My thread has gotten so long, @Phillipw, that I don’t think anybody read the long descriptive post I made about what is going on now. Yes, voltage is starting all the way down at 25v, and building VERY slowly. The first cut was steady at 87v from right after the arc. I’m leaning towards something glitching with plasma cutter number two…
Because after I went away from it for half an hour, I came back and it worked beautifully.
When you have some time and will be with the table and plasma cutter. Get a ohm/volt meter and your hand torch and give me a call.
George
302-690-6995
I meant voltage coming to the plasma should have been more specific. Any chance of input voltage drop? Was your compressor running during failed cuts? I try not to ask questions until I read in depth but I agree.
It could have kicked on during one of them, but would have been off by the next. The garage is on its own 100A sub panel, and the plasma has a dedicated 50A circuit on that panel, and the compressor a dedicated 20A. We have 200A coming in at the street, so, no matter what my wife was up to, I don’t think so…? This is starting to get dangerously close to me being out of my depth, though.
Do you have a amp probe? you could kick on compressor and fire the torch to make sure. What size wire do you have on the 50 amp circuit?
Voltage drop has to do with wire size and length run vs load. Will test fine without a load. But put 30 or 40 amps on circuit and it could be dropping your Voltage 5 ~ 10 percent.
I have a Harbor Freight multimeter, which has an amp setting, but I’m not sure if it’s sensitive enough to show a spike, if you’re talking about seeing how many amps my compressor draws on start-up.
The compressor is fuse protected at 20A at the motor, as well as having a 20A circuit breaker in the panel. I think the motor itself is rated at just under 17A, but it can’t pull more than 20A for very long before the fuse will pop; it blew one a month ago when I forgot to turn it off and it tried to kick on in the middle of the night when temps were in the single digits. Yesterday was a pretty nice day.
The plasma is on 6AWG THHN, and I just ran that circuit last month.
I know you’re just throwing out ideas, but I’m about 99% sure the compressor kicking on didn’t cause this, but, I’m not very knowledgeable about this stuff, so let me tell you why I think so, and you can tell me if I should dig further into it.
First, I’m fairly certain the compressor didn’t kick on during these cuts yesterday, BUT it did kick on towards the end of my 1/4” project the day before, and it didn’t cause any issues on the 1/4” which was running at 45A. I’m running the 14ga at 30A, so wouldn’t the compressor’s power consumption be less of a factor? Also, it never runs for more than a minute or two, and I was going pretty slow yesterday (5 minutes between cuts), so it could have effected one of the bad cuts, but not all 3…
I see. The plasma is on 6AWG and the run is something like 30’. The cutter is plugged directly into the outlet. The sub panel is on a huge wire; I didn’t run it, so I couldn’t tell you what it is, off the top of my head. Probably 2AWG…I’m certainly not an electrician.
The plasma, the compressor and the lights were the only things with the potential to draw power yesterday.
The question is how far is your shop from the 200 amp box in the house?
We know the amp draw. We need to know if your voltage is dropping during a hard load. Like the compressor and plasma at the same time. Pick a 120v plug that comes off that sub panel. Set your meter to AC voltage and record the voltage reading. Leave the meter in the recep and run the compressor and cut something on the plasma table at the same time. See if the meter voltage drops.
This will let you know if the problem is the incoming power to the sub panel.
Your problem has a common denominator. Two plasma cutters doing the same thing. I was never a fan of primeweld, but it is what it is.
Easy to do and worth ruling out.
Good point. So, what is the maximum voltage drop I should be seeing with a big load on the sub panel?
My fluorescent lights dim briefly when the compressor kicks on, but I’m only seeing 1.5volts difference on my meter at the outlet. It dips maybe 4 volts when it first kicks on, but only for a split second. Turning on my 20A 220 heater drops the voltage another 1.5 volts, for a total of 2.5% with roughly 30A worth of load. I don’t really have anything to cut with the plasma at the moment, but as soon as I do, I’ll see where the voltage is then…
What is your 120v receps voltage reading?
Also check your plasma cutter receps voltage. It should be around 220v~240v or so. Your primeweld manual say it has a 15% + or - rating.
Lets just say plasma cutter uses 40 amps
Compressor and heater use 30 amps
Misc things like lights etc 10 amps
This will quickly add up to 80amps if for some reason the were all on together.
You could be approaching 15% voltage drop.
When I probe the plasma outlet I read from 238 to 244 volts; it constantly cycles, like 244, 238, 239, 241, 244, 238, 240, 243, 238, etc. With the compressor on it does the same thing, but from 235 to 241 volts, so basically 3 volts less across the range. My test leads are barely long enough to reach the prongs in the outlet, so I could be the cause for the cycling.
The 110 receptacle measures 118.9 to 119.1 fairly steadily, and drops to about 117.5 with the compressor running.
This is probably not the problem but its worth checkin out. One more check!!
Check your 120v voltage from the small blade
of the recep to the ground prong. So 120v lead to ground. Is it the same reading as you got before?
Yeah, receptacle hot to ground same as to common, @Bigdaddy2166.
And I did run the plasma with the compressor going and still only had a 2-3 volt drop at my receptacles.
The good news is, this may have somehow been a fluke, because I just cut out most of a 2x4 sheet of aluminum flawlessly.
BUT, now I have a new problem.
My project was 47.36” and my usable X travel is 47.897” (limit switch to soft limit). My loaded program triggers an excess machine travel limits warning, and it wouldn’t perform any of the cuts along the X- edge of the work, even though I could manually jog the machine well past the edge of my material.
I know this has to just be something dumb. Can anybody tell me where to look, because I really need to cut this same program again tomorrow…
The consensus on the Facebook group seems to be that the Pro just can’t quite cut this wide of a file. It’s advertised at 48.25”, and my table travel with limit switches is 47.897”, but I’m being told that the actual cut limits are just less than my 47.36” file. Does anybody know what the actual cut limits are, or how to determine them? I would think my X travel less kerf would be possible, but I’m still more than half an inch less than that. I’m really confused. And frustrated. And sick of wasting expensive material.
that isn’t quite right i several times i cut a full 48-inch sheet. my machine willl travel well over 48 inches something like 48.25 sounds right i will double check it early in the morning and let you know. with that said i don’t have limit switches and i run the older which i think is better version of fire control. Have you tried to turn the limit switches off?
I’ve had that suggested too. I haven’t tried it, yet. I emailed Langmuir support to see what they have to say.
honestly it has to have something to do with the limit switches or that version of fire control the one i used doesn’t care how what distance you tell it to cut it will definitely slam into the hard stops. Don’t ask how i know it was a green horn mistake.
I’m sure it does, @Phillipw, but the messed up part is that I can manually jog past where it will let my program cut, so it’s adding a buffer zone inside of the limit switch activated travel limit, and I have no idea how to know how much that buffer is, aside from trial and error.
Bummer…
