter from scratch due to time.

My question is will any 20hp 3-phase 60hz (In the USA) motor work? I know that 1,750rpm is preferred for noise, but what about other specs? :confused:

I am currently eyeing a used Baldor.

Thank you!
 
yep, looks just fine to use. most likely wye wound.

I think it is Wye wound, I need Delta. I am now looking at this motor which is supposed to be Delta or Wye...s-l1600 (1).jpg

It's made by U.S. motors. 1,200 RPM so I am hoping it would be quiet.
 
Will work just fine if you have the power to run it...Phil

Yah, really...

This PM forum has been FULL of issues where folk have gotten "optimistic" (and/or "greedy"?) about large idlers and had starting & CB trip problems.

I keep saying it. I'm not alone. Dave Kamp has published schematics. It is dirt simple to do.

A smaller primary and one (or more) "supplementary" idlers are waaay easier to start. And CAN end up at about the same cost for the same total power.

And even have better balance as to matching to the loads.

Because they don't always have to have all idlers online to support a given machine, any given period of time, anyway.

Sometimes, you only need the supplementary to START a load, can then drop it offline. Other times, a smaller one is all you need. And will waste less energy.

Considered two 10 HP?

A 10, a 7.5 and a 3 or 5 HP?

Two idlers can be HANDY as to flexible .... as well as easier to start.

THREE and there are more combinations, yet.

Four?

Well....... Only because I COULD!

:D
 
I keep saying it. I'm not alone. Dave Kamp has published schematics. It is dirt simple to do.

A smaller primary and one (or more) "supplementary" idlers are waaay easier to start. And CAN end up at about the same cost for the same total power.

And even have better balance as to matching to the loads.

Because they don't always have to have all idlers online to support a given machine, any given period of time, anyway.

Sometimes, you only need the supplementary to START a load, can then drop it offline. Other times, a smaller one is all you need. And will waste less energy.

I had a brief discussion with you in another section a while back about using multiple idlers. I had been meaning to pick your brain and others about it more. Dave Kamp has a lot of threads, and in a quick search I didn't see what I was looking for. If you don't mind posting a link or three I'd appreciate it.

I took a shot on a bid for a 20hp 1200rpm motor, and won. Should pick it up in a week or so. If it works it may be moot, but I was curious where are you connecting the supplementary idlers ? To the output connections toward load/ working machines ? Or tee-ing from the primary idler, with a switch or breaker ?

I've read where some have simply started another machine, but unloaded, for stability. But was unsure if that idle machine was actually working as a supplementary.

And when onlining the supplementaries, the lower amount of caps in control box is not a problem ?
 
I had a brief discussion with you in another section a while back about using multiple idlers. I had been meaning to pick your brain and others about it more. Dave Kamp has a lot of threads, and in a quick search I didn't see what I was looking for. If you don't mind posting a link or three I'd appreciate it.
LOL! Dave posted a "neat enough" schematic, but it was actually a bit of a joke on those trying to make a simple thing complicated.

You don't really need it, because...

...I was curious where are you connecting the supplementary idlers ? To the output connections toward load/ working machines ? Or tee-ing from the primary idler, with a switch or breaker ?

I've read where some have simply started another machine, but unloaded, for stability. But was unsure if that idle machine was actually working as a supplementary.

.. well.. that's the "joke" part as to not making a problem out of a solution!

As far as the electrons that are being pushed give a damn?

Those situations are all the same thing!

:D

The schematic showed an RPC's output.. with a supplementary idler (AKA motor).. connected to it.

With a contactor!

Full stop!

Same as if it WAS a "load motor"!

:)
And when onlining the supplementaries, the lower amount of caps in control box is not a problem ?

Actually it is the best part of the SOLUTION!

Not a "problem" at all!

What you do is put the "right amount" of run/balance capacitance on the IDLER side of each "activate me" contactor for THAT idler, as if it were to be the ONLY idler.. because NOW it CAN be.. and often WILL be!

NO run/balance caps, are left inside the "starter/controller" box at all.

Only the start cap(s) and either of: the manual momentary, ELSE timer, ELSE potential relay.

In my case, that's the start cap Jim Gorman (Phase-Craft) calculated for the original 4-pole 17XX RPM Brazilian-built Weg 10 HP bought brand new on promo with free shipping for somewhere around $387.... IIRC.

The run/balance caps he used get PHYSICALLY moved into a Zorro-sourced Weigmann ready-made NEMA rated steel enclosure on the 10 HP motor as an enhanced pecker-head.

I use DEEP! 6" (6 1/4" exterior) or 8" (8 1/4" exterior) boxes in various sizes because space to work stuff easily is cheaper than swearing and skinned knuckles. They have plenty of room for the caps AND the contactor AND protective device for that particular idler. They are "good enough" grey-painted steel NEMA boxes and much less expensive than Hoffman.

I have all manner of drills, hole-saws, nibblers, and annular cutters, do not WANT to go "Rons bat-f**k" cutting steel discs, Tig-ing them into knockout holes, bondoing, grinding, sanding the ugliness out, priming and painting and Blue-Coral waxing...... to make a used box cost five times as much as a brand new box "just because I know HOW!"

Good way to go hungry off running out of time to electrocute yerself a Young's of Grimsby fish & chips supper!

:D

Just add the "NK" (No Knockout) suffix when you order the silly box from Zorro online, and for small money, it shows-up on the front porch 2 days later with NO holes at all!

You need one hole for sure, more if it makes sense. Put those where they DO make sense and DONE. The paint is good enough as-had. Paint it p**y-pink if you dare and care to.

Now.. until you "bus" the contactors together?

You actually have "n" (four, in my case) fully-capable stand-alone idlers WITH the proper run/balance caps for their HP.

Just missing a starter & control.

Which we will "share" at the input side off the loadcenter.

Big enough wire and breaker to run the whole tribe when ALL are online. Even if that is not meant to be a "regular event".

"Code" sez each idler motor should then have a fuse or breaker rated to protect that lesser amperage. There's space in the big Weigmann box for bolting-in a "unit mount" SQ-D QO breaker. Or a trio of cartridge fuses. There's another option if you are up for some sheet metal or wire cage work.

As I need to do anyway, given the output hits a transfer switch (10 HP Phase-Perfect the other option), then a 27 KVA shared Delta-Wye transformer so I can re-derive a usable Neutral, and only THEN a 32-slot Square-D 3-Phase load center.

32 slots don't go all that far when a 3-pole breaker eats three at a go and you want a bit of unused space to group stuff for ease of remembering what is what.

NB: The "motor starter" function to NOT auto-restart after a power outage is inherent in the shared starter/controller box and the contactor actuation power sourced off a shared 24 VAC control transformer. And I'm not fussed about "heaters" for $250 NOS Reliance Duty-Master idlers anyway.

The 24 VAC control voltage goes dark, it stays dark, so the idlers are all disconnected until a human restarts the rig, manually.

Sooo... "in use" I always kick the 10 HP up onto the "step" first.

The Phase-Craft starter/control was built for it.
It is my heaviest starting load.
It is the largest, hence most-capable of starting the OTHER idlers, to wit:

3 HP, 5/7.5 HP, 5/7.5 HP. And the 10 HP itself, of course.

As the run/balance caps are ON the motor-side of the contactor at each idler, I can drop ANY of them offline, the initial 10 HP included, "start" cap no longer involved anyway, just the control transformer.

The combo of 4 idlers can be mapped to the start/stop control and just FOUR toggle switches, readable in "Octal" notation as if on an old Varian Data 520i, General Automation SPC 12, etc.

Same number of "states" "OFF" or zero included.

Just not in "binary". Even so, each "state" has a unique code and I can do Octal --> Hex in my sleep.

Annnd ....there are a couple of duplicates or near-as-dammit... a feature, not a bug .. because the HP is the same.. but the run/balance cap summation differs a tad.

Do the "truth table" and sub-in the "summed" HP as if building a threading chart:

....back shortly.. have to go find the chart in a "postable on PM" graphic format.

Meanwhile, two idlers is very useful, if only because vexatious starting issues are minimized. LOAD as well as idler itself.

Ex: NONE of my loads have clutches. ALL are run at light loads. So I need a boost for starting, but much less once up and running.

Three idlers usually makes more sense than four if you are making chips.

Chips are not my main goal, here. BTDTGTTS.

I'd rather make tests and do experiments in me old age. If the "many balance point" RPC or Phase-Perfect isn't close enough to Utility-Mains perfection? The MEP-803A IS.

Lemme go scout "which" hard drive and find that fool chart..

I try to NOT do "photos".

It tends to fry some people's tiny minds when they read too slowly to FIND the ones I have posted!

:D
 
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What you do is put the "right amount" of run/balance capacitance on the IDLER side of each "activate me" contactor for THAT idler, as if it were to be the ONLY idler.. because NOW it CAN be.. and often WILL be!

NO run/balance caps, are left inside the "starter/controller" box at all.

Only the start cap(s) and either of: the manual momentary, ELSE timer, ELSE potential relay.

Preface: My basic electric skills are decent/ok. I can do hook ups, change motor voltages, install service panels etc. And I know what volts and amps mean, and run checks. Figuring what or how much capacitors, and their actual function is a bit above what I understand, as well some of the other stuff.

Another preface: I have projects. . . My projects have projects :D. If I absolutely take nothing else on, I could probably work 2 or 3 years straight. Due to this, I would probably buy completed control boxes, vs building them from scratch.

If I am following you correctly, you have built your own control boxes for each idler motor, including supplementary. Even the supplementary need run/balance caps. Plus a trigger/switch or a way to start/stop or otherwise break connection.

If correct, I could use a vendor bought control box for each supplementary ?

And if that is correct, is the input to the supplementary simply L1 and L2 from utility ? L1 and L2, coming from utility power, are fixxed in their wave or rotation, with L3 I believe being formed/altered at 90 degrees. As you and others have done this, I assume primary and supplemetary are both getting L3 to the same 90 degrees ? No sync scope needed, like in running generators in parallel ?

And is L3 from primary rpc directly powering or starting supplementary rpc ?

I know your feelings on pics. You may be able to run it out in your head, but I need some visual aids. :D

Basic pieces that need the dots connected:

45.jpg

Option 1, Primary and supplementary as separate entities, but outputs connected at 3 phase service panel:

46.jpg

Option 2, primary feeds supplementary input power, as well as service panel. Unknown if supplementary is using L3 from primary.

47.jpg

Edit: potentially need breaker or switch between each control box and the service panel. So as not to back feed a panel that is offline, while another is online.
 
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Edit: potentially need breaker or switch between each control box and the service panel. So as not to back feed a panel that is offline, while another is online.

You are making a simple thing complicated. Just erase all above and start here.

No idler is a power source, save for a skosh of residual CEMF if running, then depowered.

The "source" you are concerned about is that two of the "hot legs" are powered from the single phase feed and go all the way and everywhere to any and all connected idler(s) and to any and all connected load(s). The electrons and "holes" don't care which end is which, the whole shebang is "hot".

The hard part for MOST folks to get ther mental "arms around" is that there is no such thing as an "input" side and an "output" side to an idler. People go mildly NUTS kidding themseves in trying to draw it and think of it as if there WAS a "side" or "flow" to it so as to force it into an inappropriate habitual perception.

Functionally, an attached/detached idler is no more "directional" than a meter's clipleads. They are either attached or not attached. RPC's DO reflect their kinkey-f**kery as to phasing back UP the single-phase feed as harmonic distortion, BTW.

The "solution" is that ALL idlers, the "pilot" or original included, are connected only by a contactor that interrupts all three legs. Same as all loads are.

Binary ON the bus or OFF the bus altogether, no "tri-state" required,

Meaning that EITHER the former primary and ONLY contactor in the still, yet, again ONLY "control" is now relocated onto the motor. Physically, not just "logically".

Or my case, simply abandoned in-place. Partly for a long-standing aversion to non-sealed contactors, and partly so I can reverse all this if/as/when it is ever downgraded back to a one-idler system.

As it MAY be.. If/as/when I can implement the Steelman-Haas conversion to even two, if not all three, of my largest load-motors.

I say again, NO load, NO idler has any connection to what has become the "bus" not 100% interrupable by its controlling contactor.

The "bus" within the load center for the CBs serving the loads is functionally the same AS "the" bus. Consider it always "hot" IOW - the upstream single-phase feed disconnect the "real" or "master" disconnect with the highest level of "trust'.

But nothing as attached TO said bus is not fully severable.

As to finding the drawing? Patience.

I had to go purchase a new Logitech thumb-ball for an older laptop that had been robbed. Couldn't even operate the Xfe file browser!

:(

The only thing I detest more than mice are damned-fool touchpads!..

Or small keyboards with poor tactile feel, my laptops always being operated from full-sized ones, plugged-in.

XXL glove size. I Just Faithfully Deal With That.
 
In my previous post pics, what I had labeled utility, I was just simplifying for single phase service. I have a single phase service panel in the shop, with a 40 or 50 amp breaker for my current rpc. I adjusted the pic in this post to reflect that a bit.

What I have labeled service panel is a 3 phase load center/ circuit breaker box.

Understanding that electrons don't care which direction they go, plus the idea of simplifying. Maybe this is more in line with what you mean:

48.jpg

With a contactor on each rpc control box. Not sure if the start button and its related components would do the trick, but my current start button needs to be pushed again if input voltage is lost. With power restored, machines don't automatic come to life. :D

Is there a purpose to installing the panels directly on the motor ? Save material, vs running more wire etc ?
 
In my previous post pics, what I had labeled utility, I was just simplifying for single phase service. I have a single phase service panel in the shop, with a 40 or 50 amp breaker for my current rpc. I adjusted the pic in this post to reflect that a bit.

What I have labeled service panel is a 3 phase load center/ circuit breaker box.

Understanding that electrons don't care which direction they go, plus the idea of simplifying. Maybe this is more in line with what you mean:

View attachment 310859

With a contactor on each rpc control box. Not sure if the start button and its related components would do the trick, but my current start button needs to be pushed again if input voltage is lost. With power restored, machines don't automatic come to life. :D

Is there a purpose to installing the panels directly on the motor ? Save material, vs running more wire etc ?

You aren't "showing" anything with a functional block diagram.

We need to look at a (hybrid) schematic instead. But so long as I am posting on PM, I ain't looking for my old drawings!

:)

What is on the idler is just a Weigmann box to hold contactor, caps, and protective device for the IDLER's nameplate, not the summed system. I think it actually needed LESS "large" (power) wire, and the control wire is dirt cheap?

It started "modular" by accident when I was long-wiring in the "borrowed" motor of a not-yet-restored mill that already had the Reeves belt off of it - so as to supplement the initial idler.

A collection of intentionally "modular" units mounted on El Cheapo "furniture" dollies at about 8 bucks apiece on sale from the local horror-fright seemed better.

At the time.

NOW the fool dollies are sagging, decaying, and the caster wheels gone sticky or rusting, so an upgrade has been in the works "for a while".

Plan is to migrate the whole shebang onto ONE re-purposed Northern drum rack dolly.

Once the aluminium shingles presently sitting on it find their way up to the roof, anyway. Shingles get off its twin, that one WILL carry Diesel fuel and the powered pumps and filters for "polishing" age-ing fuel. Just not in drums. Rectangular Aluminium tanks rather, and US-made, even though from Northern Tool!

Third drum-rack dolly has been down by the shop/garage door being prepared to get my Kasto PHS off the dodgy wooden stringers and casters it has been limping along on top of. Keeping the belt straight has been a PITA, so that was overdue.

I couldn't REALLY buy, cut, and weld the steel and apply decent wheels as cheaply as these uber-flexible goods have been on sale .. $89 with free shipping, yet:

Drum Rack Dolly Item #56697

Naturally, the sale price must have been a close-out as they've gone "no longer available", but for once "I got mine!"

:D
 
The Phase-Craft starter/control was built for it.
It is my heaviest starting load.
It is the largest, hence most-capable of starting the OTHER idlers, to wit:

3 HP, 5/7.5 HP, 5/7.5 HP. And the 10 HP itself, of course.

A couple of side questions.

I'm curious what your idling amps are with each stage of the rpc fired up. Not starting amps, just the idling amps. The amps to incoming single phase L1 and L2.

As an example, my 7.5hp rpc idles at about 8.7 amps, on each incoming single phase leg, L1 and L2. I would presume if running another near identical 7.5hp, that the two idlers together would then drawl 17.4 amps or there abouts.

I suspect idle amps may vary not just on hp, but the physical mass of the motor. Any particular hp can be physically large and heavy, while another of the same hp may be smaller.

But I was curious if you have measured those amps per motor, and with them running combined to see amp drawl on the single phase lines.

My other question was you have two of your motors listed as 5/7.5 hp. Are they 2 speed motors ? Why 5/7.5 hp?
 
Once spinning and with no load, the mass/inertia of the motor doesn't matter - it's not accelerating or decelerating so there's no torque on it.

I believe more inertia helps slightly when supplying other loads as it generates in some parts of the cycle and motors in others.
 
A couple of side questions.

I'm curious what your idling amps are with each stage of the rpc fired up. Not starting amps, just the idling amps. The amps to incoming single phase L1 and L2.
Figure is "don't care" as I have no need to idle them for any significant time. Am either runing a machine or not, no need of "standby". To the extent I am "dynamic" that way, I run the Phase-Perfect instead.

I can operate some stuff, such as the shaper or the vertical head + traverse motor of the Quartet mill with only the 3 HP idler active. OR the Phase-Perfect.

Percentage waste losses "in general" for RPC idlers are greater for larger idlers when run unloaded.

Under load the minimum waste is when closely matched or even "seems like" overloaded. As-in a 5HP idler being able to supply a 7.5 HP load.

The "magic" being the load is running at much less than nameplate max, so to an extent it is its OWN "supplementary idler"..

As an example, my 7.5hp rpc idles at about 8.7 amps, on each incoming single phase leg, L1 and L2. I would presume if running another near identical 7.5hp, that the two idlers together would then drawl 17.4 amps or there abouts.
There are other discussion on PM about Power Factor, direct credibility of clamp-ammeters or NOT.... etc. Also single-phase Amp load vs 3-Phase Amp load

It has all been done to death and I can't change the physics, so I don't waste a lot of time on the minutiae.
I suspect idle amps may vary not just on hp, but the physical mass of the motor. Any particular hp can be physically large and heavy, while another of the same hp may be smaller.
Also discussed to death. See-also "windage" & fans "modern" high-efficiency motors and their starting loads making less-attractive idlers than older designs, how hard it can be to start ANY larger single-idler RPC, "etc, ad nauseum"
But I was curious if you have measured those amps per motor, and with them running combined to see amp drawl on the single phase lines.
I'm sure I will once it is all back together on the new platform. I'll be long-lining it more to get the space back than any worry about the noise, deaf as I am, #4 THHN-W and such, so I have scant math to do for the distance and conduit runs, just the protective devices.

Breakers I have lots of - the advantage of sticking with Square-D "QO" for two human generations-plus since Corps of Engineers blessed them, year Zero.. so we'll see what is safe and least-hassle vs the sort of redneck bandaid/monkey-patch I have had so far.

Obviously, it will depend on what idlers are selected and what load(s) are up.

As said, I'm not fussed about idle-state waste as I don't need to let it idle that many hours, and it is about as easily scaled to the load as can be.

The Phase-Perfect is right efficient on-standby, BTW, though not "perfect" when idle. Lotta mag fields and statcoulombs being wanked about.

The Iron & cap anemic DC drives even MORE efficient! ISTR the SSD Drives idle at 500 MW, "waste" ony 55 W (mostly thermally) at full-gallop, so have a heat-sink, but do not need fans as a VFD might demand.

My other question was you have two of your motors listed as 5/7.5 hp. Are they 2 speed motors ? Why 5/7.5 hp?

Weird windings. GX type "constant torque". The reason they were so cheap,"NOS".
The 5 HP is a VFD or P-P synthesized Sine wave rating, 7.5 HP "true" sine wave.

They are 7.5 in this use, but I'm not planning for them to remain part of the experimental RPC "array". Not long-term, anyway.

Constant-torque, they will serve better on two of the machine-tools that have variable-ratio mechanical drive already as well.

If Steelman-Haas works for me, the two largest loads are off the RPC, so they won't need replaced in it. If it works WELL, I may do all but the small load-motors. The RPC "array" will get downgraded back to three, then two idlers - the 10 HP + 3 HP, most likely.

Steelman-Hass works REALLY well, the modular nature lets me peddle all or most of the RPC, piecemeal, and fall back to the P-P alone for the small stuff.

There is usually a madness in my method. "Mad" as to the profligate SPEND on my entertainment, if not also the Engineering! Ta da.. I do NOT have TV or cable news nor any sort of media feed though! Deaf usually, easily bored, always, why would I?

:)

As said, I research, make tests, do experiments. That's my "fun part".

"Play" is what human minds do best and most often, after all!

Happy to let OTHER folk make more chips! Made plenty of them, but even at Union Scale, and adjusting for inflation, making chips was far and away the worst-paid job I ever had for the environment of it, so not a lot of "nostalgia" for it!

Besides.. have to keep the mind ACTIVE!

LAST thing I need is a reversion to infantilism, as-in Walla Walla Whining, whom ISTR is about 8 years YOUNGER than I am and already badly brain-borked.

Hard to fault him for long. DNA dice-roll. No one ASKS for those.
Still.... not on my dance-card, thanks!

Rather take up sky-diving buck-nekkid or s**king 12-bore c**k than suffer dementia.

Then again, how would one know?

And could you do anything about it even if you DID recognize it?

:(
 
Figure is "don't care" as I have no need to idle them for any significant time.


As said, I research, make tests, do experiments. That's my "fun part".

Those are numbers you want to know. Not just for idling numbers, but for diagnostics as well, if watching amps you'll know if you have wiring or motor issues, as any faults will most likely drawl more amps. Particularly with experimenting and running checks.

Aside from idling or problem checking, id be interested in such cases where a machine would use multiple motors. If let's say rpc is 7.5hp, but combined machine motors are drawling 9hp, would it be more efficient to use two 7.5hp idlers, or a single 15hp. Just an example, but you get the idea.

I see the advantage of multiple idlers in less start up amp drawl, over a single equivalent hp motor. Just curious efficiencies where required hp may be in the area of running multiple motors in this sort of system.
 
Those are numbers you want to know. Not just for idling numbers, but for diagnostics as well, if watching amps you'll know if you have wiring or motor issues, as any faults will most likely drawl more amps. Particularly with experimenting and running checks.

Aside from idling or problem checking, id be interested in such cases where a machine would use multiple motors. If let's say rpc is 7.5hp, but combined machine motors are drawling 9hp, would it be more efficient to use two 7.5hp idlers, or a single 15hp. Just an example, but you get the idea.

I see the advantage of multiple idlers in less start up amp drawl, over a single equivalent hp motor. Just curious efficiencies where required hp may be in the area of running multiple motors in this sort of system.

As said. I don't care because I cannot easily CHANGE the Laws of Physics.

"Diagnostics" are for Data Networks and International Gateway class telco switches. BTDTGTTS.

Reminiscing just a day or so ago with one of my former staff over AN/FCC-22 Lenkurt FDM analog Mux channel grouping options, US Forward Propagation Tropospheric Scatter vs UK's version FPTS:

..a few famous C&W high sites breaking long distance records for TS. Trinidad (Morne Bleu) to Guyana was often in the record books...

Old Iron power-up in me dotage?

Happy to retire to SIMPLE "wire and forget" stuff, now!
One idler or "many" it is still only an ignorant RPC, and "BFBI" I can like!

Tropospheric scatter - Wikipedia

Back Porch, IWCs, Phil-Tai-Oki ... In the rear-view mirror, thanks!

I did say "retired?"
 
My $.02 on your last block diagram - run the single phase into a 3 phase breaker box/distribution center/panel. Run any 3 phase connections, machines, RPC controls, out through the breakers. Keep track of the wild leg, obviously. You can also pick single phase 220V off the two utility legs from your 3 phase wiring. It's code compliant and simplifies the wiring considerably.

Build a primary RPC with the American Rotary startup controls. No need for startup controls on the second, just fire it up after the first has started. Not best practice to use a breaker as a switch, but it does work, albeit with reduced life. Saves a disconnect, too.
 








 
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