VNV1967
Have an older Generac 10KW with about 80 hours.Today power went out and Genny started and ran ok but Line voltage was at about 113 Volts AC. Feq held steady at 60 Hz. But voltage fluctuated about 2-5 volts up and down.  

Lights had a slight flicker inside the house. Genny runs every week on exercise. Been a while since last full run on power outage. No problems. New Battery and oil is good (Mobile 1) 

This time to day it started the above. After a while it did kind slow down as far as flickering.  Was thinking maybe it is the brushes on the generator being oxidized. Ran for about 1 hour before power came back and she shut down. 

Any ideas??? Thanks in advance for your help..
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78buckshot
It would be good to check the resistance of the rotor/brush/harness assembly, that could tell us if you need to clean the slip rings on the rotor. Without model and serial number we can't tell what type of voltage regulator is in your machine but that would be the next place to investigate.
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Brian Baughman
Inductive lighting, like LED or fluorescent lights will flicker on generator power.  The electronics in LED's are extremely sensitive to voltage and frequency deviations, which are common during normal generator use.  Normal voltage and frequency ranges while on generator power can be between 115-125V and 58-62 Hz as the load profile on the generator changes.  
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VNV1967
Thanks Guys for the reply...The Model Number is 005871 ..or 5871. Also the flickering is also on  incandescent 100 watt light bulbs in and around the house.  The Genny does exercise each week for 12 min. So...I would think the slip rings would be ok. How ever that was also one of my thoughts. 

I know how to get to the rear fan on the genny, but how hard is it to get to the slip rings and brushes? and also ...while there, should I replace the brushes due to the low hours? 

Your thoughts..??

 
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VNV1967
78buckshot wrote:
It would be good to check the resistance of the rotor/brush/harness assembly, that could tell us if you need to clean the slip rings on the rotor. Without model and serial number we can't tell what type of voltage regulator is in your machine but that would be the next place to investigate.




Thanks Buckshot, I would think I would need some direction in how and exactly where to check. I have the proper electronic equipment here as I was in the Pro Audio Repair business doing electronic repair on live sound large format mixing consoles. I do have scopes and meter's to measure with. 

However...not knowing where these test points would be, I would need some help.
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nrp3
Does this have a nexus controller and if so which one, A,B, or D?
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VNV1967
nrp3 wrote:
Does this have a nexus controller and if so which one, A,B, or D?


No This was Bought back in 2011. No Nexus controller was purchased. 

Anyway here's an update as of 5/21/20. Decided to go back to basics first. So this morning I went out and checked to make sure yhe Genny wasn't surging while running. Then I went to the CB's on the side of the unit and worked them back and forth thinking maybe the contacts had oxidized . 

I went back in the house and tripped the main pole feed breakers and the Genny fired up about 30 seconds latter. Had my Fluke plugged in to a kitchen output. I got a reading of 120 Volts steady and 60 Hz right from the get go. No more flickering. .....I ran the unit for about 1/2 hour. Steady as a rock. Yesterdays Volt readings were around 113 to 116 Volts. Today 120 Volts Rock Steady.

So I guess it was just oxidation some where. Would like to pull the trigger on the new Generac 10kw with Wi-Fi but Ziller is out of stock. Maybe that's why my Genny Straightened up. ðŸ
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DanS26
I have an older 10kW.  Voltage regulation on my unit is sort of strange.  With a light load you will see low voltage and flicker....the more load the higher the voltage and less flicker.  Maybe a tech can come by and tell us how voltage regulation works on these older units.

Strange but that is how mine operates.  Put more load on the machine and then measure voltage.

Good luck.
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murphy
The waveform of a 2 pole generator is not even close to a sine wave when unloaded.  As load is applied the waveform starts to smooth out but even at full load it is not a sine wave.  That is why a true RMS meter is required to measure the voltage.
Here is a trace of my old 2006 7 kW generator.

P9290324.jpg 
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UPS
VNV1967 wrote:




Thanks Buckshot, I would think I would need some direction in how and exactly where to check. I have the proper electronic equipment here as I was in the Pro Audio Repair business doing electronic repair on live sound large format mixing consoles. I do have scopes and meter's to measure with. 

However...not knowing where these test points would be, I would need some help.


Have you looked at the waveform your generator produces?  (Connect the scope through a small step-down transformer or AC wall-wart to isolate it.)  Is the waveform reasonably stable, even though it is probably distorted?
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VNV1967
I'll have to check that Saturday...Got an older scope  Tektonic which is 60 Mhz which should do the trick.. I have a large Iso Transformer sitting here collecting dust as I bought a Sencore "AC Power Right" Variac power supply for Power amp work which is also Iso-ed. Thanks For the tip.
UPS wrote:


Have you looked at the waveform your generator produces?  (Connect the scope through a small step-down transformer or AC wall-wart to isolate it.)  Is the waveform reasonably stable, even though it is probably distorted?
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VNV1967
DanS26 wrote:
I have an older 10kW.  Voltage regulation on my unit is sort of strange.  With a light load you will see low voltage and flicker....the more load the higher the voltage and less flicker.  Maybe a tech can come by and tell us how voltage regulation works on these older units.

Strange but that is how mine operates.  Put more load on the machine and then measure voltage.

Good luck.
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VNV1967
murphy wrote:
The waveform of a 2 pole generator is not even close to a sine wave when unloaded.  As load is applied the waveform starts to smooth out but even at full load it is not a sine wave.  That is why a true RMS meter is required to measure the voltage.
Here is a trace of my old 2006 7 kW generator.

P9290324.jpg 


I've measured the Voltage with my old Fluke 8060A True RMS Meter. So I know the out put is right on the Flike.
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ohmslaw
The voltage suggest that this unit has capacitors for voltage regulation.
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DanS26
When I self installed my 10kW Model 5502 in 2008 I checked the voltage with my Fluke 117.  First time fired up with no load I read 113v...it so concerned me that I called and talked to Generac tech (in those days you were allowed to talk to one).  I was advised that low voltage was normal with no load and to increase load to see if it changed.  Sure enough as I loaded the machine it progressed right to 120v and stayed there rock steady.

I think @ohmlaw is right and that these older machines use capacitors or at least one big capacitor for voltage regulation.
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BillM
I'm lucky I live right in their back yard.  I had a problem with their SMM product and knocked on their door, corporate HQ and then the plant and they came to my house and confirmed my troubleshooting.  Not sure that's easy to pull off all the time, but it happened to me last summer.
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nrp3
The point about the Nexus controller was I have a customer with A board control board unit that always had problems with hunting and flickering lights.  It had an A board control board.  I had spare B controller from a junked unit. I replaced portions of the intake and that took care of the hunting but the flickering remained.  The switch to the B board took care of the majority of the flickering. Whether this particular A board was bad, I’m not sure.  It sure behaves better now.  There will always be some dips in the lighting as large loads turn off and on but it shouldn’t be excessive. 
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DenisC
nrp3 wrote:
The point about the Nexus controller was I have a customer with A board control board unit that always had problems with hunting and flickering lights.  It had an A board control board.  I had spare B controller from a junked unit. I replaced portions of the intake and that took care of the hunting but the flickering remained.  The switch to the B board took care of the majority of the flickering. Whether this particular A board was bad, I’m not sure.  It sure behaves better now.  There will always be some dips in the lighting as large loads turn off and on but it shouldn’t be excessive. 

Do the Nexus A boards tend to have this kind of flickering more than say the D version of the board?  I have an A board that stopped charging for some reason.  I have a separate thread from a week or so ago on that.  I added a Battery Tender and that solved the charging problem.  Unfortunately the D board is a $700 expense on my generator.

But I do see flickering on my LED shop lights in the basement.  Hz measured with a Fluke 115 varies between 59 and 61 usually, in the loaded state

thanks in advance
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nrp3
It may be that later versions have better voltage regulation.  It did cure the flickering problem in this case to our satisfaction.  I don't know internally how much difference there is.  I'm sure the latest versions have different software as well.  It's hard to say how much it would help you or if it would.  Would solve the battery charge problem.
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