[Steoh]

I've finished everything on the conversion of my X2, and I checked A- on the X2 motor controller board for continuity with P1, P2, or P3 and I found it was with P3, which would make that the ground (0V). Does this sound correct? I'm ready to power up and test everything, but I don't want to fry my G540 by connecting the wires the wrong way around to terminals 7, 8, and 9 on the G540, so I thought I'd ask, as I'd hate to make a rookie mistake. Any help would be greatly appreciated.

Thanks,

Steph

[hoss2006]

better have a look at this tutorial
G540 VFD

[Steoh]

Thanks Hoss, but I actually followed that one, but it actually states that you need to establish the 0V terminal on the X2 control board, as it's not necessarily the same. It also states that the G540 can be fried if they are not connected correctly.

As I wrote, I measure P3 as having continuity with A- which would suggest they are both grounded, but I wanted to check my theory was sound?

Steph

[Al_The_Man]

From my understanding of what you are saying is that The motor control board P3 is common with armature -ve?
If this is normal, then that fact that the G540 is an isolated analogue command, it just means that the G540 pin 7 will also be at this common, but the rest of the G540 will be isolated.
It is unusual for a drive board not to have isolation between command and the motor circuit, but it normally should not matter.
I would suspect your armature DC has isolation from the AC in however?
Al.

[poopy_pants]

It's a simple test to verify. Pull the cover off to get access to the POT/Speed Dial on the Mill. There are 3 pins on the POT. One of the outside pins goes to Ground (that's your pin 7 on the G540), the other opposite outside pin goes to 5V from the motor controller (that's pin 9 on the G540), the middle is a variable voltage which is dependent on the POT position (that's your pin 8 on the G540). Use the link Hoss posted and depending on if you want to retain manual control of the motor, you may have to clip the middle pin on the POT or install a relay. Essentially, the G540 takes the 5V signal from the Motor Control Board and varies the voltage it sends back to what use to be the middle pin on the POT. If it sends 5V you're at full speed, 0V it's Off and you get the idea.

[Steoh]

It's a simple test to verify. Pull the cover off to get access to the POT/Speed Dial on the Mill. There are 3 pins on the POT. One of the outside pins goes to Ground (that's your pin 7 on the G540), the other opposite outside pin goes to 5V from the motor controller (that's pin 9 on the G540), the middle is a variable voltage which is dependent on the POT position (that's your pin 8 on the G540). Use the link Hoss posted and depending on if you want to retain manual control of the motor, you may have to clip the middle pin on the POT or install a relay. Essentially, the G540 takes the 5V signal from the Motor Control Board and varies the voltage it sends back to what use to be the middle pin on the POT. If it sends 5V you're at full speed, 0V it's Off and you get the idea.

Yes, I know how a potentiometer works, with the question being which wire is the ground. I removed the pot altogether, as why anybody would leave it in circuit is beside me? Again, I've seen the pminmo page before, but that doesn't answer my question, in fact Philip clearly states this needs to be checked on an individual basis, as he gives no guarantee his diagram is correct for all machines in this regard. Plus, it's 10V not 5V.

[Steoh]

From my understanding of what you are saying is that The motor control board P3 is common with armature -ve?
If this is normal, then that fact that the G540 is an isolated analogue command, it just means that the G540 pin 7 will also be at this common, but the rest of the G540 will be isolated.
It is unusual for a drive board not to have isolation between command and the motor circuit, but it normally should not matter.
I would suspect your armature DC has isolation from the AC in however?
Al.

Thanks Al, now that makes total sense, so the fact I have continuity between those 2 terminals (A- and P3) indicates they must share a common ground plane. It makes sense to me, but I just needed a sounding board before I flick the switch.

And yes, the DC better be isolated from the AC as otherwise there going to be a huge amount of ripple!.. not to mention magic smoke.

Cheers,
Steph