Retrofitting with Gecko G540 and VFD

[RandEE]

I am retrofitting an old EMCO mill with help from this forum. Without RCREDD I would be really lost, but I think I managed to screw something up even with his expert capabilities...

Right now I just want to set up the VFD, I haven't even connected the stepper motors.

The VFD is pretty simple, it's a KBVF-14 btw.
manual: http://www.kbelectronics.com/manuals/kbvf_2g_manual.pdf

It has spindle motor connections going to the U V & W of the spindle motor.
It has a LINE input for 120V operations, which is connected to the main power from the mail unit switch.
It has a POT input which I intend to use the gecko.

Without the POT input connected, I checked voltage between P1 of VFD POT Side and ground and got like 158v.
I thought my problem was the VFD now, I think I have an electrical problem.

I am just getting started on this, so not much is connected. The main 120V AC is spliced with 1 set going to the 48V PS and the other going to the VFD. The 48V PS just goes to the Gecko G540.

I know I am probably not explaining myself, so please ask questions.

Also, thanks for any assistance.

Randy

[Al_The_Man]

One thing to remember this is a Mains AC fed non-isolated drive.
If measuring anything on the pot terminals restrict yourself to P1, P2, P3, if you measure to ground, which is one side of the AC supply you may get strange readings, especially with a high impedance meter such as most current electronic meters.
If interfacing to something like mach you need a PWM to analog isolated convertor.
Al.

[RandEE]

Alright, I have done more testing and am still scratching my head...

I have disconnected and isolated the VFD from everything else. I made a new cord from the wall power 120v and connected it to the VFD and connected the spindle motor to the it. Once plugged in I am getting 60V between the ground wire (which isn't connected to anything) and the wall ground. When I check the voltage between the P1 (POT input 1 / LOW) and ground I get 160V. When I check the voltage between the P2 (POT input 2 / WIPER) and ground I get 160V and the spindle fires up full speed.

This is a used VFD, and is possible it's faulty. I just keep think I don't have something right.

Thanks for any help..
randy

[RandEE]

I am sure my meter is crap as well... just a cheap-o meter. So could you suggest a good way to test, making sure I have things right?

[Al_The_Man]

Well measuring any part of the drive to Earth ground, you could be looking at anything up to mains voltage.
The reading of the pot should be restricted to the three terminals P1, P2, P3, any interface to these three terminals such as a Mach PWM to analogue convertor should be an isolated unit and connect to the three P1 to P3 terminals only?
Al.

[RandEE]

Thanks AL, this is really causing me trouble. Just a hobby machine, but I finally purchased all the parts and would love to get it running.

Okay, so don't check to earth ground.
I just check the ground wire which wasn't connected to the VFD to the wall ground and got 30V odd for me to understand. I always thought ground should remain nothing unless something bad happens.

I don't have anything connected to the POT input. I just want to check and make sure it s okay before I connect it to the Gecko unit.

What I failed to mention in my first post is that I connected it all and the VFD started smoking. Just a tiny bit, but don't know if I fried it or it was fried. It still seems to work if I apply voltage to the POT input. Also the Gecko seems to be working. I applied 5V to it's VFD input and depending upon the RPM the POT output on the Gecko would change 2000 RPM created a 3V output, so it should be working, but haven't figured out why it smoked. I figured I had something wired wrong. When I noticed the 160V between the chassis and the POT input I figured something was way off.

Any suggestions?

[RandEE]

So i reconnected everything except I left the VFD on a separate wall plug so it wasn't spliced into the main. Turned everything on and put my voltmeter on the P1 and P2 POT input of the VFD. With the VFD off and the spindle off according to MACH3 I get 0V on my volt meter. When I turn the Spindle on I get 4.9V when I change the RPM smaller I get 3V. It seems to me like it's working as it should so I turn off the spindle in Mach3, my Voltage returns to 0v. I then plug in the VFD and the spindle takes off while the meter reads 0V.

[RandEE]

Thought maybe my crappy meter was connecting P1 and P2. So I just did my test without the meter same result.

Thanks!

[RandEE]

Finally got a POT and tested it with the same result. No matter what the POT is set to I get FULL speed. Somehow I think I am still getting voltage running through the ground and screwing me up. It's also possible that this VFD is just broke. Seems like everything else is okay.

Any suggestions are appreciated! Thanks, Randy

[RandEE]

Update...

I bought another VFD this time a KBVF-23D.

I have it wired with hot to L1 and neutral to L2. The connection reads 120V at the VFD board. The jumper is set to 120V operation. The spindle's U V W connections are all made and the ground is screwed into the heatsink. I am getting no LED light whatsoever. I checked the connections several times. I have not connected the POT connections and I have double checked the wiring from the breaker. All is correct according to the manual. I can't seem to find in the manual stating that L1 should be hot and L2 should be neutral. The manual states "Rated for 115 Volt AC line input with Jumper J1 set to the “115V” position . Jumper J1 is located on the upper PC board. Wire the Single-Phase AC line input to Terminals “L1” and “L2”."

Thanks for any help!!
Randy

[Al_The_Man]

Well according to the manual, you should have at Least the green power bus/logic supply LED, when you apply power to the unit.
The STatus LED will depend on various conditions.
It does not appear to matter on which is neutral as the input also allows for 2 hots.
Al.

[RandEE]

Thanks for the info. That is what I was thinking as well.

Looks like I have another bad VFD.