MEP003 voltage not stable

[Acableguy06]

First couple time running this machine has been running well. Put a 13k load on it for about 45 mins a week ago. Today I was running a more normal load 11-12k. When first started machine voltage was 128 on L1 and L3 60Hz then went to 120 each. Put load on, then the 50 amp breaker I have after the lugs popped and I looked and had 128v again, then went back to 120. Applied load again same thing a bit later, this time it hung at 128. Turned Voltage adjust down from about the 1-2o'clock position to about 10-11o'clock and it locked in there and ran or quite a while till I shut down.

Shut down for about 20 min, fired back up and was at 112v both legs. Let it run a few mins and no change. Bumped Voltage adjust knob back up to the 1-2o'clock and now been running 11k load for 30 mins and no change. Any thoughts?

Thanks

 

[Ray70]

3 Thoughts...

1) are you measuring voltage with the factory gage or are you using a DMM or known accurate digital gages?
The factory gages are not totally accurate, more of a ballpark reading.

2) If using a DMM or known good digital gage, first thought would be that your voltage adjust pot may be either dirty or otherwise unstable.
Typically when they start to get funky, the machine's vibration exaggerates the issue, so testing the resistance of the pot while rotating the knob and also while not moving the knob may or may not show an issue.

3) if your VR has a small hole in the front to access an internal pot for coarse voltage adjustment, I have also seen that pot go bad and cause voltage issues, but typically the swing is WAY more than what you are reporting.

 

[Guyfang]

Have you ever considered not overloading your gen set? Do you drive your car all day long at full speed?

 

[Acableguy06]

Have you ever considered not overloading your gen set? Do you drive your car all day long at full speed?

Well 11 k is about 46 amps of 52 rated

 

[Guyfang]

Well, 10 Kw is less then 11 KW. and 14KW for 45 min is even here in the land of sun and fun, over loading. But its yours. So do not wonder why it may stop some day.

 

[Acableguy06]

Well, 10 Kw is less then 11 KW. and 14KW for 45 min is even here in the land of sun and fun, over loading. But its yours. So do not wonder why it may stop some day.

Well I didn't run 14k it was 13 in my post, and I re checked what it was and 13k was not correct either, I never plugged in the other heater I had out so or was actually 12 was the max I ran. My apologies for the wrong number. I realize they say 10k but those numbers don't match the 52 amp rating on the plate. Was just running it close to that. So is the 52 amp rating incorrect?

 

[Ray70]

Any answers to post #2 as far as how you're reading the voltages?

 

[Acableguy06]

Any answers to post #2 as far as how you're reading the voltages?

DMM, killawatt meter, and the machine gauges all showed same thing.

 

[Ray70]

Ok, good info.
Also, disregard my earlier comment about the hole in the VR. I was thinking you had an 803 not 003.
On your machine the issue could still be a failing voltage adjust pot on the control panel and there are also a couple linear adjustable resistors on the VR that can get funny as well.
I'm not the electronics guy, so I can't tell you exactly what you should be seeing for resistance values etc. but I would start by measuring the resistance of your voltage adjust pot to see if it both changes smoothly as you adjust the knob and that it stays steady while left in 1 position.
You can easily rig up a couple leads to check it with your meter while running ( to duplicate vibration )
I'm pretty sure you can get some Detoxit or other contact cleaner inside the switch and work the switch around to try cleaning it to see if you get any improvement.
Your voltage movement is relatively small, but still not quite up to Par, so I don't think you have a major issue. Hopefully just a dirty pot.

 

[Acableguy06]

Ok, good info.
Also, disregard my earlier comment about the hole in the VR. I was thinking you had an 803 not 003.
On your machine the issue could still be a failing voltage adjust pot on the control panel and there are also a couple linear adjustable resistors on the VR that can get funny as well.
I'm not the electronics guy, so I can't tell you exactly what you should be seeing for resistance values etc. but I would start by measuring the resistance of your voltage adjust pot to see if it both changes smoothly as you adjust the knob and that it stays steady while left in 1 position.
You can easily rig up a couple leads to check it with your meter while running ( to duplicate vibration )
I'm pretty sure you can get some Detoxit or other contact cleaner inside the switch and work the switch around to try cleaning it to see if you get any improvement.
Your voltage movement is relatively small, but still not quite up to Par, so I don't think you have a major issue. Hopefully just a dirty pot.

I will check these things out and see if it does it any more. While I had the machine off between run times, I did cycle that VR pot knob back and fourth quite a bit to see if maybe was dirty. Haven't seen the issue again. Maybe it was that. Will try to get some contact cleaner in it and cycle it some more. And also check resistance values for smooth responses as well.

This VR pot does have a hole right above the main stem with a sloted stem in it as you described in your previous post. I assumed it was a coarse adjust pot.

Thank

 

[Acableguy06]

Have you ever considered not overloading your gen set? Do you drive your car all day long at full speed?

Guyfang, just to clear up. I fully respect your comment. I didn't feel I was overloading running 11-12k 46-50 amps. We all know 10k is a conservative number these are given. Was I running it running at max? Yes. That was the goal. Work it to max and see if there are any issues that pop up. I would rather buy parts now if they are not up to the task than when I need it. After all that's what testing and exercising is for. Make sure it's all working up to par for when we need them. I dont drive my truck at 100% all the time. However, there are times i need it to perform at 100%. I don't plan to run at 100% all the time. If it bumps 100% I want to know it can without crapping the bed.

 

[Guyfang]

Were good. I just hate to see it when people overload the sets. Testing is fine. But its like my car. I would not floor it all the time. Well, on the Autobahn, anyone driving slower then 120 KMH risks getting rear ended. These machines are older then lots of folks in the forum.