15kw MDJF over voltage output problem.

[MarioG]

This weekend I had some minor problems with our genny. over all it ran well. I did notice that the generator aperently is producing excessive voltage. the meters are indicating well into the red arc reguardless of loading. recently, I had one injector rebuilt due to bad fuel. I also removed the flywheel and changed the ring gear due to uneven wear, in doing so I removed then replaced the spring next to the flywheel which i beleve has something to do with the governor.

any ideas why the over voltage and how to fix the problem?

 

[Boatsb]

Voltage is directly related to the RPM's and the spring thing is part of the governor.

Basic adjustment is to adjust it to about 117 Volts. Popper is to get a frequency and adjust it to 60 htz.

 

[Pascal]

normally RPM controls frequency NOT voltage... not very familiar with Onans but that's the way it is with most gennies.

voltage is usually controlled by a voltage regulator, there might an adjustement. You really need to check RPM-frequency with a meter if you dont' have one on the panel.

How much voltage do you have?

 

[Boatsb]

Too high an RPM will increase the voltage. How high is the right question.

 

[Avenger]

If the governor spring was changed, speed needs to be reset first. RPM is used to set frequency only. Mario needs to either put a frequency meter or a photo-tach on it. Set the governor to 60 Hz or 1800 RPM then re-check voltage. If it's still out of range then it's either the regulator or other electrical issue.

 

[REBrueckner]

Sounds like the genny is now running at a higher RPM than before your changed the governor control spring....it should have an adjustment nut...I'd guess loosening the nut to extend the spring will solve your problem since likely a new spring is "tighter" (shorter) than the old...try a quarter or 1/8 turn at a time while genny is running under load and see how much effect it has on voltage....

 

[LIBERTY]

Mario,
As I recall, there are actually two springs performing a balancing act to keep the frequency and voltage in spec while at the same time eliminating surging of the generator at varying or high loads. A meter with frequency as well as voltage is required. I have the tuning directions from the manual on the boat if you need them.
Bill

 

[MarioG]

Thanks for the replys guys! I'll check the check/adjust the spring and see what it does and report back.

Thanks.

 

[Nonchalant1]

Too high RPMs will increase voltage and frequency. The correct way is to adjust RPMs with a frequency meter to get 60Hz and then adjust the voltage at that RPM by turning a pot on the control board.

However, if your control board was set OK before, it probably still is and you can just adjust it to get 60 Hz and I'll e the voltage will be fine. If you have a photo tach, start out at 1850 RPMs to try it.

120-125 volts is good these days. Some adjust it a little higher to offset voltage drops as new consumers come on.

Doug Shuman

 

[SKYCHENEY]

If you don't have a frequency meter in your panel, you can buy them that just plug into an outlet. I have on at home and it works great. Here is a link to the one that I bought.

http://www.discountpv.com/meters/p4400.htm