MEP 831 ran fine now Short Circuit / Overload turns it off.

[ECS]

I have a low hour MEP 831 with 30 hours, ran it 10 hours now the next day after cooling off the Short Circuit / Overload light turns on after starting it and running about 10 or 15 seconds and shuts down the generator.
This is even before activating the circuits.

It starts right up and then shuts right down with the red light indicating Short Circuit / Overload without any load.

What would be broken here?

 

[kloppk]

The inverter itself senses and determines if there is an Overload/Short Circuit OL/SC) situation. The K8 OL/SC fault relay is inside the inverter.
On the surface it might appear that your inverter has gone south.

 

[ECS]

Thanks,

So to fix it does the whole inverter need to be replaced (usually)? or would some wires need to be replaced?

 

[69birdman]

Do you leave the machine outdoors? I think they are quite susceptible to moisture & humidity. I live in Florida, hot & humid, mine was throwing the overheat fault minutes after starting. I opened up the fault indicator, no visible moisture, but I dried it out awhile with a hair dryer. Hasn't done it since, I keep it in the garage now and keep little moisture desicant packs in the control panel.

 

[dav5]

My 831A is in the bush and is also very susceptible to moisture even though it is in a ventilated enclosure. It shows a short circuit fault but doesn't shut down the engine. I run it closed for 10 minutes or so shut it off and restart it and the fault is so far always corrected.

 

[ECS]

Thanks !!

That was it !!

I dried it out and it ran fine. I guess it didn't like being in the Florida down pour overnight and the super high humidity.

 

[Ray70]

Interesting, so was it the Fault control panel that you dried out, or just the control box in general?
My 831 was running fine ( other than a governor controller issue that Kurt is generously assisting me with ) a couple days ago, but today it starts and 4 seconds later trips the overload, consistently.
It has never been rained on, but the weather here has been 90+* and close to 100% humidity for almost a week.
Suppose my first step should be to make sure the high humidity isn't causing the problem!

 

[kloppk]

Ray,
The inverters in the 831's are fussy about high humidity and will throw OL/SC faults due to it.
Will do a lengthy write up tomorrow on info I have about it and what looks like a promising solution.
Kurt

 

[Light in the Dark]

Does it involve putting 831s into smelting ovens to make lifetime supplies of fishing sinkers?

I could actually really benefit from having a smaller backup for nighttime runs (my 802 will consistently run just above 1kw overnights when all are sleeping) as I found out last night for our first outage in a LONG time... these little devil machines though are only redeemed through the items you have produced for them Kurt.

I was going to convert one of the older open frame Yanmar/Dewey units to a 240V head (actually already own the head)... someday.

 

[69birdman]

Interesting, so was it the Fault control panel that you dried out, or just the control box in general?
My 831 was running fine ( other than a governor controller issue that Kurt is generously assisting me with ) a couple days ago, but today it starts and 4 seconds later trips the overload, consistently.
It has never been rained on, but the weather here has been 90+* and close to 100% humidity for almost a week.
Suppose my first step should be to make sure the high humidity isn't causing the problem!

Ray
It was the fault indicator that I dried out. I unplugged the harness and removed the nuts and cover, propped a hair dryer up to it for 15-20 minutes. I'd read an old thread of false fault shutdowns , Guyfang had commented that moisture was common problem. Probably just having everything opened up , sitting in full sunlight, dried out the inverter.

 

[kloppk]

Ray,
The OL/SC moisture problem has to do with the main control board in the 831A's inverter.
The main board is covered with potentiometers that are adjusted when the inverter is tuned at the factory. TRC decided to NOT seal the potentiometers after the inverter was finished. The problem appears to be an issue of moisture getting into the pots and causing the board to "think" there is an OL/SC when there isn't. Numerous people have reported that they were able to get the problem to go away by running the gensets engine with the inverter disconnected for a while to use the engine heat and airflow to dry out the board. Only problem with that is the problem can reappear again due to another humid stretch.

I helped a customer whose 831 was plagued with OL/SC faults whenever it was humid. We discussed the problem and I let him know about the main board's moisture weakness with the pots. I had him pull the main board out of the inverter and bake out the moisture in the oven for a few hours at a low temperature. Once done he then sealed up all the pots with Conformal Coating such as MG Chemicals 419D brush on CC. Once dried he re-installed the main board and the invert worked as it should. Over about a 6-week period he subjected the 831 to rain and humid conditions as well as wetting the set's outside with a hose. Each time the set started and run without throwing any OL/SC faults. Since then, he hasn't reported any subsequent OL/SC faults.
Seems that drying the main board and coating the pots is the solution to the problem.

 

[Ray70]

Gotta say Kurt, you continue to amaze me! Who would have thought.... moisture in pots!
I saw your board removal instructions and it sounds like I have a game plan!
If I recall correctly, I think this machine had the same issue when I first got it ( had been stored outside at the seller's house ) and it went away on its own, ( after I stored it indoors for a few months ) so it makes sense that the issue has now returned after being subjected to close to 100% humidity for a week+
Can't wait to see what my wife says when she sees me baking electronics in the oven.

 

[Ray70]

The other interesting thing is that this machine has just over 100 original hours on it and someone at some point covered every single electrical connection inside it with clear silicone. Seems like someone already had an inkling that there was a moisture related issue somewhere, they just went down the wrong repair path.

 

[Light in the Dark]

Gotta say Kurt, you continue to amaze me! Who would have thought.... moisture in pots!
I saw your board removal instructions and it sounds like I have a game plan!
If I recall correctly, I think this machine had the same issue when I first got it ( had been stored outside at the seller's house ) and it went away on its own, ( after I stored it indoors for a few months ) so it makes sense that the issue has now returned after being subjected to close to 100% humidity for a week+
Can't wait to see what my wife says when she sees me baking electronics in the oven.

Hopefully its "want another beer, honey?"

 

[kloppk]

For those interested here is the procedure to get the board out of the inverter.

Remove all the perimeter screws from the top panel and remove the panel.
Top panel removed.


Remove all the perimeter screws from the side panel and remove. There is some sticky foam tape by the connector openings.
Just pop the panel off. Side panel removed.



Remove these three screws at the bottom of the main board.



Unplug this ribbon cable


Unplug the three connectors from the top edge of the main board



Remove these three bolts and nuts



Now lift the bottom of the board up a bit and swing it partly away from the inverter



Now unplug the two cables plugged into the back of the main board



Once unplugged snake the board out


Done. Blue and white items are the pots.

 

[kloppk]

The other interesting thing is that this machine has just over 100 original hours on it and someone at some point covered every single electrical connection inside it with clear silicone...

I've run across several of them that had either RTV or Dielectric grease on every electrical connection.

 

[Guyfang]

This is the most hated gen set in the inventory. One CECOM LAR told me, "The smallest set we have, the most problems of any type, hands down." It can be fixed. It can be improved. But you expect more from a gen set that was bought ten thousand times for the military.

 

[Ray70]

Agreed... I'm not overly impressed with them either, but I bought it along with several 802's and an 803 from a private "collector" in PA.
I just wanted to try one out and see what they are all about, but now I figure I may as well hang on to it incase I need something small to transport or to run through the night with light loads.
Of course I started it up today and now it runs fine.... but I will still keep Kurt's suggestion of sealing the pots in the work Que.

 

[ECS]

Interesting, so was it the Fault control panel that you dried out, or just the control box in general?
My 831 was running fine ( other than a governor controller issue that Kurt is generously assisting me with ) a couple days ago, but today it starts and 4 seconds later trips the overload, consistently.
It has never been rained on, but the weather here has been 90+* and close to 100% humidity for almost a week.
Suppose my first step should be to make sure the high humidity isn't causing the problem!

It was the whole control area like 69birdman pic's have above that I took a hair dryer to it.

The fault was tripping from high humidity.

That is if it's running and a humid down pour the machine it hot and runs fine, but when trying to start it it has issues sometimes when humid.