Generator help please

[veggie]

Yesterday I ran my Slow speed Changfa to hear the newly installed muffler.
When I applied only 900 watts of load to the generator, the engine nearly died !
This is the same engine that was pulling 3 kw's at this speed one week earlier.

Every time I added any load at all, the head made a whining sound and the engine bogged down.
I removed the belt and spun the head by hand but I could not hear (or feel) any bearing problems.

Did I fry a winding      HELP !!

veggie

[mobile_bob]

sounds like a generator problem to me

when it bogs down, does the engine exhaust start to turn black?

have you tried the other heater? perhaps the heater you are using has a short?

bob g

[BruceM]

Some measurement of generator voltage and current would help.  Bob's suggestion of a shorted heater sure fits well. 

[veggie]

Will test the accessories and report back.

veggie

[mobile_bob]

i only mentioned the heater as a possible source of the problem, based on my being bitten more
than once with something painfully/stupidly obvious, only after spending mucho time and money
looking at everything else.

an example for your entertainment

example #1
as a kid i had a '64 impala, nice rod, that one day developed a bad miss and backfire
bought new plugs and wires, then cap and rotor, then coil, the resistor block, then worked over the carb
and finally thought i was fixed,, the problem vanished
about a week later while cruising with my buddies, it starts in again, we pop the hood
and because if was dark i could then see the wire that comes off the relay post of the starter solenoid
to energize the coil with a full 12volts at startup was laying against the back of the exhaust manifold
shorting intermittently taking out the ignition system. all it took was rehanging the wire over the tap support
on the firewall.
that only cost me about 250 bucks in parts, at a time when you could buy a car for less.

example #2
a cabover IH truck with a VT903 cummins, i reach up and remove the alternator, it is hot as hell under the cab
and access is tough,, i pull the alternator because it is not charging, tear it down, inspect everything can't find
anything wrong, so  i put in another regulator, and go to reinstall it..... ooooops

where are the belts???

in my haste i had not seen that the belts had been missing from the start!

in my defense i was only 19 at the time, and learning the trade, but it was something i got a lot of ribbing about
and never forgot.

moral of these stories?

sometimes it is the simple things in life that drive you nuts



bob g

[BruceM]

I had a very similar "generator" problem as Veggies.  My homemade AVR was shutting down the generator just as I was in a hurry to set up two thermal glue guns. Ultimately I found that one glue gun was a near short, and it would lug down the Lister until the the AVR kicked off the generator for low voltage, and when I bypassed the AVR and ran on Harmonic excitation,  the Lister controller would shut down the engine for low rpm.  

It took me a while to catch on to real source of the problem, I refuse to say how long!

[RogerAS]

Could the new muffler be adding too much restriction to the flow? Have you tried without the new muffler?

RS

[veggie]

Could the new muffler be adding too much restriction to the flow? Have you tried without the new muffler?

RS

Roger, that had occurred to me because it's the only thing I changed since the previous run.
My attention was drawn to the generator head because of the loud whining noise it was making.
The muffler is a 2" inlet from a 4 cylinder car. I don't think the back pressure is causing it, but as Bob suggested, you can't rule out anything. I will add the muffler to the list of things to investigate.

thanks,
veggie

[vdubnut62]

Could the head have been whirring already, just covered up by exhaust noise? Not saying that this is what's going on, but
I inadvertently reversed a muffler once, it acted like a checkvalve! I finally figured it out when the muffler blew it's fiberglass innards out.
I gave myself the "DOH!" award.
Ron

[TimSR2]

What is the diameter and length of that flexible exhaust?  Disconnect it and try the test again. The generator core growl is not really cause for concern

[WGB]

Thanks Veggie! thats the generator you talked me into!  

Mine whined out of the box, works fine.
I was wondering about the whine being covered up before like Ron.
If your hearing is like mine, I don't hear some frequencies very well.

[Halfcrazy]

My gen head came from cmd and looks similiar and whines like a stuck pig always has? I have just ignored it for now I am sure it will fix itself 

[veggie]

What is the diameter and length of that flexible exhaust?  Disconnect it and try the test again. The generator core growl is not really cause for concern

The diameter of the exhaust is 2" and runs 11 ft.
I didn't think it would cause a problem being that the throughput of the engine at 900 rpm is relatively low.
Easy to remove for test purposes.
I will add that to my list of things to do when I run it again in a few days.

thanks,
veggie

[veggie]

My gen head came from cmd and looks similiar and whines like a stuck pig always has? I have just ignored it for now I am sure it will fix itself 

I have two of these heads, one whines, and one does not. ?
That's why I got curious about windings.
It's very possible that the whining is ok for this unit.
Will report back after testing.

veggie

[veggie]

**** UPDATE ****

So I tested the induction heaters on a wall outlet with my new kill-a-watt and they work great.
Setting #1 = 750 watts, and setting #2 = 1500 watts. (on both heaters)

I also inspected the muffler and 2" flex hose system.
When the engine was running, there was very good flow and a strong exhaust pulse at the end of the line.

Next step was to apply some load again.
I turned on one of the heaters on low setting (750 watts) and the engine slowed down.
Instead of quickly turning off the heater, I let the engine run to see what happened

Revs dropped from 900 to 750 (now in Listeroid territory   ) and it stabilized there. (sounded lovely by the way   )
I then increased the load to 1.5kw and the revs dropped a bit more (700 rpm).

No black smoke !

I gently applied pressure to the governor lever and the revs picked up effortlessly.
Somehow the governor is not sensitive to the low speed operation and loading.
(This was Jens' assumption when the problem first appeared)

So now I call on anyone who knows about governors and how they relate to spring pressure and adjustments to give me ideas on how to make this system more sensitive at the lower speed.
The linkage is currently free an not binding.

thanks for the help so far.....

veggie