Mep003 voltage drop after 7500w

This unit will run my 7500w heater for hours. If I add 1300 more watts my hertz goes from 60 to 63, volt drop from 240 to 140 then up to 180, load% from 55% to 30%.
When adding the extra load it seems to electrically drop then pick up drop pick up.
The engine runs strong and does not bog down.
Breakers do not trip
When I go back to 7500w/55% load everything goes back to normal and runs great.
I’m not sure where to go from here

The voltage crashing leads me to believe there is a failure in the AVR.

Basically the higher load requires a stronger field and the avr is not keeping up causing the voltage to crash. This in turn causes less magnetic field and makes the rotor spin easier causing the spike in frequency.

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@Scoobyshep are you talking the voltage regulator? I have a new ac vr installed in the control box.

Dog Breath said:

@Scoobyshep are you talking the voltage regulator?

Click to expand...

Yes.

Avr= automatic voltage regulator

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This control box has a new avr from kloppk. I could switch avr’s from another unit to check

He would be the better resource here. If it were me and I were troubleshooting I would measure the field voltage and observe it as the load is increased

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Ok I will figure out how to measure the field voltage. My electrical knowledge is limited

@kloppk is the expert.

If it were me, I would double check the wires and the wire terminals to wire connections to be sure that there isn't some loose wire(s) or internal corrosion that is causing extra resistance, and overloading the AVR. I would also give the entire field wiring circuit from the AVR to the gen head a close look for any suspicious looking portions. (Fraying, burned spots, etc.)

All the best,

2Pbfeet

I was just going to say the same thing, Check for loose wires and contact Kloppk. Too me it sounds like a loose wire that just can't carry the field load after a certain point.

I checked all wires in the cubicle. Nothing loose. I exchanged cubicle with another working 003 and it works as it should 70% load 8800w with no issues. So I will have to dig into the bad cubicle

Well I hooked up the bad cubicle to the other 003 and I’m getting 53 volts at the convenience receptacle and L0/L1 and L0/L3 both 53 volts I will clean connections tomorrow and do some testing.

Unlike other generators the AC Voltage Regulator in the 002, 003 does not directly drive the exciter. It does it indirectly via the CVT and other components.
Here is an excellent video on how the voltage regulation system works.
YouTube Video

You may want to swap the AC VRs between the two boxes and see if the issue is the VR itself.

I will switch vr’s later this afternoon and make sure all contacts are clean and report back. Thankyou

kloppk said:

Unlike other generators the AC Voltage Regulator in the 002, 003 does not directly drive the exciter. It does it indirectly via the CVT and other components.
Here is an excellent video on how the voltage regulation system works.
YouTube Video

You may want to swap the AC VRs between the two boxes and see if the issue is the VR itself.

Click to expand...

Thanks for sharing the video link! That video is a fascinating and very informative look at the rather sophisticated (I think) control system. It seems quite clever, and definitely an unusual solution in my experience. Do you have any insights about why a magnetic control system was used? Reliability?

All the best,

2Pbfeet

kloppk said:

Here is an excellent video on how the voltage regulation system works.
YouTube Video

Click to expand...

Also note that this debunks the idea that running the engine at a speed below 1800 RPM can damage the regulator. Doing that makes the regulator put out less current to CVT1, which reduces its load.

2Pbfeet said:

Do you have any insights about why a magnetic control system was used? Reliability?

Click to expand...

If the regulator fails, the generator can still have output, although it's likely to be at a higher voltage than normal. But at least it doesn't cause an immediate power failure.

Triple Jim said:

Also note that this debunks the idea that running the engine at a speed below 1800 RPM can damage the regulator. Doing that makes the regulator put out less current to CVT1, which reduces its load.

Click to expand...

On this set. The bigger brothers work differently

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Scoobyshep said:

On this set. The bigger brothers work differently

Click to expand...

Most other generators in the world work differently. It's our 002A and 003A generators that use the mag-amp system and can be idled as long as you like without damaging the regulator.

Triple Jim said:

Most other generators in the world work differently. It's our 002A and 003A generators that use the mag-amp system and can be idled as long as you like without damaging the regulator.

Click to expand...

I took advantage of that fact several years ago due to 120v present at the utility receptacle.. Had an evening field task requiring intermittent hole drilling with 15-minute pauses in between .. Yes the drill motor ran slower due to genny not even reaching 50cy output at an idle , but the slow speed was welcome for what i was drilling .. I didn't want to start-stop the genny every 15 minutes, nor wastefully run it at normal rpm .. Afterall it was my rig now and not the army paying for everything

Anyway, when it got dark i plugged in a flourescent drop light to finish the job and it worked just fine.. A half-hour later when i finished and was picking up to go home, the light fizzled out with an awful smell ... The little plastic transformer box on the end of the lamp cord had warped and apparently didn't like being low-cycled... ooopss !

That experience has prevented me from trying this trick with the flourescents in my M750 parts storage trailer , but someday i might try it with the incandescent bulbs that are separately-switched in there .. they would probably flicker like mad but i don't know

An update on my issue. After switching control cubical the problem goes with the cubical. Same issues different 003. Next I switched the vr between generators with the issue following the vr. I sent the suspect vr to @kloppk to test and repair.


I did pick up two more 4000w heaters cheap and ran a load test to 11,500w on the 003 with the good vr for 30 min without an issue. I did try adding 1500 more watts but hertz dropped. I have plenty of engine left but the governer won’t compensate that much.

I think this is amazing considering both of these units sat in the weather on a trailer for who knows how long and we’re rusted tight