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Whole house generator question

R

rlk

Bronze Member
I have a 16kw Generac Whole House generator installed, along with the associated transfer switch.

The last time the utility power failed, the generator came on as it should have. While running on the generator, we noticed 2 ceiling fans were humming, and the UPS systems for our PCs started clicking. As soon as the utility power came back, the ceiling fans stopped humming and the UPS systems stopped clicking. The hum from the ceiling fans was quite loud.

I called a repair company that specializes in Generac generators. A young kid who had just finished generator school came out and said a new circuit board was needed. He replaced the board and that did not fix the problem. He took that board back out and said a different board was bad. He did not have one with him, so said he would come back the next day with the needed circuit board.

A week later (today) he shows up with the new board. This new board did not resolve the problem either.

He tested the hertz, volts, and amps from the generator and everything was withing specs. Not knowing what else to do, he called a more experienced tech. They talked on the phone for about a half hour, and finally gave up. They have no idea what causes the ceiling fans to hum and the UPS units to click. They did not appear to want to work on the problem any more.

Do any of you have any thoughts what the problem could be?

Thanks, Bob
 
Sounds like very low voltage on one leg of your generator output. One side may be drawing a lot more than the other one in your panel as well depending on how it was wired into. Balanced loads are real important with generators.
 
Did he also do his checks at the fan and at the UPS, or at least on the breaker panel bus?
Was the transfer switch humming too? With everything dead, I would also retorque all the bolted connections from that generator to the bus.
 
Must be a small house, might re-check the load your putting on it. No way that would keep my home going (even minus the garage) !
 
16 k should keep most houses running less than a/c i would have the electrican looki the instalation over sounds like a floating nutural or a weak leg could just be a conection issue you should be seeing 120 ac between hot legs and nutural and 240 between hots under load and your frequency should be 60 cylcles not with in specs that is what the set should be putting out i can buy off on 59 to 61 hz voltage should be 120 and 240
 
waybomb said:
Did he also do his checks at the fan and at the UPS, or at least on the breaker panel bus?
Was the transfer switch humming too? With everything dead, I would also retorque all the bolted connections from that generator to the bus.
Click to expand...

Waybomb, he checked the electrical receptacles the UPS units are plugged into. All checked out o.k. (volts, amps, hertz).

At the transfer switch he checked the output of the generator. At each distribution panel in the house the output of all breakers were checked. Again, everything was within specs.

Don't know if the transfer switch was humming. Doubt if it could be heard it because it is right beside the generator.

He did not re-torque anything, but appeared to check for loose connections with a pair of needle nose pliers. I could ask my neighbor (a licensed electrician) to pull the meter then re-torque everything. At this point that's all I can come up with.

Bob
 
Big Dog said:
Must be a small house, might re-check the load your putting on it. No way that would keep my home going (even minus the garage) !
Click to expand...

With all gas appliances, 16kw is large enough for us. The generator was installed in 2006 and has performed well through several power outages. The ceiling fan humming and the clicking UPS units just started during the last power failure about a month ago.

Bob
 
Call up the history log files on your UPS's -- they may be a source of info.

Square/sine waves also may be the difference
 
Yup with gas appliances 16,000 watts would run most any house quite nicely!!

Check that ground....

Regards, Kirk
 
JEV said:
Did anyone check the earth grounding of the frame?
Click to expand...

I checked this today. The ground wire is securely fastened to the generator, and where the ground wire fastens to the grounding rod for the house there is a secure connection. Is there anything else I could check regarding grounding?

Thanks, Bob
 
Have to wonder if they installed just any old ground rod, or they installed the proper length one for the earth around your place.

I don't know how to figure what length and diameter rod you'd need, but I do know it matters.
 
a ground rod should be copper coated and driven 8 feet into the ground most electricians will have the gear to check your earh ground some soils won't ground as well as others so a good test is in order if your ground dries up or freezes up you won't get as good of a ground we some times had to mix up a salt brine and pour it around ground rodds
 
A new ground rod was not installed when the generator was installed. The generator is connected to the grounding rod that was installed when the house was built in 1972.

As of now, the only other suggestion I have is to ask my neighbor, a licensed electrician, to remove the meter and torque all the connections from the generator, the main panel, and the two distribution panels.

Thanks for all the suggestions so far. Bob

Bob
 
I'd get a killawatt meter and put it on the line side of your ups for starters it will tell you a lot.

314Xry08unL._SL500_AA300_.jpg


[ame="http://www.amazon.com/Arbor-Scientific-P4400-Kill-Meter/dp/B001JHGY2Q"]Amazon.com: Kill a Watt Meter: Everything Else[/ame]

for the non electrician type I suggest them.

tom
 
A neighbor electrician. That's good. Once everything is tight, and ground checked, I'd ask the electrician if he can borrow an instrument like a Dranetz PX5. This won't tell you what is wrong with the genset, but it will tell if there is something wrong with the power quality it delivers.
 
rlk said:
I checked this today. The ground wire is securely fastened to the generator, and where the ground wire fastens to the grounding rod for the house there is a secure connection. Is there anything else I could check regarding grounding?

Thanks, Bob
Click to expand...
I had similar problems with power quality with my portable genset until I drove a separate ground rod JUST for the genset. My problems cleared up with a dedicated ground rod driven to 8', but it's just a 6500 W unit and not as large as yours. Hope your neighbor is able to isolate the problem.
 
I may be about a mile off target, but humming motors sounds to me like square
wave power, not true sine wave. Is it possible those "circuit boards" are clipping the
sine wave??? As in an over voltage situation. So the top and bottom get clipped
turning it into a square wave.
I would find someone with an oscilloscope or one of those new test meters with
o'scope function.

Ralph
 
dds said:
16 k should keep most houses running less than a/c i would have the electrican looki the instalation over sounds like a floating nutural or a weak leg could just be a conection issue you should be seeing 120 ac between hot legs and nutural and 240 between hots under load and your frequency should be 60 cylcles not with in specs that is what the set should be putting out i can buy off on 59 to 61 hz voltage should be 120 and 240
Click to expand...

The floating ground on portable generators destroy all items in a house with transformers in their power source than you can imagine. Transformers are heating up while they are humming and getting ready to turn loose of that magic smoke that can only be installed at the factory.

Like Big Dog said, that isn't even close to being enough power to run my house. I "limped along" with 15k of generator power for years only running vital electrical items. If I tried to hook 15k up to my whole house, the generator would just shut off immediately and possibly destroy some items with transformers just for fun. I had 3 different electrical companies that specialize in generator installation, not just any electrician, come out and give me estimates on what size I need and what price. All three told me that I needed 45k minimum and recommended 65,000kW. I ended up going with a Yanmar diesel powered 65,000kW unit.

Unless I'm running two or three A/C units, I really don't burn much more fuel than with the little generators running at max load. That's beside the fact that something will last much longer when it's not running at it's maximum output 24/7. Sure, I could have had a 2nd panel for my generator that just ran vital outlets, but that's not how I want to live. We've had outages last weeks. No more running around with flashlights or candles for me and no more worrying about low voltage destroying my electronics. In many cases low voltage is worse than some spikes.
 
rlk said:
With all gas appliances, 16kw is large enough for us. The generator was installed in 2006 and has performed well through several power outages. The ceiling fan humming and the clicking UPS units just started during the last power failure about a month ago.

Bob
Click to expand...

I don't know the size of your home nor how many circuits you have attached, so all I can do is guess. I'd first do as JEV suggested and be damn sure everything is properly grounded. If it is, you are likely experiencing a generator dying because it can't carry the load it's been carrying. The electricians I had out install about half of their generators to trailer homes way out in the boonies where they lose power frequently. They tell me 12k to 15k air cooled units are generally what they hook up for a trailer home.
 
I ended up contacting Generac since the local repair people gave up on finding the problem. Generac recommended a company in Greensboro that I talked to this morning. Told the lady that answered the phone that I needed a sharp individual and not someone who has just graduated generator school. She laughed and said she had just the person to send to me. At the end of the conversation I asked her again if the person she was sending was well versed in all types of generator voltage/hertz/amperage problems. She assured me he was.

He is booked solid until Oct 13. Hopefully we won't have any more storms before then.

Thanks for everyone's suggestions.

Bob
 
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rlk said:
I ended up contacting Generac since the local repair people gave up on finding the problem. Generac recommended a company in Greensboro that I talked to this morning. Told the lady that answered the phone that I needed a sharp individual and not someone who has just graduated generator school. She laughed and said she had just the person to send to me. At the end of the conversation I asked her again if the person she was sending was well versed in all types of generator voltage/hertz/amperage problems. She assured me he was.

He is booked solid until Oct 13. Hopefully we won't have any more storms before then.

Thanks for everyone's suggestions.

Bob
Click to expand...

You did well Bob. Just because someone is an electrician doesn't mean they know squat about generators. Making sure the guy coming to look at your issue is very well versed in generators is the best route for you IMHO. Good luck!
 
The only experience I've had personally with generators are those we had after Andrew which for the most part are portable Honda generators. Now my father built a house, a 4 bedroom 3 bath, living room, family room, large kitchen, formal dinning room and an in door Olympic swimming pool in the mid 70's. The pool was heated even though the house was in south Miami. At any rate he had a full house generator installed that would kick in the first flicker of the power company and run everything but the heater in the pool. Now brand, make type etc I really don't know but the house had power all the way through Andrew. I was their right after and before the power lines where fixed and would have never know the power was out as every appliance in the house ran fine including the refrigerator, freezer and TV sets. I might add it was rather large but in spite of that was also pretty quite when running. Really couldn't hear it in the house over the normal talking or TV.
 
waybomb said:
And the prognosis is?
Click to expand...

The repair guy (Robert) was here 3 hours. He checked the generator, the electrical receptacles in the house, the distribution panels in the house, the main electrical panel immediately after the power company's meter, the grounding for the generator, and the transfer switch.

Everywhere he checked, the volts, amps & hertz were perfect. I was particularly concerned with my AC units, the refrigerator and the freezer. He assured me the electrical service to those units, and to the rest of the house, are as they should be when running on the generator.

He did made some minor adjustments to the generator, but the ceiling fans continued to hum and the UPS units kept clicking.

Prior to him coming, I talked to several electricians, some familiar with generators, and some not. Most all agreed that small UPS units do not like generators and will do funny things. Based on this and the fact we have very old UPS units, I did not expect our units to stop clicking.

Robert was not able to debug the UPS problem. Our units are so old that they don't have many diagnostic lights on them, and we don't have the manuals for them. Until we upgrade our UPS units, we'll just have to turn off the UPS units while on generator power.

Lastly, he replaced the speed control switch for the ceiling fans with a toggle switch. That stopped the humming in the ceiling fans. Apparently the speed control switch did not like the generator power either. Robert could not explain why. The two ceiling fans that were humming both ran through the same speed control device. All the other ceiling fans in the house have their own speed control and they do not hum.

Bottom line:

  • I'm satisfied the generator is running as it should.
  • The ceiling fan problem is resolved.
  • The UPS units are still a concern. I plan to replace one and see if it handles generator power better. If it does, then I'll replace the others.
  • The generator is sized correctly for the amount of devices we need it to run in the event of an outage.
Bob
 
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