ALLIN1DC F1 Fuse Excessive Current

[tcortesi]

Hello,

We have an ALLIN1DC Controller on our lathe system. The problem we are having is that the F1 Fuse for the 120VAC is tripping (15Amp fuse). When I went about troubleshooting this, it seemed like something was shorting it out. After removing all the hot and neutral 120VAC connections from the terminal block, and testing them one at a time. The only one giving the problem was the wire #110H-111BLK, which goes to the CAPBRD LOW. So, with all the wires connected back, and this wire (#111) disconnected our machine boots up, but as soon as I add this wire back to the circuit the F1 Fuse will blow. Now to rule out what part of that circuit was giving the issue, we replaced the E-Stop Contactor/Snubber, and the CAPBRD LOW. After doing so, the F1 Fuse was still tripping. We even ruled out that it is the DC side that goes to the VM+ & VM- connections, since we had the E-Stop pressed cutting off that side of the circuit. I checked the problem wire for damage and could not find anything wrong with it, no obvious signs of shorting to ground.

After all this, we tried upsizing the fuse from 15amps to 20amps. And this surprisingly allowed the machine to boot up correctly as the fuse didn't trip this time. It seems that part of the circuit is pulling slightly more current than it should be but we do not feel comfortable leaving the 20amp fuse in there since the 120VAC Disconnect is rated for 16amps.

Any ideas why that 120vac circuit is pulling more current?

-Tom

[eng199]

Are you using slow blow fuses? The inrush during capacitor charging can blow fast fuses that would otherwise be adequately rated.

[tcortesi]

Yeah they are slow blow/time-delay fuses. We replaced them with the same one that was working previously, Littelfuse: FLM015. 15Amp, 250VAC or less rating.

[eng199]

Is there any bare metal on the bottom of the capacitor? It may need to be insulated. Due to part supply problems, some stud mount capacitors were sourced, then the stud was cut off. If the capacitor is mounted vertically and the system has no transformer, the stud could cause a short. This seems unlikely (because your short is not continuous), but may be possible if arcing is involved.

[tcortesi]

Is there any bare metal on the bottom of the capacitor? It may need to be insulated. Due to part supply problems, some stud mount capacitors were sourced, then the stud was cut off. If the capacitor is mounted vertically and the system has no transformer, the stud could cause a short. This seems unlikely (because your short is not continuous), but may be possible if arcing is involved.

It looks like the insulator does not wrap all the way around the bottom. So there is bare metal exposed on bottom of capacitor. There is no transformer going to it and it is mounted vertically (so parallel to the panel and CNC board).

I see what you mean though and I can give that a test tomorrow where I take out the CAPBRD and remove the mounting hardware, to rule out the arcing. Or I can put some liquid electrical tape on bottom to insulate it.

But like you said I would expect it to short out the 20Amps if it was arcing and I see no signs of arcing given my many tests. There is also about an inch air gap between the bottom of Capacitor and mounting screw to panel.

[tcortesi]

I went to check for arcing when turning on the 120VAC at the Capacitor and it didn't trip the fuse this time (15 Amp fuse). I am not sure why that is. Measured voltage the other day at 118VAC and today at 120VAC so not a huge difference. At first I thought it was because we had the 20 Amp fuse in there the other day and it allowed the capacitor to charge up and not need to pull as much at start up. But it has been off of like 1.5 days so I doubt there was still a charge on there.

This is the first time this as happened, I even turned it off and on again to see if it would repeat, and it turned on again no problem.

[lavrgs]

Guess what happened when I turned my machine on after replacing the cap n' board...? I don't have replacement fuses and my pal amazon is three days out. Maybe someone at the factory should in clude a note or put a piece of tape over it or include new fuses...