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Good match of vfd and motor?

PT Doc

Cast Iron
Joined
Dec 27, 2011
Location
Denver
I'm in need of a 3 hp 1760 rpm TEFC 3 phase motor for a belt grinder that I will be building for metal work. I have 240 single phase available to me.

I found this vfd:

KBAC-29D 3HP VFD 230VAC 1PH INPUT BLACK - Electric Motor Wholesale

This ac drive is 240 single phase input and 240 three phase output with a 3 hp max, 9.0 amp in a nema 4 box that I need due to grinding debris.

I also found this motor locally:

Products: AC Motors: EM3611T: Baldor Electric Company, a leader in energy efficient electric motors, linear motors and adjustable speed drives industry

Motor is 8.4 amp, 240v, 3 phase.

Do these look like they would work well together? Do all motors play nicely with an appropriately sized vfd?

Thank you very much in advance for your help.
 
This combination would probably work just fine, but you might wish to consider a Teco VFD from Dealers Electric which would be quite a bit lower cost, but would need more care as to location to shield it from grinding dust intrusion. I have been very happy with a Teco JNEV-203-H1 ($235.00) on my 3 HP Bridgeport clone. Goood luck.
Monoblanco
 
before buying it you should call them and have them send you a personal letter stating it will work with that, or any other 8.4a motor since when you read past the headline it says it is only rated 6.7amp rms not 9.0 amps -- why would they give 2 different ratings? I would say buyer beware due to this important inconsistency.......
 
before buying it you should call them and have them send you a personal letter stating it will work with that, or any other 8.4a motor since when you read past the headline it says it is only rated 6.7amp rms not 9.0 amps -- why would they give 2 different ratings? I would say buyer beware due to this important inconsistency.......

Thanks for the heads up on the discrepancy.
 
This combination would probably work just fine, but you might wish to consider a Teco VFD from Dealers Electric which would be quite a bit lower cost, but would need more care as to location to shield it from grinding dust intrusion. I have been very happy with a Teco JNEV-203-H1 ($235.00) on my 3 HP Bridgeport clone. Goood luck.
Monoblanco


I have looked at Teco. They make a 240 single phase input that can handle 3hp but it has a digital display and was would prefer just buttons, switches and dials. The KN might not work based on an amp discrepancy that I will need to sort out. Thanks fort the help.
 
I looked into to 6 amp RMS vs 9 amp discrepancy.

In this manual on the KB Electronics, it states that the Max current is 20.5 amps, circuit breaker rating is 25amps and the RMS amps are 9.0.

http://www.kbelectronics.com/Variable_Speed_AC_Drives_Inverters/AC_Drives_NEMA_4X.htm

They have a digital version of this VFD with 1 phase input but this VFD is 6,7 RMS amps with single phase with 9.0 with 3 phase.

I'll have to call to sort this out. Hope all goes well since I just found a Baldor 3HP motor for $250. 1750 rpm, 3 phase, super efficiency so its inverter ready and 20:1 turn down ratio.

Again, thank you very much for all the help.
 
it sounds like they are saying it is 9.0amp rms continuous if 3ph input and 6.7amp rms continuous if 1 ph input; since u will be using 1ph input it sounds like it must be derated to 6.7 max so will not work with ur motor. and dont let the added "rms" confuse the issue as they toss it in on one rating and not the other; all continuous ratings on 60 hz ac will be rms ratings so no difference whether they use the word or not.
 
it sounds like they are saying it is 9.0amp rms continuous if 3ph input and 6.7amp rms continuous if 1 ph input; since u will be using 1ph input it sounds like it must be derated to 6.7 max so will not work with ur motor. and dont let the added "rms" confuse the issue as they toss it in on one rating and not the other; all continuous ratings on 60 hz ac will be rms ratings so no difference whether they use the word or not.

Thanks.

I think they are truly 9.0 amps max. The KB manual for the #10001 states that and doesn't state a debating based on phase. The digital verison# 10003 is debated based on hp as are their other 3hp units. Weird that they have so many variations.

When I spoke its them 2 weeks ago, I thought I verified everything with tech support. But I will have to call again and revisit this. Emailing them and gettingj this in writing would be a good idea as was stated above.
 
Looks to me more like the reseller screwed up in their website, probably a cut-and-paste error. I think when they copied the 2HP drive data to make the 3HP page, they forgot to change the current data. The 2HP version is rated 6.7A, the 3HP is rated 9A. All of the mfrs data sheets show this, the only discrepancy exists in the on line retailer's web page.

As to the motor, that one is not specifically an inverter duty motor, but it may still be fine depending on what you want from it. If you are never going to run it below 1/4 speed for more than a few minutes, I wouldn't worry about it. If you are, then the fact that the cooling fan slows down with the motor will mean less cooling and you may end up damaging the motor over time. But then aging, how much do you run a belt sander? A few minutes at a time a few times a day? It will ake a lot of abuse before it shows any damage from that kind of duty cycle.
 
Looks to me more like the reseller screwed up in their website, probably a cut-and-paste error. I think when they copied the 2HP drive data to make the 3HP page, they forgot to change the current data. The 2HP version is rated 6.7A, the 3HP is rated 9A. All of the mfrs data sheets show this, the only discrepancy exists in the on line retailer's web page.

As to the motor, that one is not specifically an inverter duty motor, but it may still be fine depending on what you want from it. If you are never going to run it below 1/4 speed for more than a few minutes, I wouldn't worry about it. If you are, then the fact that the cooling fan slows down with the motor will mean less cooling and you may end up damaging the motor over time. But then aging, how much do you run a belt sander? A few minutes at a time a few times a day? It will ake a lot of abuse before it shows any damage from that kind of duty cycle.

It was explained to me by baldor that the super efficiency "e" motors were inverter ready with a 20:1 turn on capability. might need to verify again. Damn. Thought this was going to be easier but nothing ever is.

Thanks for the input.
 
Verified with KB Electronics: Kbac 29 (1p) is indeed 9.0 amp max. And good for 3hp.

Baldor em3611t is inverter ready. Baldor stated that all "e" motors are inverter ready.

Thanks for the help.
 








 
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