Motor Amp Draw Question

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bkaesvziank

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Feb 23, 2018
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So I'm starting to build a 2x72. I've searched around quite a bit and everyone says that 1.5hp is the max that you can run on a 110 outlet. I was looking at motors from automation direct and they have a 2hp 3600rpm single phase that has FL amps of 17amps. I was also looking at the possibility of getting a 3 phase motor with a vfd but that's where I get even more confused. They have a 2hp 1800rpm 3 phase that has FL amps @ 230v of 6.0 amps. Does that mean single phase would be ~12 amps? Either of these should work on a 20 amp 110v, correct? To be completely honest I don't know much about electricity so any help would be appreciated.
 
1.5hp is the max you will get running a 3 phase motor through a VFD that is compatible with 110VAC, such as the KBAC-27d. You can get a 2hp single phase motor that will run on a 110VAC outlet. FLA will be around 24 or 25 amps, so it should really be wired up for a 30 amp circuit, though it will likely run on a 20 amp breaker if you're not loading it down too much.

Personally, I'd try to wire up for 220VAC if you can. If not, go with 1.5hp on a 20 amp circuit.
I'd definitely go with a VFD either way. It's a bit more cash up front, but still worth it at double the price. You'll then need a 3 phase, 1.5hp motor, wired for 220V (the VFD simulates 220V, even though you'll input 110V to the VFD).
 
I'd love to have 220v wired up but that's just not in the cards right now. I've got too much going on to dig a trench to my garage and then wire everything in. It's definitely something I'm planning on doing in the future though. Thanks for the info
 
(The following is in rounded numbers)

The 220 VAC three phase motor has three legs. It draws 6 amps per leg. That equates to 18 amps total draw.
If it was a single phase 22oVAC motor, it would draw around 9 amps per leg ... 18 amps total draw.
If it was a 120VAC single phase motor it would draw 18 amps.

The benefit of one over the other is that you can use 14 gauge wire for the 220V three phase setup, 12 gauge wire for the 220V single phase setup, but would need 10 gauge for the 120V single phase setup. Also, while all three technically would run on a 20 amp breaker, the 120V unit might pop the breaker when hogging.

Obviously, the biggest plus goes to the three phase motor, which can be made variable speed.
 
Everyone thinks if they run 220v to anything it cost's you half as much to run. Not true. But it can be more efficient but it does allow you to run smaller wire, breakers, etc.
 
A 1 1/2hp motor is a 1.1KW load. At 120 volts, it will draw 18 amps, at 240 volts it will pull 9 amps. At 120 volts 3 phase it will pull 9.2 amps. At 230 volts 3 phase it will pull 5.2 amps. At 460 volts 3 phase it will pull 2.6 amps.

Doubling the voltage will quarter the power needed per horsepower. Three phase power improves the efficiency of the motor 166 percent.

If you use a VFD to generate a 3 phase output, you have to take into account the efficiency of the drive. Your 460 volt, three phase motor fully loaded will pull 2.6 amps from the drive ouptut, but the drive will pull 21 amps from your 120 volt wall outlet.

Power out can never exceed power in. It's the law. You'll be waaaay ahead if you can figure out how to get 240 volts to your shop.
 
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You'll be waaaay ahead if you can figure out how to get 240 volts to your shop.

No doubt poster is absolutely right! BUT you have to consider MOST folks out there are not full time makers running grinders 8 hours a day seven days a week. They are hobbyists making knives for them selves to use or Christmas gifts, gifts to friends, giving knives away to people who appreciate them from someone willing to take the time to hand make them knives.

So don't give up on what you have to make knives. Do the best with WHAT YOU HAVE!
 
LCoop said:
Do the best with WHAT YOU HAVE!
Click to expand...

That is a fact! Also, the "KBAC-24D, & 27D: Designed to accept 1-phase AC Line input only (Terminals
L1, L2). Rated for 208/230 Volt AC Line input with Jumper J1 set to the "230V" position (factory setting). Rated for 115 Volt AC Line input with Jumper J1 set to the "115V" position. See Figure 11."

That should allow you to run a 2hp motor just fine with 120vac input, but ONLY at loads of 1.5 hp. Then "IF" you ever do get 220 vac in shop you'll be set with a 2hp motor and no hardware to buy, just rewire and move J1 jumper.

Please somebody correct the above statement if it's not true.

Ken H>
 
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