Known Running MEP-803A stops making power randomly - S5 or K1?

[Waukesha]

I have had this generator for 2 years now. It’s a known runner, that I’ve run for hours at a time without issue. Unit has ~120 hours per the meter and has not been reset.

I started it up today and closed the S5 and the light didn’t illuminate. Turned my load on to find out that I didn’t have my power. I pulled out the multi meter to find that I do have 120v at the convenience outlets. M2 frequency meter registers 60hz and M1 voltage gauge registers 240v. Unit is set up for 120/240 single phase. S6&S8 are in the correct positions.

What’s random is after a few startup/shutdowns while trouble shooting, the unit produced power twice for ~8-10 minutes each pulling an~45amps @ 240v resistive load. Each time the output terminals lost power the convenience outlets, M1 & M2 all continued to register as normal.

Steps I’ve taken:
**I exercised the S6 and S8 thinking that maybe corrosion was causing the issue, no change.
**used TM 9-6115-642-24 to try and test the S5 per 2-51.1 and 2-51.2.

I have not tested the K1 as I’d like to exhaust all options before removing the top cover.

Questions:
(1) What pins on the S5 should actually have continuity while the unit is off and battery disconnected?

(2) What pins on the S5 should have continuity while holding the S5 in the closed position Withrow the unit off and battery disconnected.

(3) What pins on the S5 should have continuity while holding the S5 in the open position Withrow the unit off and battery disconnected.

Also, what is the likelihood that either my S5 or K1 randomly failed?




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[Guyfang]

I have had this generator for 2 years now. It’s a known runner, that I’ve run for hours at a time without issue. Unit has ~120 hours per the meter and has not been reset.

I started it up today and closed the S5 and the light didn’t illuminate. Turned my load on to find out that I didn’t have my power. I pulled out the multi meter to find that I do have 120v at the convenience outlets. M2 frequency meter registers 60hz and M1 voltage gauge registers 240v. Unit is set up for 120/240 single phase. S6&S8 are in the correct positions.

What’s random is after a few startup/shutdowns while trouble shooting, the unit produced power twice for ~8-10 minutes each pulling an~45amps @ 240v resistive load. Each time the output terminals lost power the convenience outlets, M1 & M2 all continued to register as normal.

Where red were you taking these mesurments? At the load terminals, or from the 120 volt outlet? When you lost power, it was of course the K1 kicking off. So when that happens, you will always still have voltage at the 120 volt outlet, and the meters will read correctly. They all get there voltage before K1.

Steps I’ve taken:
**I exercised the S6 and S8 thinking that maybe corrosion was causing the issue, no change.
**used TM 9-6115-642-24 to try and test the S5 per 2-51.1 and 2-51.2.
Don'tworry about S5. Slim chance it's a problem.

I have not tested the K1 as I’d like to exhaust all options before removing the top cover.

Questions: All these questions are answered in the -24 TM
(1) What pins on the S5 should actually have continuity while the unit is off and battery disconnected?

(2) What pins on the S5 should have continuity while holding the S5 in the closed position Withrow the unit off and battery disconnected.

(3) What pins on the S5 should have continuity while holding the S5 in the open position Withrow the unit off and battery disconnected.

Also, what is the likelihood that either my S5 or K1 randomly failed?


As i said above, S5 is probaly not the problem. K1 might be bad, but it dosnt sound like it. Something else might be telling it to open. I assume your load is attached to the load terminals, and not the 120 volt outlet?



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[Waukesha]

Thanks, Guyfang! Measurements were taken at the convenience outlet.

I understand that that there are pin tests in the -24 for the S5. As I indicated though, I’m unsure what is normal and what isn’t, given I wasn’t seeing continuity between any pins.. I’ll take another looks this morning when I look up how to remove the top cover to test the K1.

You are correct that the load is attached to the load terminals L1, L3, and ground. Ground and neutral were bonded, and ground ran to a grounding rod in the ground.

I disconnected the load and still could not get the S5 to consistently close..

The reason I zero'd in on the S5 and the K1 is that I could not consistently get the contractor to close. In the past this has never been an issue - hence the "known runner" in the title.

You say that S5 ln't the culprit and K1 likely isn't either, but rather "something else" is. Can you point me in any directions?


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[Guyfang]

It's got nothing to do with the load. Try this.

1. Push in The fault indicator reset, and hol it in.
2. Start the gen set with S1. When it comes up to rated speed an the meters read right, let S1 go. You should still have the fault reset pushed in.

3. Flip up S7, battle short switch. Let go the reset button. What happens? Do you get idiot lights?

 

[Waukesha]

Thanks Guyfang! I’ll try that in two hours when it will be 8am local, my neighbors may not appreciate it, but I’m moving .

I do know that one of my idiot lights is burned out, the overload light. It has been since I acquired the unit, I just haven’t had time to replace it. All other idiot lights work.

I should also mentioned that I've tried running the unit with the battle short turned on, and I still cannot get the contractor to close. However as mentioned I will try what you mentioned above and report back.

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[Guyfang]

The fault indicator lights are considered non repairable. So you need to get another fault indicator.

its 13:33 here.

 

[kloppk]

S5 operates as follows...

In the center position pin 2 is connected to pin 3.
This is what holds the contactor closed once it has been closed.

In the CLOSE position pin 2 is connected to pin 3 & pin 5 is connected to pin 6.
Contact closure between pin 5 & pin 6 is what causes the contactor to close.

In the OPEN position pin 2 is disconnected from pin 3.
Contact opening between pin 2 & pin 3 is what causes the contactor to open.

 

[Waukesha]

Guyfang, the first time I pressed and held the idiot light reset, started the unit with S1 and fliped the battle short, the unit operated perfectly. I was able to open and close the contractor using the S5 without issue. Did it about 10x. Battle short light was on, and contractor light worked as normal.

I shut the unit down and restarted it normally with just the S1 - contractor could not be closed using S5. Contractor light did not illuminate.

I restarted the unit holding the idiot light reset and flipping the battle short and the battle short light would not illuminate. Flipping the S5 open and closed did nothing other than cause the battle short light to illuminate every time I pressed the S5 open.

Thoughts?


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[Waukesha]

However, I just took readings at the lugs and I am getting 120v L1-ground and L3-ground and 240v L1-L3... The contactor illumination bulb (DS7) doesn't light up.

Can a lose connection in the DS7 circuit cause intermittent issues like i'm describing?


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[Waukesha]

S5 operates as follows...

In the center position pin 2 is connected to pin 3.
This is what holds the contactor closed once it has been closed.

In the CLOSE position pin 2 is connected to pin 3 & pin 5 is connected to pin 6.
Contact closure between pin 5 & pin 6 is what causes the contactor to close.

In the OPEN position pin 2 is disconnected from pin 3.
Contact opening between pin 2 & pin 3 is what causes the contactor to open.

Thank you, KlOPPK, this is very helpful!

 

[jamawieb]

Are you depending on the light above the ac interrupter switch to determine if you have power to the lugs??? Just because the light doesn't light doesn't mean its not working. The bulb holder screws on and sometimes people put them on to tight so the light wont work or it could be to loose.

So if your overload fault light is not working and your able to bypass the fault system with the battle short switch, then your problem is with the overload circuit. It could be the overload relay or the burden resisitors. Look in the TM for overload fault to diagnose problem. I bet your problem is with the overload relay or R15 resistor becasue they both flow through the lights.

 

[Guyfang]

I am in agreement with Jamaweib. Will your S5 and S7 lights, light up when you push to test them? Is they light up, look at the overload relay first. If the lights do not press to test, then start with R15. BUT get smart. Read the trouble shooting on this problem FIRST, understand what they are telling you, and THEN start troubleshooting.

The he way this circuit works, is the overload relay tells the fault indicator there is a problem, and the fault indicator turns off the K1, and if I remember right, prevents you from using the S7 to over ride the fault. In any case, you have a good place to start.

 

[Waukesha]

I'm at a loss. I hooked up my 10KW variable resistive load bank to the unit and ran it without issue for 2 hours, varying loads, turning the S5 on and off... Everything worked. The only thing I did differently than yesterday was ground the unit properly (I know....).

Jamawieb - I was not relying on the AC interrupter light, I had turned a 2.5KW load on that should have kicked on when the contractor was closed and it wasn't. Today it worked fine....

 

[Guyfang]

Test, test, test!!!! And test again! Assume nothing! Trust only what you see! Problems just don't "go away".

 

[Waukesha]

Test, test, test!!!! And test again! Assume nothing! Trust only what you see! Problems just don't "go away".

I don't disagree. Like I said, the unit worked 100% of the time until yesterday when it had the fluke.. The unit was not properly grounded yesterday... Could that cause any of these issues? That's the only thing that changed between yesterday and today and when it was known running flawlessly a few months ago (for 2 years prior)..

 

[Guyfang]

I find it hard to believe it might have something to do with it. A loose battery connection, but not ground.

 

[USAMilRet]

I'm with Guyfang on this one.

 

[DieselAddict]

Grounding had nothing to do with the problem you were experiencing. Keep looking for root cause or it will fail when you most need it.

 

[Guyfang]

Have you pulled the top panel and at least looked into the AC portion? It's only a few screws. Can't hurt.

 

[Waukesha]

I have not - I'm in the process of selling the unit. I've discounted it by $1K to account for this intermittent issue. Buyer was actually watching it run when it kicked off after 8 minutes. He picks it up tomorrow afternoon. I'm moving to TX and I'm certain this thing will not pass the HOA.

I thank you all for your quick replies and help! If for some reason my buyer backs out, I'll take the top cover off this weekend and take a peek at the AC section.