Genset grief - Help

[jaoneill]

I could use a bit of help with my latest dilemma. Power went off last night and the way the sky was lit up with arcing electricity off to the northeast it was a sure bet that it wasnt going to be a 10-minute outage, so I fired up the genset. We have a 5k military unit powered by a 2-cylinder Onan diesel with just 2k hours on the clock; it's a slow turner (1800 rpm) designed to run continuously for weeks on end. It is more than adequate for all of our needs (usually runs at 15% - 25% capacity) and absolutely sips fuel. I woke up about midnight and we had lost power. Went out to the mechanical room and found the diesel barely idling and surging somewhat; a classic fuel issue. The fuel filters had less than 100 hours on them, as did the three electric lift pumps that I had replaced a couple of years ago. Traced it back to a screen in the fuel tank that I had no idea was there, easy enough to remedy. Fired it up, warmed it up, flipped the electric switch and nothing happened, as in zero, zilch, no power. I did notice last night that when I first fired it up, I adjusted the throttle to get the frequency at a stable 60, but in spite of turning the voltage rheostat all the way up, I couldnt get voltage over 110 although it usually runs at 120 in the three quarter position. Any suggestions as to what the issue might be?

This post was edited by jaoneill on 12/12/2021 at 02:20 pm.

 

[Billy Shafer]

Get me the TM number of the unit. I may have the service manual.
Trouble with military units. All the systems work together. One bad
section and it affects them all.

Five years Battalion MSGT 249th Signal

 

[K Effective]

Billy is clearly the expert here on generators, but
I'll toss in my two pennies. From what you have stated it almost sounds like you need to flash the field. Is there a button on the control panel to that effect?

 

[jaoneill]

Here you go.... If the numbers you need have been obliterated by the flash, I can try another angle.

This post was edited by jaoneill on 12/12/2021 at 03:29 pm.

 

[jaoneill]

I've searched hi & low looking for something like that, to no avail. But, then again I'm not really sure what I was looking for. Our power was out for two months back in '98 and has been problematic ever since. I installed this baby about 20 years ago and have never had an issue. Since then we have had a couple of 1-2 week periods with no utility power and a lot of 1-2 day outages. I keep a maintainer on the batteries and fire it up every six months or so if we haven't had any outages. It has always just worked..... it's been a Godsend, until last night

 

[Steve@Advance]

Did you look at the slip rings?

Possibly the brushes are stuck or mud dobbers built on them.

Look for the obvious first, a bad connection, mouse chewed wiring. Anything that
looks to have been hot or corroded.

 

[jaoneill]

(quoted from post at 23:29:16 12/12/21) Did you look at the slip rings?

Possibly the brushes are stuck or mud dobbers built on them.

Look for the obvious first, a bad connection, mouse chewed wiring. Anything that
looks to have been hot or corroded.

I'll start there tomorrow, thanks, much appreciated....

 

[Billy Shafer]

A better picture would help. But I can make out the NSN number as
6115-00-465-1044 PF0.8. What is it set up for now? 120 1 phase or
120/240 1 phase.

Made in 2/91 with field support inspection 8/91. Sort of odd may have
had problems before.
Solid state unit does not have brushes.

 

[Billy Shafer]

I have your manuals. Parts and service. Been a long day. I am going to bed.

 

[jaoneill]

(quoted from post at 01:33:56 12/13/21) A better picture would help. But I can make out the NSN number as
6115-00-465-1044 PF0.8. What is it set up for now? 120 1 phase or
120/240 1 phase.

Made in 2/91 with field support inspection 8/91. Sort of odd may have
had problems before.
Solid state unit does not have brushes.

Thanks Billy, I have it set up for 120/240 single phase.
Here is a better shot of the name plate. Our internet connection has been coming and going since the wind storm Saturday night so my responses are delayed. I received a tabbed binder with the unit that has the sales and ownership documentation and copies of various sections of a manual with some parts listings but mostly pertaining to the engine. The sections that do reference the electrics mostly just say to make certain the connections are tight and/or not visibly fried. Thought I might open the control panel later and have a look.

 

[Billy Shafer]

So basically you are getting half voltage. Which could be senser
connection faulty or voltage regulator is out. The fact that it is
producing some voltage means. That the gen section is ok.

What K Effective is talking about. Is done when you have no or
little voltage. That unit should have a field flash switch on it.
Just engage it until voltage comes up.

It would be a good idea to check all the connections. They can get
loose over time.

1-903-536-2816

 

[jaoneill]

(quoted from post at 13:11:02 12/13/21) So basically you are getting half voltage. Which could be senser connection faulty or voltage regulator is out. The fact that it is producing some voltage means. That the gen section is ok.

More pics from left to right and back side of front panel

 

[Billy Shafer]

Well my system won't let me in this morning. But the board in the
corner by A2 is the regulator board. Check it for hot spots.

I may be making a hot spot down here. Never buy an H/P unit.

 

[jaoneill]

(quoted from post at 11:54:33 12/14/21) Well my system won't let me in this morning. But the board in the
corner by A2 is the regulator board. Check it for hot spots.
I may be making a hot spot down here. Never buy an H/P unit.

Just went out to check closely and confirmed what I could see when I zoomed in on the pic of the A2 board. Near the bottom of the board is a longish aluminum colored cylinder that looks as though it must have got warm, it's plastic coating is partially melted. Do you think that could be the problem?

 

[wore out]

(quoted from post at 09:21:12 12/14/21)

(quoted from post at 11:54:33 12/14/21) Well my system won't let me in this morning. But the board in the
corner by A2 is the regulator board. Check it for hot spots.
I may be making a hot spot down here. Never buy an H/P unit.

Just went out to check closely and confirmed what I could see when I zoomed in on the pic of the A2 board. Near the bottom of the board is a longish aluminum colored cylinder that looks as though it must have got warm, it's plastic coating is partially melted. Do you think that could be the problem?

Sounds like a failed electrolytic capacitor, are value and voltage markings still visible on it? (Should be an EASY fix if they are.)

 

[Billy Shafer]

That could very well be the problem. Some items do get warm. But not
hot enough to melt the coating. I will see what I can find.

 

[jaoneill]

The second pic down in my post from 8:35 last night you can see the peeled coating on that capacitor or whatever it is, it's near the bottom of the board.