In need of Onan electrical end

Yep that would be the reason to replace it. I replaced the engines 2 yrs. ago and should of done the generator at that time but had allready spent way to much $$$$$.

That's your best bet a lot of times. When you fix and rebuild 20 year old junk, you tend to still have 20 year old junk.

P46- What did you decide to go with?

I ak going with the 9kw Cummins/Onan. In the same ball park price wise. Waiting on install cost as we speak.

The Cummins/Onan is a great choice in that size range and a rock solid generator. Another great choice would be a Northern Lights. Wear parts are much cheaper for the Northern Lights. In your location I'd stay away from both Westerbeke (their new electronics are troublesome) and fisher panda......

Onan Front End

Hi Guy's,

Thanks for all the info on the generator discussion. My Onan 8KW front end is all tapped out, meaning I can't get any higher than around 108VAC out of her. The engine is still doing great. Please let us know how the installation goes on the new genset. Anybody have an idea on how to crank more voltage out of the front end?

Thanks a lot
David

If you're talking about a 125volt generator then yes. The engine is not spinning the electrical end fast enough. You need to either do a tuneup on the motor, if diesel adjust valves, check injectors, then raise the adjustment on the governor till you get 125volts and 61 hertz.........The engine needs to turn more rpms basically.

Onan Front End

Hey Capt J
Thanks your response sounds like a good possibility. I was looking at the taps and found that they are all set to max voltage.
Yes it is a 125V and a diesel. I think I will first check the rpm against the spec and see where she is running. I dont have the service manual, just the operation, installation and parts catalog. I will let you know what I find.
Thanks again.
David

Thanks P46 but I don't understand what 12V's would play other than starting the engine. I was thinking my transformer taps could be moved to crank up the voltage a bit but I found that I am already using the max taps available on the transformer. I will look into the RPM's of the engine and make sure I am spinning her fast enough.
Thanks
David

Whoa, hold on there bubalooie,
Engine speed sets the Hertz of the ACv cycle (as in 60 htz), NOT the voltage output. Verify the rpm of the block at 1800 rpm. If your still low ACv, then there is other problems.

108ACv based on a small panel volt meter or a real DVM? AND in a hand held DVM, is that RMS or total swing?
108 ACv is near RMS of total swing. is why I'm asking.

Also, does your ACv clocks hold good time while on the generator? Good indication if the 60htz is close on the gen-set.

I need to ask, to ensure I'm on the correct page, what taps are you talking about?
Transformer excited taps inside the gen-set? External isolation transformer & taps next to the gen-set? Or AVR jumpers on the gen-set?

On later generator ends, you can kick-off the exciter field by applying 12DCv. This should drive the output near 120/240ACv unloaded. I think that is what P46 was trying to refer to.

,rc

The faster the electrical end spins (even though voltage is determined by the number windings in the electrical end, the faster you spin it, the more voltage you get......if the motor isn't turning fast enough, then you will have both lower voltage and lower hertz (with a load).

We may need to open another thread here. Following P46 AND helping Davidoc.
I guess were waiting for Davidoc to verify rpm.

The meter used to measure the frequency and voltage is my Xantrex 3KW inverter. The panel measures both precisely. The frequency has held at 60-61Hzfor many years but the voltage has gradually gone down from 120 to 107 or so. Periodically I will get a warning from the inverter that the voltage is low. I have set the warnings to low on that device.

The taps are inside the genset. There is a chart in the book to move the taps up or down to increase or decrease the voltage output to the loads. Mine are set at the max increase but I still only get 108VAC or so.

I don't see any reference to a 12V exciter in my diagrams. I dont think I have that but I think I could sure use it. My genset is a 1990-91. 8KW