Confusing but simple tech problems

[Ex-Calif]

I think what Garry is saying is this.

The green is ground and is connected to neutral "inside" the generator. Upstream of this the generator expects say 10 amps on Black, 10 amps on white and 0 amps on green.

If it senses 10, 9 and 1 there is a ground fault and 1 amp is coming back via the green. The RV (unlike a house) isn't actually grounded to the earth.

 

[Isaac-1]

All of this talk of how GFCI works is fine and good, but does not change the fact that the voltage sense circuit connects to the output from the generator winding itself (L1 and L2, with L2 being neutral in this case) and therefore can not detect ground faults. See wiring diagram on page 111 of the KY series service manual for this revision at https://manuals.heartlandowners.org...ONAN-Microlite 4000 Service Manual Spec K.pdf

 

[DonTom]

The green is ground and is connected to neutral "inside" the generator. Upstream of this the generator expects say 10 amps on Black, 10 amps on white and 0 amps on green.

No it isn't. I just had the entire AC line removed from my generator. The white and green is grounded to the frame of the generator along with a thick black wire to the RV frame.

Perhaps that is what is causing all the confusion here, as GFI detection to the generator is impossible in my case.

However, the GFI outlets can still work, of course, as they are external to the generator. All the generator will see is the less load if one of those trip and will continue to run of course.

But here, we are talking about a ground fault to the refrigerator being detected by a mysterious method. If only the refrigerator turned off, I would say "okay, the refrigerator has ground fault protection" and think nothing of it.

But here, if there is really no external circuits back to the control board, I am seeing the impossible with my own eyes.

So my only question is where the generator is getting its command to shut down when the refrigerator is in a ground fault condition.

-Don- Auburn, CA

 

[DonTom]

and therefore can not detect ground faults.

I am glad somebody here understands I am not crazy as I see the impossible happen!

Really, the only possibility I can think of is a path back to the control board from the refrigerator. The real problem is I don't think there is one. But there has to be something detected, somehow and the generator AC lines are ruled out, as at least you and I understand.

Just a coil around the green wire closer to the refrigerator than frame is all it would take if it has a path back to the control board. That would be able to detect a few millivolts of AC where it doesn't belong. But IAC, whatever it is, it has to be external to the generator.

And then the question is why should the generator even bother to shut down under such a condition. Has no need to. It cannot have anything to do with people safety when it takes 14 seconds to get the command.

-Don- Auburn, CA

 

[Ex-Calif]

I suppose we are all talking and not understanding each other.

It's one thing to say something can't happen and wonder how it is happening. As opposed to it is happening and trying to explain why.

I am a decent sparky but not a "wizzo" - Isaac posted a link to an Onan generator manual. I don't know if this covers your unit and if I was specifically troubleshooting your unit I would start there. But apparently there are 4 wires that potentially get hooked up from the generating device.

There are several ways to wire that up. I don't know how yours is wired or what implication that has to your generator.

If I am recalling the facts right your generator is shutting down and your house is tripping a GFCI and in both cases it correlates to the fridge in the RV being plugged in. I think we agree you have a fridge problem.

Why the generator is tripping/shutting down is ultimately explainable - it's not magic - but it is shutting down.

I'll be the first to say, "I don't know why your generator is shutting down." But I'd lay money it's related to the fridge, which I'd lay money has a problem.

Don't think I can add any more to this circular argument so I'll retire here.

 

[Mark_K5LXP]

I now get, in exactly 15 seconds, every time, no exceptions, code 27 "voltage sense lost" and the generator shuts down. Code 27 means the generator sensed no AC output for one continuous second.

I think the direction I would approach this at this point is to find out why the genset is unhappy. In other words the GFI trip may just be coincidental to a separate issue with the generator or what it's sensing. It would be useful to know just what parameters need to exist to set a code 27. Is it actually "no output" at all, or a specific minimum voltage, or other set of conditions. Not sure that information would be readily available but it may provide a clue that in concert with the GFI trip may explain the operation observed.

Mark B.
Albuquerque, NM

 

[DonTom]

I think the direction I would approach this at this point is to find out why the genset is unhappy. In other words the GFI trip may just be coincidental to a separate issue with the generator or what it's sensing. It would be useful to know just what parameters need to exist to set a code 27. Is it actually "no output" at all, or a specific minimum voltage, or other set of conditions. Not sure that information would be readily available but it may provide a clue that in concert with the GFI trip may explain the operation observed.

Mark B.
Albuquerque, NM

Yes, I agree with all of that. According to the manual, code 27 means:

"Logic: No Sense Voltage (0 VAC across S1–S2) for 1 continuous second after start disconnect".

And I could see that one second just before the generator shuts down. 14 seconds for no AC output as shown on a fast neon light. Generator engine starts to shut down at 15 seconds. So the shut down command is coming in 14 seconds after the generator is started whenever the refrigerator is on AC and in a ground fault condition.

I no longer have the refrigerator ground fault condition, unfortunately, so I could not complete my experiments. I hope the problem returns someday!

I am still tempted to get that water hose!

73, -Don- AA6GA

 

[DonTom]

It's one thing to say something can't happen and wonder how it is happening.

I am not saying it cannot happen. It was happening, so that's a fact.

The only question is how it is happening--what is possible. And I already gave examples of how it is possible. Just unknown, as it has to be external to the generator AC output.

It's not important at this point, other than to satisfy my curiosity.

-Don- Auburn, CA

 

[Isaac-1]

Don, did you happen to look at the schematic on page 133 which is for the 50 and 60 Hz 100V voltage versions of the KY, not the standard 120V 60Hz RV unit, which shows the AC sense lead wiring going between chassis ground and L1, instead of L1 and L2. If yours were to be wired this way vs the page 111 schematic then a floating voltage on the chassis ground with neutral isolated from chassis ground at the same time could explain part of this, as the voltage comparison of L1 to frame ground with a hot frame due to the refrigerator would sense as an under voltage / no voltage condition. Just thinking outside the box here, you say ground and neautral were bonded at the generator junction box, did you check to make sure ground was connected right in the transfer switch (assuming you have one)

p.s. Ex-Calif, the reconnection diagrams should not apply to the RV version of the 4000 KY only to the commercial version as the RV version should be a 2 lead unit. Though Onan has been known to substitute 4 lead for 2 lead generator ends on some models in the past due to supply and demand, I have never heard of them doing it on the smaller more modern (post 1990) RV generators.

 

[DonTom]

. Just thinking outside the box here, you say ground and neautral were bonded at the generator junction box, did you check to make sure ground was connected right in the transfer switch (assuming you have one)

When I removed my generator from the motorhome to work on it, I had to disconnect all the AC wires. Black to the CB inside the generator. White, Green and thick black ground wire to RV frame grounded together on the frame of the generator. The other end of the AC line (green, white and small black wires in the AC cable) go to the outlet that I must plug the shore cable into when I use the generator. No transfer switch.

-Don- Auburn, CA

 

[Rob&Deryl]

For the purpose of a self contained rv, the frame IS ground.
As I said above, the generator (including its remote panel) only cares about protecting itself from damage.

With regard to bonding at the generator, you are confusing voltage with current. Of course, with green and white connected together, at (or near) that point, the voltage will measure the same. However, to do work, current must flow. This is alternating current, or AC.
The current flows back and forth out and back through the white and black wires. If some of that current leaks to the frame, it will get back to the generator (actually alternator but...) through the green generator wire - the wire from the inside of the unit, then to the white where it is connected to the green. Given that all wiring has some resistance, a voltage difference can be measured ( just a few milivolts or perhaps even several volts) which can indicate something is amiss, so, shut down before damage might occur.

in short, both your garage GFI and the generator are telling you that there is something wrong with the refrigerator. Before the problem, all worked.

 

[DonTom]

With regard to bonding at the generator, you are confusing voltage with current

Frame, green and white is essentially a single wire that the generator sees in reference to black. But yes, a GFI outlet can still work on its output, but that is NOT the issue here.

The black lead does not care if the current comes down the white, green or frame. It will add the same if it comes back on a single wire, two wires or all three possible paths (frame).

A 1/3 amp return on three different wires is one amp.

Same one amp if two wires when each carries 50% of the current.

Same with a single wire carrying 100% of the current.

Simple Ohm's Law says so.

Therefore, there is no difference and here I am talking current. In fact, I always was talking current as that is how GFI works, the current to green or ground is subtracted from the white and that can easily be sensed. Even if the generator goes to a GFI outlet, because only the output of the outlet has to trip. Notice when a GFI outlet trips, the full voltage is still connected to the input of the same outlet and can kill a person easily. Only the output of the outlet is switched off. IOW, the outlet is externally sensing away from the AC source. GFI is an added circuit to a regular outlet.

That is the point some here are missing.

Whatever was being detected has to be external to the generator's AC line.

GFI in an outlet can always work, even from the generator, as the GFI can the see a true difference in current between the white and black and ground. But that is added equipment, like I was trying to explain. A regular outlet will not shut down anything. AC still goes into either type of outlet, just will not come out from the GFI outlet when tripped.

Like I said, if the refrigerator turned off when on generator I would think nothing of it, if the generator continued to run. But it is somehow turns off the generator when the load path is exactly the same path as a GFI condition.

The only way that is possible is via the control board sensing something is wrong somewhere. It cannot be the AC wires of the generator.

BTW, I thought of another experiment I could have made while I was on shore power without GFI.

I should have ran the generator into an open outlet and see if it still shuts down in 15 seconds.

However, since then the refrigerator is then on shore power and working normally, it probably won't shut down anyway, but if it did, it would prove how it works.

-Don- Auburn, CA

 

[JayArr]

You have confirmed that the AC output of the genny goes to zero at 14 seconds and one second later the genny faults out with code 27. I don't think the genny is shutting itself off.

Does the fridge have any circuit in it that delays startup for 14 seconds after AC is received? If you put a meter on the heater element now (since it's working) does it remain at zero for a little while after AC is applied before the control circuit starts it up?

Maybe this was simply a dead short on the line that wasn't put there until the fridge control board activated some relay at the 14 second mark. At this point when a short is thrown across the line the genny would wait one second then shut off.

When connected to shore power is your white and frame separated? (I think it should be because it would be bonded at the fuse box of the house and it shouldn't be bonded twice.) I know it is bonded in the genny but you physically disconnect the plug from it to plug into shore power so that bond inside the genny isn't active on the RV if the plug isn't in the genny, correct?

If the fridge shorted to ground while connected to a house GFIC the return path from the fridge to the GFCI outlet would have separate white and green paths and it would trip the outlet would it not?

 

[CharlesinGA]

Unrelated but, check your drain tube on the fridge condensate drain. My had a white corrugated tube that was broken and when you touched it, it crumbled. I finally obtained a new tube (new part number and black in color) and I think it is a softer plastic that won't crumble when it gets old. I did not try to use Tygon or other tube as it was right on a refrigerant line and It just didn't look like it would work. Instead of draining outside (I have bug screens on the vent) I installed a small catch tray with double sided sticky 3M tape and routed the tube into it with the anti bug plug in the end (has small holes in it). This is similar to how a Norcold works. I think I have the same model fridge as you.

Charles

 

[DonTom]

I don't think the genny is shutting itself off.

I think any of the codes turn off the generator. High voltage, low voltage, high frequency, low frequency --any of them shut down the genny, including code 27. So it's the code shutting down the generator. The generator shutting down by an engine fault will also set a code, Code 36, such as if the fuel pump craps out. Code 36 means "GENSET STOPPED WITOUT FAULT CONDITION."

A dead short on the AC line should trip the circuit breaker inside the generator. It doesn't trip. Perhaps also would set a low frequency and low voltage alarm before the CB trips.

If the fridge shorted to ground while connected to a house GFIC the return path from the fridge to the GFCI outlet would have separate white and green paths and it would trip the outlet would it not?

Yes, if there is more than a few ma of current on the green or ground it will be detected as a loss at the white wire by the same amount and trip the GFI. If the fridge is pugged into an outlet on the generator, it would be exactly the same, of course. But then the generator should continue to run, but not the fridge, just as there is still AC behind a tripped GFI outlet. GFI is an additional circuit to the AC source and that will only shut down the load, not the AC source.

But that is an interesting question that perhaps the refrigerator takes 14 seconds to turn on or to do something else in 14 seconds. That could give a clue of what is being detected and sent back to the genny control board somehow. Other than an engine malfunction, I think only the control board can shut down the generator--and that is where all the codes come from as well.

Yeah, I will do that experiment to see if there is a change of current to the refrigerator at 14 seconds when turned on to AC from when off. I just now found my Model P4400.01 KW meter. I have not used it in years. Your question made me just now look for it.

Great idea, thanks. I will let you know the results tomorrow, right after I check it. I will be looking for anything that changes in 14 seconds in the AC draw power after first being turned on.

However, the refrigerator would trip instantly when I was connected to my garage GFI outlet. Less than a second for it to trip.

But still, something happens in 14 seconds. And Code 27 only mentions the single second after those 14 seconds. Great idea. Thanks.

-Don- Auburn, CA

 

[DonTom]

Unrelated but, check your drain tube on the fridge condensate drain. My had a white corrugated tube that was broken and when you touched it, it crumbled. I finally obtained a new tube (new part number and black in color) and I think it is a softer plastic that won't crumble when it gets old. I did not try to use Tygon or other tube as it was right on a refrigerant line and It just didn't look like it would work. Instead of draining outside (I have bug screens on the vent) I installed a small catch tray with double sided sticky 3M tape and routed the tube into it with the anti bug plug in the end (has small holes in it). This is similar to how a Norcold works. I think I have the same model fridge as you.

Thanks, will do. I don't think I have even looked in there for more than a year.

-Don- Auburn, CA

 

[DonTom]

I did the experiment today, nothing changes at 14 seconds, but I found several interesting facts.

When only the refrigerator is running (all other CBs are switched off), my total RV draw is 0.01 amp @ 120 VAC. That is only 1.2 watts. Seems way too low to get much heat! How much current should the 120 VAC element draw? I left it on for more than an hour, it never tried to switch to propane so that isn't the issue. I have my propane tank off and there is no check light indication after more than an hour of operation.

My meter also measures VA, which is 1.2 VA or a waste of an otherwise possible 0.1 watts, not that much wasted energy. Perhaps the inductance in the heater element? Is it a coil? I have never looked at it.

I also checked for changes for DC. I wired in the SmartShunt. Still nothing changed at 14 seconds.

Another surprise is the refrigerator plugs into an outlet that doesn't seem to be GFI protected. I deliberately tripped all the other GFIs in the RV and the refrigerator outlet still worked normally, so I know the refrigerator is not using the GFI from another outlet.

But I say "seem" above because it's a very weird looking AC outlet and I couldn't find my GFI tester to do a GFI test on it to see what happens. But all the other outlets in my RV are GFI protected in one way or another. Why would the refrigerator be different?

I will get a real GFI tester in the next couple of days just to be 100% certain it has no GFI. If not, should I consider installing one there?

Of course, if it does or doesn't have GFI, all this has nothing to do with why my generator was shutting off anyway.

But it sure looks like there is no GFI in that one outlet. But it's a rather weird AC outlet I don't recall seeing anywhere else before. Here is a photo of it below.

-Don- Auburn, CA

 

[Old_Crow]

That outlet looks the same as the one that the converter on my coach plugs in to. I just figured it was purpose built for a circuit designed for only one load. There is also a standard outlet in the same storage compartment, but it's on a different breaker.
The outlet in my fridge compartment is a standard 2 gang outlet, probably because the original fridge had an ice maker.

 

[DonTom]

That outlet looks the same as the one that the converter on my coach plugs in to.

Does it have GFI?

BTW, I had my RV on AC all night, refrigerator left on. It is NOT getting cold! Perhaps my 120 VAC heating element broke? Perhaps related to my ground fault issue as well as my generator dying?

That will explain the 1.2 watt heater element!

In my last message above, I meant 1.3 Volt-Amps / 1.2 watts. I cannot now edit it.

BTW, how long can it take for the freezer to get cold when started from 120 VAC? I assume overnight should have been long enough to show at least some change. Looks normal, (other than the very low current draw) just ain't working.

-Don- Auburn, CA

 

[DonTom]

I just did some testing on my refrigerator and it looks like I found a problem with why it isn't working on AC and is most likely related to my generator shut down.

I removed J7 and J8 from the refrigerator control board and made some resistance checks. J7 and J8 goes to the 120 VAC heater element. I don't think these readings can be normal:

18KΩ (18,000 ohms) across the 120 VAC heater element. One side shows zero ohms to ground. Can somebody here tell me what I should be reading? I would expect a few ohms and no short to ground at the element, far from what I am seeing.

-Don- Auburn, CA