Natural Gas Whole House Generator not Transferring Power and Shutting Down

There are a number of safety features on generators that prevent harm to the unit or people in the area. Maybe this will help.

https://www.cleverhandymen.com/why-does-my-generator-keep-shutting-off/

My WAG is you have a fuel problem. (You did not mention anything about fuel. So I guess fuel.)

This need not be a lack of fuel in the fuel tank. You may have a sediment problem in the fuel filter or even too much water in the fuel water trap.

Wait a minute, is this the same Onan RS12000 NG generator you had trouble with seven years ago?

I think that either your last repair job has failed again or whomever you have performing maintenance on this is doing a bad job.

He tells us Natural Gas fuel.

Natural gas... hmmnm

Is, perhaps... this is a long shot... is the NG supply at pressure and volume when you lose shore power?

It should be, for a while anyway. In the perfect world it would be for several days.

I read thru the thread redfred linked. Can you give us a brief rundown of upgrades, repairs, operating temperament of the machine since that discussion?

I have done annual tune ups (plugs, oil, air/oil filters), used it as needed during power outages (but I had to started it manually) without any other issues.

I recently did a check of electrical connections and noticed one that was not fully connected to the controller on the generator. When I lost power this time, the generator started fully on its own which it hadn't done for 7+ years so I was happy to see that, but then when the transfer switch tried to transfer the load to the generator, the generator shut down.

Not knowing where you are is possible that condensate freezing in the gas line is limiting the gas volume?

Hi Redfred. Yes it is the same generator but I have never had this problem before. It ran fine after my tune up in the fall (changed plugs, oil, air filter) and ran it for 20 mins after to ensure it was ready to go.

I have never had a situation where it wouldn't carry the basic load of the house...in other words, just the 15 and 20 amp breakers. (No microwave, ovens, dryers, etc).

I am going to simulate a power outage this week and see if it will transfer over with no load. If it transfers successfully, I am going to turn on one breaker at a time to see what happens.

It sounds like the generator was overloaded, should not be run over 80% load, that's 9600 watts, one 10kw heat strip....after you shut the breakers off it should have restarted, however I think it takes 5 min for the system to reset...check your blinking codes, and you have to wait for it to stop blinking before restarting...

https://www.generatorjoe.net/html%2Fonan%2FCURE-011T001ops.pdf

Might be something there.

I have a 10kW gen for my house, this intended to run the primary appliances at 100%, and that is about all. Primary watt suckers are the fridge, two chest freezers, elec water heater, gas furnace blower motor, and a water pump. If their individual cycles all coincide, I will usually lose the genny.

Electric kettle (900 watt I think), clothes wash and dry, microwave (big one, 1500), dishwasher, toaster oven (1500 watt), three fans at, I dunno, 200 or 300 each, toaster, rice cooker, can opener sucks a lot of juice... All of this sort of appliance can only be used if something else is locked out.

Air conditioner use is limited to extreme circumstances.

I knew all this when the generator equipment was selected.

Perhaps our OP was promised the 12kW was plenty to operate his entire 4 BR home at 100%?

Hi Doorman. Thanks for the comments. I know that my genny will not cover the whole house completely. We cannot use the ovens (standard or micro), dryer, etc but it has always handled the fridges, freezer and general items (lighting, TV, internet etc). This is the first time it wouldn't take just those loads.

Thanks Solar Eagle. Good to know. I am going to simulate an outage this week and turn breakers on 1 at a time to see just how much load it can carry.

...as Doorman said, it's not the breakers, it's what's on at the time that counts... most generators have a surge rating that lasts for a short time...the best way to check is to monitor the amperage....amps times volts = watts....you're looking at about a 40 amp max load...ideally

Thank you for the feedback. Simple math like that (Amps X Volts = Watts) makes sense to me and wanting to stay under 9,600 Watts (80% of 12,000) also makes sense. It's the figuring out how many amps and volts I am asking the generator to cover when I transfer the load that I am unclear on.

What device can give me that information and where would I use it? At the generator? At the transfer switch?

Prolly the best way to audit your consumption is like this:

I just had a look, my electric kettle mentioned in #7 draws (consumes) 1200 Watts, not the 900 stated. Every appliance, large or small, has a nameplate with its general information, power consumption is listed there.

List out everything with a plug, and everything that is hardwired. For this exercise I don’t include the woodshop tools, things like that. Vacuum cleaner is, however, on my list.

LIST THEM ALL OUT! Make yourself a chart, maybe a spreadsheet, items and Watts. For ceiling fixtures, I use all LED light, so I just lump them together and call it 200 Watts. Your mileage may vary.

Now, you can see just what can be operated at the same time. You have 10,000 Watts or so, just add up the loads. This is sort of the tricky part, called Duty Cycle. The kettle draws 1,200 Watts... but not all the time. Neither does the 1,800 watt water pump nor the 5,000 watt water heater. But the independent automatic operation of many primary appliances might coincide, this is where my overloads come from.

In my generator procedure I do not turn on the water heater (deemed my least critical and biggest wattsucker) on startup. If power was lost in the middle of a dishwasher cycle, I can finish the cycle with whatever hot water remains.

Yes, a power audit of the household electrical items is a good, safe place to start. Paying close attention to those items that automatically operate (heat, refrigerators, well pumps, etc.), those which are desired during a power loss but manually switched (range, lights, microwave, etc.) and items not really needed during a power outage (shop tools, washing machine, etc.).

If one must cook food with electric power then the microwave will usually require the least amount of power.

It's easy to use a clamp meter, you just set the meter on the proper scale and clamp it around a wire, the meter will tell you haw many amps are being drawn in that wire....so you can check it at the main wires either at the generator or at the meter probably easier to get to the wires at the meter, now if you have 230v you check either wire, and if you have 120v you check the hot wire, so if your running both you check both wires and amps times volts = watts...

If you don't have a clamp on ammeter and need to buy one think about an AC/DC one, more costly but you will be surprised how often you need to measure a battery charge current or a load draw, I know I use mine all the time.

If you just have a multimeter buy a clamp on CT head and connect to the appropriate terminats and measure the current.

I agree with Solar Eagle-

All of the heavy loads like the heat pump, water heater, air conditioner, electric stove, etc. must all be turned off before starting the generator.

Each Load can be added back to the rated capacity after about three minutes once the generator has stabilized…

It may not be the transfer, but with the engine sensors

you checked the oil levels, good.

some other items.

• oil level sensor failure.
• coolant level
• coolant level sensor failure.
• and of course the fuel supply issues…

We have a Onan as a backup power source on the farm, but it’s powered differently.

What is a good idea, and what we try to do on the farm. we’ll test it once a year. It’s a pain in the butt, but it’s there when you need it, which is the reason it has to be tested.

Thanks Phoenix911. I wondered if it was a sensor which is why I thought oil pressure first. I drained a little because the dipstick was showing it slightly above the top line. That didn't fix the problem though.

It is air cooled so no coolant level sensors. Fuel could be an issue, but because it is NG fed from the street it would come down to am I getting enough of a flow rate to the generator. I doubt this only because it was shutting off at the exact same time each time which seemed like a sensor issue.

When it shuts down by itself...

Does the engine sound like it’s fuel starving, or more like it is switched off, or does it lug down, like running your mower thru tall wet grass.

When you hear thundering hooves, think horses, not zebras. That is to say, eliminate the more likely sources before looking for complicated and wonderous problems.

The dipstick oil level may only appear to be higher than normal when the oil is still hot..

UPDATE

Supposed to have winds tonight and possible outages.

This morning I went to the transfer switch and pressed the Generator Start/Stop button. The generator fired up. I let it run for 5 mins.

Then I pressed the Transfer button. It transferred successfully and I left it transferred for 5 mins. I transferred it back to Utility and then tested the whole thing again with the same result.

I did go inside while on Transfer and tried to overload the generator. It was ok with the Microwave, but the Dryer killed it. I assume the electric oven would have done the same.

This tells me its ready to go and whatever the issue was the other night has been resolved. The only difference in load from this morning compared to the other night were my old school C9 Christmas lights. If the power goes out tonight and I have the same experience, I will turn them off and see if that's what was pushing the load over the top.

You still were not able to establish what caused your generator to purposely quit on its own since you failed to duplicate the exact scenario..

You should have at least measured and monitored the actual current being drawn from the generator during your test.. which can serve as your reference operating point and as a threshold for the generator failure..

Yes that is correct which is why I was hoping for a power outage last night. It didn't happen so I may need to simulate it on my own in the evening sometime this week. The only thing that was on when it wouldn't carry the load that wasn't on when I was testing it with load yesterday morning are my Christmas lights. They are old school C9 lights and I have a couple hundred of them...maybe they put me over the load limit the other night????

So how many old school C9 lights do you have?

The above chart is from here. That's the nominal wattage for each bulb on a lighting string. So with just one couple of hundred bulbs (200+) this adds up to 1.4~2.0 kW of power your generator's 12 kW produces. This holiday display is all by itself consuming over 10% of your backup capability.

I'd figure out how to take these lamps off of your backup circuits. I'm all for being festive but when the rest of your neighborhood is in darkness do you really want to flaunt your home?

RedFred - you might be onto something here and no I don't want to flaunt my home in an outage. I hate even running the genny at night but I wear a CPAP when I sleep that needs power to run so...

I will kick the lights off for the next night time text and then turn them on to see if it kills the generator.

Thanks for the input.

Yes Mr. Fred has a good point, which is why if you can measure the actual power being drawn during or while your gen is running..

Whatever value measured will be your basis to compare what the generator actually is producing at every moment..

Whether it still produces the rated capacity or not is another topic for discussions...

What kind of heat do you have? If you have gas available I would think you have a gas furnace, and clothes dryer, and stove/oven, and water heater as these are the big power users and gas is cheaper than electric, at least it used to be...also you can still cook when the power is off, and have hot water...

Those modern appliances you mention all need power to run, gas only provides the heat.

If you have an old water heater with a pilot flame, you get hot water for as long as the water pressure keeps up. Furnace, no power = no blower. Dryer, no power = no drum motor.

I have a gas range, I think the surface burners can be lit with a match - I know the oven won’t operate without 120vac.

The heat is the bulk of the energy demand....You could run one at a time no problem...

Agree, probably all major appliances listed no problem... if the genny is operating.

As long as I keep the electric water heater off, I can run the remainder of my house (gotta watch those portables - microwave, toaster oven, kettle, waffle iron, etc) more or less seamlessly. If OP is operating a gas water heater (hands off the A/C) his available 10kW +/- should be enough to do similarly.

In #23 he tells us electric stove and clothes dryer. No word on hot water. Still waiting to hear about the electric pool heater. Stove/oven is going to be a big power draw.

Wow! I just checked the spec on the Onan RS12000. Says 191 ft³/hr of NG at full load. Let’s hope the power gets restored pretty soon.

[edit] Genset spec I found is prolly current production, unknown if this is applicable to 20 year old machine. Geez, subject genset might even be worse!

1 one-million British Thermal Unit to cubic feet of natural gas = 1,000.00 cu ft N.G. ( cost $14.71) ~$3 an hour at full load, though more likely to average well below this, maybe $1 an hour....You definitely would need an on/off schedule...maybe run for 30 min then off for 2 hrs...

Doorman, I am curious about your comment of "Says 191 ft³/hr of NG at full load". Is that good or bad?

Probably about the same as diesel....neither good nor bad ...it's all expensive...

As SE says, not a bad thing, just on the expensive side to operate, fuel consumption dollars wise.

Reviewing the Oman literature I found, it tells me the genset is rated at 12kW when run on LPG, derated to about 10kW with NG. As I stated, the spec I found online is likely not for the genny in your back yard, but this leads me to suspect yours is similar. This means you may actually have 10kW surge/8kW sustained.

Here is what I found: https://northshorepowerelectric.com/wp-content/uploads/2014/06/RS-12000.pdf

Somebody might have a look, make sure I am reading this correctly.

With the revelation from redfred, starting to look like the machine is simply overloaded.

It should have the electrical rating on the data plate...it seems you're probably right...I put this at 10kw on NG and 11kw with LPG

gas furnace, gas stove but electric ovens, dryer etc. Yes stove and fireplaces work without power.

Have you checked your gas regulator for proper operation,old age can stick things up a bit.

Also gas dirt filters.

Try turning off your inside main breaker the next time it fails.This will eliminate all loads.If it still fails after a few seconds,the problem is with the gen set.

All NG and LP motors have a demand regulator that responds accordingly to the load,a sort of throttle,to compensate for varying loads.It is possible that it is malfunctioning and not responding to loads.Perhaps the regulator is sticking or dirty internally.There are some very small orifices in the regulator that do not require much debris to clog.

Power meters are available in hard wired or clamp on.

Google shows plenty of them.Your choice.

The main concern I have with MG sets is frequency regulation,which will affect the life of motors,especially capacitive run motors,like heat pump compressors.

The run capacitors fail a lot after being run on generators,followed by fan and compressor if run for long periods.Sometimes they will fail quickly ,but others within a short time period.

I suggest not running heat pumps of split systems with MG set,no matter the capacity of the generator unless the frequency is precisely controlled under varying loads.

This is interesting. Hadn’t really considered the frequency as a potential motor trouble.

I run LPG, the gen has onboard digital meter that displays frequency. I have checked this displayed value against a handheld meter and they agree, so I believe the meter. Mark II eyeball shows 60.0 Hz to 60.2 Hz as loads are added or dropped. This seems acceptable, does the forum have another opinion?

The frequency is of course controlled by the engine speed which is at 3600 rpm for this model I believe, and the motor speed is controlled by the governor and/or carburetor...this is something to check as regular maintenance and adjust if needed....

Sounds like you have an excellently regulated generator.Ultimately,the linkage to the governor on the engine will wear,and need adjusting,but it sounds like yours is working fine,especially if it has frequency feedback for engine speed control.This can compensate fro some wear in governor linkages.

Yes, also holds very solid 120/240vac until it bogs down at full/over load.

From your comment I worried a bit about the fridge and freezers.

They seem to be a little more forgiving,due to lower hp requirements,but the freq does bear watching and keeping load within the capabilities of the genset.

For reference and comparison, here is the motor tag from my Cummins Onan RS12000

9kw rating then 7200 watts max load....30 amps max continuous load...

I’m anticipating that you don’t live in Cheyenne WY, or another city with elevation 6- odd thousand feet above sea level.

Elevation also derates the genset, yours is listed as 3.5% per 1,000 ft elevation. So, in Cheyenne you would take the 9kW less 6 X 3.5%, leaves about 7,200 Watts surge...

Then less about 20% for sustained load.

Doorman - no, I am in the PNW Seattle, WA area. About 500 feet above sea level.

Ah, very nice place. I have relatives (that I really should go and visit again soon) in Port Angeles, Sequim area.

Elevation derating isn’t any trouble for you.

Do you have any more test results to share with us?

Somebody should design a supercharger system for these generators for as much use as they get...

It sounds as though it is being starved of fuel.

Some possibilities:

• Try starting and running it on a much-reduced load. It may be that the demands being placed on it are too great for it to sustain.
• Look at the fuel delivery lines. Eliminate all kinks in pipes, all partly-closed valves, and make sure that any fuel filter is not blocked.

A phone call to the manufacturer is always worthwhile. Do let the forum know how it went.

Thanks PWSlack. I think I have zeroed in on the issue. I was able to run and transfer the house load over to the generator the morning after I had this issue. The only thing that wasn't on in the morning that WAS on the previous nights were my 122 C9 Christmas lights drawing 7 watts each for 854 watts of constant power.

it is my belief that those lights were the issue that was causing my generator to shut down.

I now have a better list of my load from walking around the house and getting actual wattage calculations. I will ensure my christmas lights are off AND I switch to LED for next Christmas.

Thanks to everyone for the help, insight, suggestions and knowledge. You guys are a cool group.

https://www.coloradostandby.com/cummins-rs13a-13kw-natural-gas-and-propane-generator-c13n6h

Yep.

My only test instruments are digital and analog VOM. I find some handheld combo VOM/Oscilloscope (similar to that used in the genny test video) available for less than a hunnerd bucks. I think I am gonna pop for one. I’d like to verify that my emergency generating equipment isn’t making dirty power. I realize the ‘scope function is prolly not going to very accurate, but it should at least give me a decent general idea of waveform.