MEP 805B low frequency/hertz

[JW929]

I am new to these generators and have limited knowledge of things electrical. Any help would be greatly appreciated.

I recently purchased a MEP 805B. It’s wired 208 60 hertz single phase.

The volts are 211-215 but the hertz stay around 42-43. There’s a toggle switch on the main panel to increase the hertz; however, the hertz/rpms do not increase. Additionally, it does not increase the rpms when under load.

Any suggestions on where to start? I need to increase the hertz so things will run properly when running off the generator.

Thank you in advance.

 

[Coug]

First step would be to verify with a multimeter that the frequency is actually what the display is showing.

After that I would check the TM in the troubleshooting section and follow the flow chart for "CIM DISPLAY SCREEN VOLTAGE GAGE INDICATES VOLTAGE, BUT FREQ GAGE IS OFF SCALE". Basically says "check for breaks or loose connections in the AC circuit" and to refer to some schematics that are also in the manual.

Manuals are here:
https://www.steelsoldiers.com/showt...ou-need-to-work-on-the-MEP-805B-Generator-set

 

[JW929]

Coug, thank you for the information. I suspect the frequency/hertz reading is fairly accurate. I plugged my motor home into the 30 amp breaker I installed and it wouldn’t throttle up under load. The two air conditioners would only run at roughly 1/2 capacity and the generator was showing only 1000-2000 kilowatts being generated if that makes sense. The two 110 outlets on the front of the generator work just fine.

 

[Coug]

My guess would also be the meter is accurate most likely, but verifying the problem to make sure you really do have a problem and not just a bad gauge reading is pretty standard for working on any generator.

While the TM mostly talks about it being a possible wiring issue (for unit level repair) there's also the chance it could be whatever the throttle mechanism used on this unit is stuck or out of adjustment in some way. Like I said before, never actually seen one of this unit before, but for the most part diesel engines all share basic common parts required for them to work. Either it's an electrical issue telling the engine to run slowly and the voltage regulator is correcting for the low output, or the mechanical portion of the throttle/governor is sticking/stuck/out of adjustment and needs fixed. That's a bit of an over simplification of things, but it's something to think about.

 

[Coug]

side note, using anything with electronics in it or motors when a generator is running at the wrong frequency has a decent possibility of damaging things. Many items are designed specifically to use 60hz from the utility company's power for regulating internal electronics stuff and the wrong frequency can cause overloads or other issues.

Best thing to use for a load is some type of heater without electronic controls, as resistive loads like heater elements don't care about the power other than it's there and close to the voltage it's rated for or below. (under doesn't hurt, overvoltage can be bad though)

 

[JW929]

I really appreciate the advice. I will check the things you have mentioned. One thing for sure, this generator has a lot of electronics. There is a limiting strap on the throttle by the electronic actuator. Not really sure why it would have a strap limiting the throttle unless somehow the electronic actuator takes over and is responsible for the throttling up when under load. I wish I knew how to post some pictures to help explain what I’m talking about.

 

[Dock Rocker]

I really appreciate the advice. I will check the things you have mentioned. One thing for sure, this generator has a lot of electronics. There is a limiting strap on the throttle by the electronic actuator. Not really sure why it would have a strap limiting the throttle unless somehow the electronic actuator takes over and is responsible for the throttling up when under load. I wish I knew how to post some pictures to help explain what I’m talking about.

You could post a picture of it.


Sent from my iPhone using Tapatalk

 

[JW929]

I attached one picture that shows the limiting strap in the lower right corner of the picture that shows the electronic actuator and one that shows the load when I had my motor home plugged in. Hertz were at 43 and kilowatts were at 1000.

 

[155mm]

https://www.steelsoldiers.com/showthread.php?164332-2-MEP-805B-oh-the-joys&highlight=

 

[155mm]

read that link, i dropped a pickup on my hand so i cant type.

 

[155mm]

start at post 43

 

[155mm]

Coug, thank you for the information. I suspect the frequency/hertz reading is fairly accurate. I plugged my motor home into the 30 amp breaker I installed and it wouldn’t throttle up under load. The two air conditioners would only run at roughly 1/2 capacity and the generator was showing only 1000-2000 kilowatts being generated if that makes sense. The two 110 outlets on the front of the generator work just fine.

805b wont throttle up, it will sound the same at 1kw as it does at 33kw. engine speed only adjusts hertz,

 

[JW929]

Well then the hertz aren’t increasing. The hertz should be at 60 and it’s only fluctuating between 42 and 43. From what I’m told that’s not good on a lot of motors. I was told I could burn the motors out if not operating at 60 hertz.

I’m not an electrician by any stretch of the imagination. I know the basics at best. That’s why I’m trying to see what I should be checking to see if I can get the hertz to increase to 60. The toggle on the panel is not working when I try and toggle up/down the hertz.

The voltage toggle works, but not the hertz toggle.

 

[155mm]

Did you read the thread i posted starting at post 43?

 

[JW929]

155mm. Thank you! I finally found post 43. I had to go to the full version of the site to see the #’s. I vaguely recall seeing speed trim (or something to that effect) on the back wall of the circuit boards when I flipped the front panel down. I will look at that in the morning. I will try adjusting that and see if I can get the hertz to increase. Thanks again for your help! Greatly appreciated!! I will post tomorrow after I have tried adjusting the speed trim to let you know if it worked.

 

[155mm]

go Ez when adjusting, rheostat only goes from 7 thru noon to 5.

 

[155mm]

Looks like wide open throttle skrew has been dinked with, might check that also



please ground genny while working or operating

and test magnetic pickup while in there

 

[JW929]

I was just getting ready to ask you if that was the screw in the second pic.

I’ll check that as well. It sounds like it’s at idle when it’s running.

Sorry I don’t know much about the generator. I just got it a few weeks ago. One of the stickers on it says it was rebuilt and there’s only about 10 hours on it since the rebuild.

 

[155mm]

dont trust hour meters, i edited previous posts, reread.

 

[155mm]

wide open throttle should be 65hz