Another VFD question

J. Hoffman

J. Hoffman

Joined
Jan 1, 2011
Messages
1,798
How do you know if your motor will be able to handle a KBAC 24 running at double speed? There is a jumper that will allow you to run either single speed or double speed. I noticed that my other grinder came set up with a 1750 RPM motor set on double speed. My new motor is a 3/4 HP 60 hz at 1750 RPM. This is going to be a disc grinder, and I'm thinking that maybe the 1750 is fast enough, but not sure. But if I set it up to run double speed, can I cause damage to the motor or drive? I couldn't find any info on what is required to run 2X.

Thanks in advance.
Jess Hoffman
 
I would look up the motor plate model number. At least for Baldor no all motors are inverter ready. You could call the manufacturer to verify this. Who is the motor manufacturer?
 
It's a Baldor motor. I hooked everything up, and it didn't work. The VFD flashes the warning lights for load overload. I shut it down right away. I may try to find another motor to see if it works. Also, this motor was hooked up to a drill press and was using a magnetic starter. Does this motor need a magnetic starter?
 
What is your line side, single or 3 phase? Is the motor 3 phase?
 
Here is a photo of the plate, I think you can see all the info. If I'm missing something, please let me know. Is the green ground wire that is connected to the ground screw on the VFD suppose to just be connected to the frame of the motor? Or does it connected to 6-5-4?

Here are the important things.

Spec: 35R06-86
Frame: 56 513M
HP: 3/4
Volts:230/460
Amps: 3.0/1.5
RPM: 1725
Cycle:60
PH:3
Class: A
Code: K
DES: B
 

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Hello; New guy been lurking for a while and finally signed up, anyway, On the KBAC drive there is a jumper for inverter ready or non inverter ready motors (one or the other) Plus lots of other jumpers, plus a few pots to adjust, check and double check

Also I dont think you want anything like a magnetic starter between the motor and drive, you want the motor connected directly to the drive.
 
Dont connect the ground to 6, 5 , 4. They just get tied together and taped off. There should be a screw in the wiring box to tie the ground to (green screw)
 
ANeat said:
Dont connect the ground to 6, 5 , 4. They just get tied together and taped off. There should be a screw in the wiring box to tie the ground to (green screw)
Click to expand...

Ok, I was correct. I didn't think they got connected.
 
Mooseyard said:
It's a Baldor motor. I hooked everything up, and it didn't work. The VFD flashes the warning lights for load overload. I shut it down right away. I may try to find another motor to see if it works. Also, this motor was hooked up to a drill press and was using a magnetic starter. Does this motor need a magnetic starter?
Click to expand...

A magnetic starter allows you to hook up remote kill switches for industrial of school shops.
You don't need it to use the motor


Mooseyard said:
How do you know if your motor will be able to handle a KBAC 24 running at double speed? There is a jumper that will allow you to run either single speed or double speed. I noticed that my other grinder came set up with a 1750 RPM motor set on double speed. My new motor is a 3/4 HP 60 hz at 1750 RPM. This is going to be a disc grinder, and I'm thinking that maybe the 1750 is fast enough, but not sure. But if I set it up to run double speed, can I cause damage to the motor or drive? I couldn't find any info on what is required to run 2X.
Click to expand...

I woudn't think that double speed would be needed on a disc.

I initially thought maybe you didn't have a 3 phas motor, but yes you do.

If it came from an industrial installation, they likely had higher voltage power.

Is you motor wired according to the "low voltage" diagram?

4-5-6 together
9-3
2-8 together and connected to one of the hot 220v inputs "line"
1-7

ground may be green and is connected to the case

where does you other "line" power input connect to?


Look it up on the Baldor website, they can have a better diagram there
I can't get it to match anything
http://www.reliance.com/cgi-bin/mtrquery.pl


ANeat said:
On the KBAC drive there is a jumper for inverter ready or non inverter ready motors (one or the other) Plus lots of other jumpers, plus a few pots to adjust, check and double check
Click to expand...
http://www.kbelectronics.com/manuals/kbac_manual.pdf
Which jumper are you referring to ?
 
12345678910 said:
A magnetic starter allows you to hook up remote kill switches for industrial of school shops.
You don't need it to use the motor




I woudn't think that double speed would be needed on a disc.

I initially thought maybe you didn't have a 3 phas motor, but yes you do.

If it came from an industrial installation, they likely had higher voltage power.

Is you motor wired according to the "low voltage" diagram?

4-5-6 together
9-3
2-8 together and connected to one of the hot 220v inputs "line"
1-7

ground may be green and is connected to the case

where does you other "line" power input connect to?


Look it up on the Baldor website, they can have a better diagram there
I can't get it to match anything
http://www.reliance.com/cgi-bin/mtrquery.pl



http://www.kbelectronics.com/manuals/kbac_manual.pdf
Which jumper are you referring to ?
Click to expand...

The jumper is J11 for "overload selection" on page 18 (the bottom of the page) or figure 28 on page 19.
6.10 I2
t OVERLOAD SELECTION (J11) – Jumper J11 is factory set to the “1” position for Inverter Duty
Rated Motors. For Non Inverter Duty Rated Motors and HVAC applications, set Jumper J11 to the “2”
position. See Figure 28, on page 19. Also see Section 12.7, on page 24
Click to expand...

Also you mention connecting 2-8 to one of the incoming hot lines? I would not do that. Not in a VFD anyway. I would guess that would burn something up or at the least start blowing fuses or kicking breakers
 
ANeat said:
The jumper is J11 for "overload selection" on page 18 (the bottom of the page) or figure 28 on page 19.


Also you mention connecting 2-8 to one of the incoming hot lines? I would not do that. Not in a VFD anyway. I would guess that would burn something up or at the least start blowing fuses or kicking breakers
Click to expand...

J11
You're right I missed that.



I'm looking at this wiring diagram on the motor.

A 3 phase motor will have 3 lines in.
It's possible that they mean

I wasn't very clear on that

9-3 together and connected to one of the three phase OUT 220v "line" from the VFD
2-8 together and connected to one of the three phase OUT 220v "line" from the VFD
1-7 together and connected to one of the three phase OUT 220v "line" from the VFD


How do you read it then ?
http://www.bladeforums.com/forums/attachment.php?attachmentid=369877&d=1376103582
 
Yep, Thats right, When we start saying "in" "out" and other stuff in reference to the drive/motor/voltage source/etc.... Its easy to get wires crossed LOL (literally in this case) especially when we start troubleshooting or assuming some things are "right" and trying to figure out why things dont work
 
Count's right about the wiring. Three hot legs in, wired to 9/3, 8/2, 7/1. If it spins reverse of what you want, switch any two of the three hot legs into the motor.
Is that how you had it hooked up, Moose?
 
Salem Straub said:
Count's right about the wiring. Three hot legs in, wired to 9/3, 8/2, 7/1. If it spins reverse of what you want, switch any two of the three hot legs into the motor.
Is that how you had it hooked up, Moose?
Click to expand...

I've got it hooked up that way, but it doesn't run at all. The VFD just flashes overload. I'm bringing it to a local motor shop tomorrow morning to have them test the motor. I've never seen the motor run, but was told that it worked fine. I've gone over the wiring several times and can't find anything mixed up, I'm hoping that a fresh set of professional eyes will be able to find the issue.
 
Moose you can check the motor yourself to some degree with an Ohm-meter. With the motor disconnected from the drive read the ohms (resistance) from each leg to leg, The 9/3 to 8/2, 9/3 to 7/1, 8/2 to 7/1. Each one of those should read pretty low, just a few ohms to perhaps 20 or 30 ohms. They should also be all equal or really close. Also check each leg to ground, that should be very high, in the meg ohms to open depending on how sensitive your meter is.

Thats not a 100% positive test (It could pass all the tests and still be bad) but if something checks bad doing this test it is certainly bad

Does the motor smell burnt? does it spin freely?
 
ANeat said:
Moose you can check the motor yourself to some degree with an Ohm-meter. With the motor disconnected from the drive read the ohms (resistance) from each leg to leg, The 9/3 to 8/2, 9/3 to 7/1, 8/2 to 7/1. Each one of those should read pretty low, just a few ohms to perhaps 20 or 30 ohms. They should also be all equal or really close. Also check each leg to ground, that should be very high, in the meg ohms to open depending on how sensitive your meter is.

Thats not a 100% positive test (It could pass all the tests and still be bad) but if something checks bad doing this test it is certainly bad

Does the motor smell burnt? does it spin freely?
Click to expand...

It does not spin completely freely. It has what feels like some rough spots as you spin it. My friend (who is not an electrcian) thought that it was a type of magnetic brake that is deactivated when power is supplied to it. I don't know anything about that stuff. The guys that I'm bring it to tomorrow will be able to test it, fix it if it's broken, or sell me a new one if it's junk. I'll let everyone know what I find out. I really appreciate the help from everyone.
 
As I kind of suspected the motor is junk. The motor has no "magnetic brake" like my friend suggested. I brought the motor to my local shop and they tested it for me. I knew there were issues when I saw that the smoke had been let out of it. I don't know much about motors, but I know that they need the smoke inside to work, and as soon as the smoke gets out they no longer work.:D Anyway, I found a very decent place to buy motors and VFDs so I will just need to by a new motor now. At least now I can get a C-Face so I can add KMG's table attachment in the future. Thanks for the help everyone.
 
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