MEP-002 frequency question

[lostkid]

I have an 002 that is (now) running fine engine wise but is not producing a consistent 60hz. The voltage seems fine and stable. The meter on the control panel gets to 60hz, but when I put an external meter on the convenience outlet it shows about 52hz and the engine rpms don't seem high enough. (I should say that I have rebuilt several 002's and 003's and am quite familiar with them). As I increase the rpm's the external meter is stable until about 57hz, past that and it's all over the map. I've tested the meter in other gensets and the house and it's working properly. The frequency transducer is connected directly to the panel meter so I'm thinking that isn't it. I'm thinking the transformers in the control box or maybe the voltage regulator may be possible suspects? I would welcome any thoughts, thanks.

 

[Isaac-1]

Some, particularly cheaper, meters don't read frequency very well on generators, due to distorted waveform of the output. Sometimes adding a resistive load while running will help stabilize the readings, try a 100 watt conventional light bulb. If that does not work try using a different meter, the cheap kill-a-watt meters usually do surprisingly well at measuring frequency. You may also have a loose connection in the breaker, etc that is vibrating at a certain resonance.

Ike

 

[Carl_in_NH]

If the engine speed isn't bounding around wildly but the external frequency meter is, then it's an artifact of the meter - not the generator going wild.

Try what Ike suggests - or use another meter for your measurement.

 

[lostkid]

Thanks for your input. The meter, as I stated in the original request for ideas, reads dead on when connected to my other 4 generators (002's and 003's) as well as household current, so I'm confident the meter is fine. This is the reason for my question, I have 4 that work and one with this odd condition. The engine speed is stable and it'll power lights just fine. I, like many of you on SS want things to be right and this isn't so I'm hoping someone will have the answer. Thanks for your input.
Pete

 

[signmaker]

Take the meter out of the control panel hook it up and hold it in you hand then run the genset.

 

[Isaac-1]

My understanding of modern digital frequency meters is they detect the zero plane crossing, most of the time I hear about false readings on generators it is on brush style generators making poor connecitons, or 3600 rpm consumer generators with very distrorted wave form. This should not be the case for your generator, however something may still be adding electrical noise spikes causing false readings, therefore the light bulb suggestion. I would also check for bad connections at the breaker and the reconneciton switch, this may be causing the connection to break momentarily that the meter is seeing as a zero plane crossing. Have you tried testing at both the onboard outlet and the output lugs?

 

[lostkid]

Isaac, yes I have tried to meter at both locations with the same result.
Signmaker, the meter on the unit reads, albeit wrong, steady freq.
Maybe I should clarify some more, at idle (about 52hz) up to 57hz my digital meter is steady. As I raise the rpms past that point the digital meter ceases to give a steady read out. My knowledge of frequency is that it's directly related to speed (rpm) and as long as the generator is spinning the correct speed the frequency will be right. Which is why I'm perplexed with this one. I will check the connections more thoroughly. Thanks all.

 

[Carl_in_NH]

Sorry, missed the point about testing the meter on other gensets in the original post, and only noted you'd tested it off the line power.

This is interesting; better test equipment would yield better results. Do you know someone with a scope they can hook up to the genset? Would be nice to see if it's a real sinewave, or something ratty once the speed comes up. Could be a flaky connection powering the field of the genset - that might be RPM sensitive. Also could be a bad rotor coil that starts acting badly above a certain RPM because of centrifical force.

A scope on the output waveform would yield clues more quickly than guessing.

 

[panic_button]

What is all over the map? Mine will diviate .2-.8 on the digital hz. this is with no load or a small load. With it loaded up with the whole house it is about .2hz flux, except when the 5 ton A/C kicks in.

 

[Speddmon]

Plain and simply put, if the frequency is jumping around above 57 Hz, it's either the meter or the engine.

The transformers and the electronics on and/or in the set DO NOT AFFECT the frequency. The frequency is absolutely and soley determined by engine speed. I would venture to guess that if you are jumping around, depending on how much, you probably can't hear the tone difference in the motor. A good external handheld tachometer will tell the tale. I'm willing to be you have a governor droop adjustment problem, and your governor is "hunting"

 

[lostkid]

Carl- What you say makes a fair amount of sense, that'll be my next step. I agree with Speddmon that the engine speed determines frequency. I should clarify another point. The variations of freq. on my meter are very rapid, several changes in less than a second. I've seen the read out go from 42 to 300 then 172 then 58 then 89, etc. all very rapidly. The engine speed can't change that fast. Thank you all again I'm very appreciative of all the continued advice.

 

[Isaac-1]

Do let us know what it turns out to be so it may save the next person some trouble

Ike

 

[milo]

I am having the same issue with my latest MEP 002A. Tom at Gulf Coast suggests it might be the transducer instead of a faulty meter. Let us know what you finally determine.

 

[Keith_J]

Yes, milo, it IS the transducer. How this thing works is the frequency is determined by the transducer, the output to the meter is a direct current which is an analog of the frequency.

The meter is a simple permanent magnet galvanometer. The windings are incredibly fine, probably 0-20 milliamps with the 60 Hz being 10 mA. Output of the frequency transducer would be a nice thing to know for certain.

Mine on my 002a got water intrusion and rusted out. The back bearing for the needle is secured to a zinc bar, the water caused grain warp and the bearing adjustment isn't possible. So it is a $100 replacement.

ETA: I've found 3-1/2 digit displays in both voltage and current. A simple voltage/current divider could be used to condition the frequency transducer output to display correct frequency, DIGITALLY. The cost of these digital gauges is under $10.