VFD for 3hp motor.

C

Clearprop

Joined
Feb 14, 2014
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I would like to know the best recommended VFD to run a 3hp 3ph motor from 1ph 240v

The KBAC29 only drives the 3hp motor up to only 2hp of it's potential off 1ph 240v which is unfortunate because it's such a nice, clean, easy, vfd setup.

The VFD setup will drive a 3hp 1720 rpm motor on a 14×40 engine lathe as well as another 3hp 1720 rpm motor on a belt grinder. The lathe has a SPIN OFF chuck, so it CAN'T/SHOULDN'T brake/stop fast or it'll spin off and throw a 50 pound steel chuck at me.

The gears all work on the lathe, so full power at less than full rpm isn't crucial as long as it's full power at 1720rpm and double 3640 rpm, but full power at less than full rpm on the belt grinder will make a difference (sensorless vectoring?)

Need to be able to DOUBLE the 1720 motor rpms (I bought 1720's for their 4 poles of torque vs weaker 2 poles in the 3640rpm motors)

I have a discontinued TECO Jnev 2hp on my mill which is alright.
I have read sketchy things about the TECO L510's. The N'3 are another $100 but are they much more dependable? ...

Thanks.
 
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KBAC29 - feed it three phase power from a rotary phase convertor

You can set ramp up and ramp down speeds and avoid hard stops
 
If the 29 only delivers 2 hp on 220 single phase, does the 27 only deliver 1.5? Or 1?
 
The KBAC 27 delivers 2hp on 220v.....1.5hp on 120v single phase. To get full potential of 3hp on KBAC 29 you need Phase Converter.
 
That will do the job of speed control fine. However, it is an open frame VFD and will not last long in a metal dust environment. On a lathe that isn't as big a deal as on a grinder. Mount it above and a few feet away from the lathe and you will be good. Another way is to mount the VFD on the wall with the top of a shoebox size plastic storage box under it. Snap the box on the lid and it is dust free. You can take the box off when running the lathe, and snap it back in place when not in use to keep metallic dust from settling in/on the unit.
 
For a non nema 4 vfd I'll put it in a sealed tool ox or ammo box with air filters. Not a problem.

For about $225, the Teco L510 seems like it might be worth the gamble compared to the chinese vfds or a $360 KBAC29 + $$$ phase converter.

The lathe has a small discontinued 3hp "American Rotary" a phase converter on it.. the place I bought it from said it was in running operation when disconected and moved for sale. ... well.. they lied, when I wired it up correctly I literally cooked the motor and almost started it on fire because the rest of the circuitry on the lathe was bad.... I have a new motor for it now. Maybe if that phase converter still works, then a KBAC 29 will work too, but I'd hate to fry a new KBAC29 too (because I don't know if this phase converter is working properly either.)

What particular, reasonable, and reliable phase converter is recommended to put behind the KBAC29?
 
What about a weg nema 4x. Like the model: CFW080100BDN4A1Z

Ive got one of these running my milling machine. Haven't had any issues with mine. It doesn't have a pot on it standard so you have to use the up and down arrows to adjust freq. Looks like it drives more amps than the kbac 29 (not sure if this is the determining factor for how much power you get out of it). Only thing I don't like about it is that it has a fan that blows through the heat sink when power is connected so it makes a little noise. I had it hardwired in without an on/off switch before I realized.

I do love the kbacs for their simplicity. I've got 3 of the kbacs and one of these wegs.
 
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