Governor hunting during MEP-OO4A Load Testing

[1800 Diesel]

Just completed a single-phase conversion & have begun load testing. While adding load (at ~70%) I noticed freq meter jumping up and down a little (from 60 to 60 1/2 hz) & I could also hear engine speed changing in sync with the freq changes. Looking at the loads on L1 & L3 I then noticed I had about 20 amps more load on L1. Once I dropped a couple loads off L1, the engine speed & freq stabilized.

My question is: Should that amount of phase imbalance cause such behavior? I'm thinking it shouldn't but also haven't seen this before. Anyone have any thoughts? If not normal, is there anything I can do on the IP to alleviate this? I've adjusted governors on MEP 2 & 3 machines, but not on the MEP4 & I assume there's no external way to adjust sensitivity on this model.

Thanks in advance for any assistance.

Kevin

Edit update: Completed final load testing this evening (right before a mean lightning storm), results as follows:

L1--73.1 amps

L3--73.3 amps

Load meter was pegged beyond 130%.

Loads were quickly removed & added & the hunting problem did not show up! No exhaust smoke could be seen during the test & no oil, coolant or fuel leaks either. I expected a little black smoking but very little could be seen.

 

[PeterD]

I would not panic over a half Hertz change in frequency but what I'd do is run it up with a more balanced load. I bet it does the same thing (hunts) and that you're going to have to do some adjusting of the engine speed setup.

 

[1800 Diesel]

I would not panic over a half Hertz change in frequency but what I'd do is run it up with a more balanced load. I bet it does the same thing (hunts) and that you're going to have to do some adjusting of the engine speed setup.

Morning Peter,

As a follow up, I ended up with a 60/54 amp split which showed up as 120% load on the meter. At first when I started adding 3KW loads in steps, it would start hunting (with each load addition) but after about 30 minutes of running at 120% it cleared up. On the reverse side, as I unloaded the unit, speed fluctuations occurred but they were not as noticeable. Besides checking the throttle cable & linkage on the IP, do you know of any external means to adjust sensitivity? The behavior I'm seeing with this one is similar to an MEP-002A I worked on awhile back--on that one I adjusted the spring position per the TM & that fixed the issue.

Thanks for the assist!

 

[glassk]

Just a thought , make sure the cable and sleeve are free and no binding,

 

[Suprman]

Did you ever figure out what the adjustable screw thing was on the front of the IP? It does seem to control fuel rate.
Will

 

[1800 Diesel]

Just a thought , make sure the cable and sleeve are free and no binding,

Thanks Keith--I'll confirm the cable is free. Just finished changing the two fuel filters & about to prime the system.

There is something of interest that may be related--the fine adjustment knob has no effect on speed. To set correct speed I have to loosen the lock nut & push or pull the cable to the correct position & then I tighten the lock nut.

 

[1800 Diesel]

Did you ever figure out what the adjustable screw thing was on the front of the IP? It does seem to control fuel rate.
Will

Haven't had much time since I've been out of country a few months, but have been looking through the TMs for more details. And since the unit runs under full load & at steady speed, the fuel delivery rate seems good. The problem seems to be excessive sensitivity to load changes on the governor. I just need to figure out if there is an external adjustment for sensitivity or droop. Possibly the knurled knob is the cat's meow but I'm reluctant to touch it until I know for sure.

Thanks

 

[Suprman]

I still have the one I cooked. The IP has a metal wire locking part of the throttle in a fixed position. I always thought the hand throttle was used to make minor adjustments. The Precise versions have a solenoid control in the place of the metal wire to keep the gen more stable. I think the fluctuations you describe are just the nature of the beast.
Will

 

[1800 Diesel]

I still have the one I cooked. The IP has a metal wire locking part of the throttle in a fixed position. I always thought the hand throttle was used to make minor adjustments. The Precise versions have a solenoid control in the place of the metal wire to keep the gen more stable. I think the fluctuations you describe are just the nature of the beast.
Will

Will,

I believe I discovered the culprit. In addition to the main load coming off my distribution box, I had an additional line connected to L3 which was not being turned off via breakers but only if I turned off the main breaker on the unit. So every time I removed the main load there was still about a 4KW load on L3 only. This was enough to cause the hunting. If I quickly matched the load on L1 the hunting ceased. In order to verify, I repeated the scenario several times with the same result. Engine control remained stable when unloaded 100% or when loaded 100% or more...to clarify, obviously engine speed was reduced somewhat or increased as loads were removed or added, but no more hunting....

Thanks for everyone who chipped in! Road trip in the morning.

 

[PeterD]

...
There is something of interest that may be related--the fine adjustment knob has no effect on speed. To set correct speed I have to loosen the lock nut & push or pull the cable to the correct position & then I tighten the lock nut.

Humm, that's not good (though I don't think it is your main problem.) My fine adjust on my 004 works as expected, so I think you should check that cable and the knob assembly out some. There are some adjustment(s) on the injection pump--I've never done much with them. However, the throttle cable should not cause speed hunting. Oh, and make sure that second 'arm' coming out of the injection pump is properly safety wired in the correct position--if it moves you might get some strange effects.

 

[1800 Diesel]

Humm, that's not good (though I don't think it is your main problem.) My fine adjust on my 004 works as expected, so I think you should check that cable and the knob assembly out some. There are some adjustment(s) on the injection pump--I've never done much with them. However, the throttle cable should not cause speed hunting. Oh, and make sure that second 'arm' coming out of the injection pump is properly safety wired in the correct position--if it moves you might get some strange effects.

The shutoff lever is in correct position & safety wire is in place.