MEP-003A Unstable Hz problem. Any ideas?

[Spooledup]

I did a search for unstable/fluctuating Hz readings and couldn't find anything.

Here's the story. I got my -003 running last week. It runs great, puts out steady voltage, and at first I adjusted the RPM to make 60 Hz. As it ran over the course of the next few minutes without a load or even the circuit breaker turned on, I noticed the Hz had gone to 65. I turned the RPM back and I could only get it to go to 62 or so and the cable was all the way in. It didn't sound like it was idling either.

Thinking it maybe might be a Hz gauge/transducer problem, I bought one of those digital Hz/Voltmeter gauges from Hardy Diesel for $20. I installed it and tried running it again today and I got the same result. Hz creeped up to 63 or so and pushing the cable all the way in didn't get it any lower than 62.

Does it need to have a load on it in order for it to make 60 Hz?

What controls the Hz output that could cause it to change with the same RPM?

Thanks for the help.

-Dave

 

[Isaac-1]

It sounds like you may need to adjust the governor on your generator, I have never done it on a MEP-002 / MEP-003aa so I will leave it to others to chime in. (instructions are in the TM). As to the frequency rising as the generator warms up, I too have seen this on my MEP-002a and other diesel generators with mechanical governors. In my experience it seems that they will go up 2 or 3 HZ after the engine warms up then stabilize, I am not sure of the cause, could be metal expansion in the governor linkage, or oil getting thinner as it warms up, etc.

Before you do anything though, I would suggest putting a load on the generator and see where the frequency stabilizes, most mechanical governors have 2-3 Hz worth of droop between no load and full load, therefore they are generally set for around 62 Hz +/- at no load to allow dropping to 58-60 Hz at full load.

Ike

p.s Hz is directly linked to RPM 1800 RPM = 60 Hz on a 4 pole generator

 

[jeepin]

Spooledup
It sounds like there might be a linkage problem because with the cable _all_ the way in the set should almost be at idle (and if you have read the site you know not to idle these gensets because it can burn out the AC regulator). Remember the cable isn't directly connected to the arm on the injector, there are a series of springs and linkages to govern the engine at a constant speed. Unfortunately the cable itself ends up inside the fairing and it is hard to see/touch without pulling whole front fairing. But you can see the linkage on the side of the injector pump and check that. Sounds like you are assuming the RPM's aren't changing but without a tach you must be doing it by ear, as loud as these sets are I am not sure that is accurate.

 

[Triple Jim]

What controls the Hz output that could cause it to change with the same RPM?

Frequency can't change if the RPM does not change, because they're tied together. The four-pole alternator is directly coupled to the engine, so you get exactly 60 Hz AC when the engine is running at 1800 RPM. If the AC frequency is changing, then the engine speed is changing.

 

[sewerzuk]

Frequency can't change if the RPM does not change, because they're tied together. The four-pole alternator is directly coupled to the engine, so you get exactly 60 Hz AC when the engine is running at 1800 RPM. If the AC frequency is changing, then the engine speed is changing.

x2 what triple jim said. Engine RPM=frequency. The ONLY thing that changes frequency is a change in engine RPM.

With that being said, I would suspect that you just have sticky linkage. Spray liberally with penetrating oil, cycle it through its full range of motion. It should move very easily with the solenoid held in the "up" position. If it doesn't, you may need to remove the IP to clean the shaft inside of the pump.

 

[DieselBob]

Checkout TM5-6115-585-34, Chapter 7, Sec 7-3. It goes through the throttle cable and governor adjustment. Mine always starts out running a little fast but given 5~10 minutes to warm up, depending on the outside temp it settles back to where it was last time I ran it. I haven't moved the throttle in or out sense last time I cleaned lubed and adjusted it last year.

 

[Spooledup]

Thanks very much guys. I'll start working on all of this and let you know how it turns out. I appreciate it.

-Dave

 

[Heath_h49008]

Any of you guys rig these up to inverters to clean up the output wave form?

 

[Harleyd315]

I had an 003 that would start at 1800 rpm with the the throttle cable all the way in. It was a rebuilt unit and I thought maybe the military did this to stop burning up regulators. I never got to figure out the way it was adjusted (sold it during Sandy). I would definately check all the cable, linkage adjustments and lube everything.

 

[steelypip]

Any of you guys rig these up to inverters to clean up the output wave form?

You mean use the gen set to clean up the inverter wave form? Nope, but it might work. I don't know how you'd keep the two synchronized, though. If you want to clean up an inverter output, a better, cheaper, and more efficient solution would be a ferrorresonant transformer (basically a normal transformer with a second output circuit wired as a resonant tank circuit). They're over 90% efficient and are ideal for both waveform smoothing and voltage regulation. I have a small one (200 W or so) salvaged from an instrument rack some years ago and I love it. I'd be really happy if I could find a 2kw or so sized one as salvage.

 

[Spooledup]

Just an update on the Hz problem I thought I was having.

My Dad and I got the 003 hooked up to the house last week and finally put a load on it. Had to take apart the big switch under the cover (beside the circuit breaker) because it was locked in the single phase 120 position. Once we got that sorted out, I plugged her in and we connected it to the house. With the load on it, it ran steady and once I set the Hz on 60, she stayed there for the duration. I had the oven, hot water heater and well pump and a bunch of lights running at the same time and it was showing a 75% load. We ran it for about 15 minutes and the oil pressure only dropped to just below 40 psi. I was expecting lower.

I have a friend that has an MEP-002 and his seems louder than my 003.

I'll post some pics in a few days showing how we hooked it up.

Thanks for all the help and I'm always impressed with the great info on here!

-Dave