Suddenly I need som...
 

Suddenly I need some extra 3 phase. 10hp motor only $0.50/Lb. Did I get enough?  

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Gratewhitehuntr
(@gratewhitehuntr)
Joined: 2 years ago
Posts: 250
2018-10-29 07:45:38  

Spec sheet claims 300+Lbs for contemporary motor, we all know they've gotten lighter.

Sorry, they wouldn't let me use the supermarket scale ;P

 

Made in USA Reliance  10hp 1160rpm 3Ø 230v TEFC 256 frame  heavy son of my Mom!

I'm not EE, but it seems to me that RPCs with more poles would resist back-current better than those with less poles, ie. 6 pole vs 3 pole.

This is only a guess, either way this motor outweighs my current 5hp by 250Lbs, and the mass will aid slowing. (Yes I know it's not all in the rotor)

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With an old hand truck, 6/2-8/1 50A range cord, 3 pole fused safety disconnect , 50A FRN-N fuses,  some cheap generator plugs, and 75' of 12/4 SOOW.

I will build a larger RPC, it will be transportable, JUST LIKE the machine it runs <---hint!

 

My current Baldor 5hp is maginal-ish running the mill in heavy cuts, can't start with the Vari-Speed over 2500rpm.

It certainly is not up to the task of "pushing" my next shop tool!

Ohh it's gonna save me a lot of time, and increase safety! SAFETY---> I could use more!

 

Any guesses what the new tool is?

It draws 23A on 230v 3Ø

 

 

...... waiting for parts, so I am also being teased.

There you have it, the world according to John.


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MultimediaMan2K6
(@multimediaman2k6)
Joined: 12 months ago
Posts: 12
2018-10-29 08:07:20  

Probably a big lathe...

This motor, when used as a an RPC should be able to drive 5-7 horsepower reliably, if the input phases are reasonably balanced. The Rule of Thumb is roughly 2/3 of you caps should go to the Black Input (Phase A), with about 1/3 going to the Red (Phase C). Remember, you're essentially shoving "two phase", 180 degree input power into two legs of a 3 phase motor. No matter how you slice it, you're always going to be 60 degrees out-of-phase on those two legs, which is why we place an abundance of capacitors on one leg over the other - to try to get the voltages within range while the RPC is running - you might need to further tune the RPC Capacitors with the load motor also connected. A couple of RPC manufacturers have mentioned that 3450RPM motors are better for the idler...I have no idea if this is true, my 1750RPM Idler has worked fine for many years.

 


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Gratewhitehuntr
(@gratewhitehuntr)
Joined: 2 years ago
Posts: 250
2018-10-31 08:12:29  

Oh I wish it was a big lathe coming!

I've recently discovered a lack of max weight on "PODS" portable on demand storage.

My next big machine will likely be loaded in a POD at the seller's location, then delivered withing 3" of my shop door/slab!

Fuel costs,  GVWR, deck height,  and fatigue all considered, a POD looks reasonably priced.

 

 

MMan, your input on balancing is appreciated.

Many times has a salesman recommended the unit on their shelf as the best, but it should be taken with a grain of salt.

"Best" is subjective, and might involve best availability, best profit margin, best form-factor to ship easily... many bests.

It's important not to conflate "best for him" with "best for purpose".

 

I'll be driving a resistive load.

There you have it, the world according to John.


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Hector J Medina G
(@hector-j-medina-g)
Member of Trade
Joined: 2 years ago
Posts: 272
2018-10-31 09:30:03  

Please be so kind as to explain how you can put "resistive" and "motor" in the same phrase.

 

 

HM


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Gratewhitehuntr
(@gratewhitehuntr)
Joined: 2 years ago
Posts: 250
2018-10-31 14:00:53  

I do not see where the two words were used in the same phrase.

This is an induction motor, repurposed as a generator.

I will be applying it against drain to source resistance in on state, aka RDS(on), with max load being approx 9 kva, and 100% duty cycle load of 6 kva.

MmMan made a good evaluation @ 5-7hp (1hp=1kva) but it's NOT horsepower 😉

 

It is not a purely resistive load, there must naturally be capacitance and inductance in the system, since cords and conduit involved 😉

I've just got to ALMOST understanding electricity, my standard of "understanding" is rather rigorous, though I'm nowhere near EE status, and don't specialize in the NEC.

I know enough to put a cord on this, instead of wiring everything hard.

 

 

My first RPC was like climbing the rope in gym class, this feels like a ride on the down escalator...

Now, can anyone guess the LOAD?

 

 

edited for clarity, auto-misspell, and better info (hints)

 

There you have it, the world according to John.


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Gratewhitehuntr
(@gratewhitehuntr)
Joined: 2 years ago
Posts: 250
2018-12-30 15:02:42  

You may have heard me say, "I ONLY GET GOOD DEALS!" It's true, and you can follow this link to see the current retail, then check my screenshot!

Now you might also see why it's taking so long to build up tools, waiting for a deal means WAITING.

https://www.amazon.com/gp/product/B079YTQMDL

Actual price $440 after $100 "ESAB burn and earn" rebate!

+$90 for a 85ft SOOW 12/4 and $25 for plugs and receptacles.

MUCH better than the Chinese units I was comparing..... this cuts 1/2" steel at 100% duty cycle.

 

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There you have it, the world according to John.


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Gratewhitehuntr
(@gratewhitehuntr)
Joined: 2 years ago
Posts: 250
2018-12-30 17:05:04  

Curious as I am... could I cut my finger with this thing? Is it a lightsaber?

Am I gonna cut my whole arm off?

Sausage to the rescue!

Less than 1 second elapsed, less damage than I thought!

Most cuts are 1/8" depth and 1/4" width, a NASTY SCAR, but not fatal.

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There you have it, the world according to John.


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