Baldor grinder vfd wiring question

[S4cruiser]

This is my first foray into 3 phase machines and vfds...so this is probably super simple to most!

The grinder is currently wired to a an old Rockwell pushbutton switch mounted in the stand. I have my vfd mounted above center and don’t plan to use the stand switch and would prefer to use just the vfd and grinder switch.

Can I rip out all this wiring (pic below) and wire the grinder directly to the vfd (and then vfd to single phase cord)? I think the answer is ‘yes’.

Need to dress the stone too before use.

 

[930dreamer]

Wire directly to the motor and use the vfd. I'd keep everything inside there, the next owner might have three phase.

 

[S4cruiser]

Wire directly to the motor and use the vfd. I'd keep everything inside there, the next owner might have three phase.

10-4, thanks!

 

[MattT]

I have my vfd mounted above center and don’t plan to use the stand switch and would prefer to use just the vfd and grinder switch.

Wire the VFD output directly to the motor leads, like 930 said. If you want to use the grinder switch for control, wire it to the VFD control terminals and config it as a run command.

 

[matt_i]

That looks like a fantastic tool. I have the "right half" of that, 2" belt sander, excellent tool for detailing.

It looks like your VFD has its own on-off switch which is unique.

What does the little toggle switch on the grinder base do? Is that for a worklight?

 

[S4cruiser]

That looks like a fantastic tool. I have the "right half" of that, 2" belt sander, excellent tool for detailing.

It looks like your VFD has its own on-off switch which is unique.

What does the little toggle switch on the grinder base do? Is that for a worklight?

Thanks, yeah it seems like a really handy tool.

Here is the vfd I’m using - https://www.kb-controls.co/product.sc?productId=35&categoryId=7 Not the cheapest option but is in a NEMA 4x enclosure. I chose analog controls as it’s just a grinder and shouldn’t need much programming, just on/off and potentially speed.

That toggle on the grinder body is it’s on/off switch.

 

[matt_i]

That toggle on the grinder body is it’s on/off switch.

I would bypass that switch making it non functional. You can permanently damage the VFD if you suddenly remove the motor load and cause the VFD to have to internally sink the power its pushing out.

If you want to use it, you should wire it to the low voltage controls (inputs) of the VFD and setup a "2 wire" start stop circuit.

 

[S4cruiser]

I would bypass that switch making it non functional. You can permanently damage the VFD if you suddenly remove the motor load and cause the VFD to have to internally sink the power its pushing out.

If you want to use it, you should wire it to the low voltage controls (inputs) of the VFD and setup a "2 wire" start stop circuit.

That’s good to know, I wasn’t aware. I’ll plan to bypass it, thanks.

 

[S4cruiser]

Ok...this is now a troubleshooting thread

I’ve got everything wired up as I think it should, but when plugged in
I get an overload fault. This is with the vfd not in the ‘run’ position, just idle with power supplied to it.

The KBAC-27D can be wired for 230 or 115 volt with 115v maxing out at 1.5 horsepower and 5.5 amps. I have this wired to run on 115v. The baldor grinder is rated at 1.5 horse power with 4.2 full load amps.

I bypassed the switch on the grinder base. The vfd jumper is set to 115v. Vfd is set to 1.5hp motor and 60hz. The vfd current limit is set to 160% which is the vfd factory setting.

The grinder is wired for it’s ‘low voltage’ configuration (vs high voltage).

115 volt extension cord is wired at the plug; black to brass screw, white to silver screw and green to the ground screw. Black is L1 and white is L2 at the vfd.

I’m stumped and am hoping it’s something I’ve missed that is easily corrected.

Here is the vfd manual - https://motorsandcontrol.com/files/manuals/kb/9521.pdf

Some pics...

 

[MattT]

The way you've landed the motor wires to the switch in grinder base looks suspect. Unplug the drive and wait a few minutes for the caps to bleed down. Then disconnect the motor leads from the drive. Ohm the leads out two at a time. Black to white, white to red, then red to black. You're looking for consistent readings of a few ohms. If that checks out then ohm one of the leads to ground. That should read infinity.

 

[S4cruiser]

The way you've landed the motor wires to the switch in grinder base looks suspect. Unplug the drive and wait a few minutes for the caps to bleed down. Then disconnect the motor leads from the drive. Ohm the leads out two at a time. Black to white, white to red, then red to black. You're looking for consistent readings of a few ohms. If that checks out then ohm one of the leads to ground. That should read infinity.

Thanks - I will do this tomorrow.

Re: switch wires...the black/red/white wires (2 of each) from the switch as just bundled together. They aren’t connected to anything, they’re as isolated from the rest of the wiring as if it was totally removed. Motor wires 1&7 are connected to black, 2&8 to white, 3&9 to red then 4,5&6 bundled together.

 

[S4cruiser]

Alright...

Wired it up to 230v just to see if trying 115v was the issue, it was not. Still same overload fault.

Ohm’d each of the 3 motor wires to each of themselves like MattT suggested. Readings of 2.8 for each. Ohm’d motor wire to ground wire and got a reading of 0.L on my Milwaukee multi meter.

Does this mean my ground is bad? I need to do some learning with ohm readings.

 

[MattT]

Alright...

Wired it up to 230v just to see if trying 115v was the issue, it was not. Still same overload fault.

Ohm’d each of the 3 motor wires to each of themselves like MattT suggested. Readings of 2.8 for each. Ohm’d motor wire to ground wire and got a reading of 0.L on my Milwaukee multi meter.

Does this mean my ground is bad? I need to do some learning with ohm readings.

O.L is probably how that meter reports infinity. If it's the same as the meter reads without the leads touching anything you're good there.

Will try to take a look at the manual later and see if I can find any settings that might be causing it.

 

[S4cruiser]

O.L is probably how that meter reports infinity. If it's the same as the meter reads without the leads touching anything you're good there.

Will try to take a look at the manual later and see if I can find any settings that might be causing it.

Super thanks for the help! I plan to call kb on Monday if I can’t get it working.

 

[MattT]

Super thanks for the help! I plan to call kb on Monday if I can’t get it working.

You're welcome. I've took a look at the manual and I'm not seeing anything obvious. About all you can do is check motor size jumper is set correctly and that all the rest are in place in their factory default positions. Other than J3 which I'd move to manual restart.

 

[S4cruiser]

You're welcome. I've took a look at the manual and I'm not seeing anything obvious. About all you can do is check motor size jumper is set correctly and that all the rest are in place in their factory default positions. Other than J3 which I'd move to manual restart.

Well...chaulk this up to me being extremely overly cautious. Everything works as it should, with no changes to my wiring.

I called KBAC tech support (they are nice and helpful) and it seems the ‘red’ fault light I was seeing is actually orange even though the manual does not indicate an orange light. It does mention yellow, which is correct when in the ‘stopped’ position. Tech support guy called it orange, oh well. I was just cautious and didn’t switch to start with the fault I thought I was seeing...turns out when turning it to start, motor speeds up and light turns to flashing green which is normal/appropriate.

 

[MFolks]

Hmm a tricolor LED? Have seen that in a few machines,used a lot on model railroad signals on layouts.

 

[S4cruiser]

Hmm a tricolor LED? Have seen that in a few machines,used a lot on model railroad signals on layouts.

Yep and steady vs flashing too! It’s an analog interface vs lcd...should’ve been a bit more foolproof but not so much. I wouldn’t discount operator error on my part tho!

 

[karoc]

Dang that is the cats meow,belt grinder and vfd it don't get any better