I ran the generator first unloaded then I ran it with load. Here are some pics. First is straight utility for a baseline, then the genset with a little choppiness unloaded, then with it loaded some and you will see the waveform becomes disfigured. My genset is a blackmax model bm903500. 3550W rated, 4550w surge. I believe it has a Honda engine.
Hz question
- Thread starter Onsite_energy
- Start date
- Status
I ran the generator first unloaded then I ran it with load. Here are some pics. First is straight utility for a baseline, then the genset with a little choppiness unloaded, then with it loaded some and you will see the waveform becomes disfigured. My genset is a blackmax model bm903500. 3550W rated, 4550w surge. I believe it has a Honda engine.
- Location
- Massachusetts
What type of load was applied?
To me it seems much more likely you are seeing effects of the load itself not the governor.
Can't remember exactly, but the loads I run on the generator are refrigerator, oil furnace, modem/router (small ups I think is also on it) and some lights. The lights would be CFL, linear fluorescents, and maybe a couple incandescents. I imagine during this test, these loads were probably running. The generator output is 120V 30A. The generator governor is mechanical with an idle bar and spring. I also actually run the generator under load every other month for about a 1/2 hour. I put a couple lights on it, a couple motors, and whatever else I have lying around. Just plug right into the genset. After I run it, I turn the fuel off and let it fuel starve to shut off to keep gas from setting in the carb. The carb does have a bolt to drain the fuel, but don't like putting that in and out. Would like to find a fitting like you would see on an old tractor carb where you can twist a Tee handle to open a drain hole in the center. I also want to get a 3-way tee for the fuel line so I have an easy way to drain the gas out of the tank after a run.
Last edited:
Carultch
Senior Member
- Location
- Massachusetts
How do you calculate the combination of those two variations? Additive? Multiplicative?
- Location
- Massachusetts
I am kind of new to this but from what I am learning all the loads with SMPS (switch mode power supplies) Modem/router, UPS, CFLs, and the linear flourescents if they have electronic ballasts will distort the sine wave.
High impedance source like a gen set have a significant role to play in distortion of the output from it in addition, when supplying nonlinear loads. Need more experience or learning. :dunce:
You are correct, but you typically get spikes and dips kind of like the unloaded sinewave as opposed to a chopped sinewave. Maybe someday I will load it with purely resistive loads and perform a similar test. Buy a couple electric resistive heaters and make a more reasonable load bank.
- Location
- Massachusetts
There is a picture of a fairly clean sine wave from the unloaded generator.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
The current wave is definitely not a sine wave from those loads, the voltage wave will not change unless you have a pretty significant non linear load for the size of the source (I think).
- Location
- Massachusetts
That's great, that means you are very knowledgable about this subject and we can expect your next post to be answering the OPs question.
The OP's question in your words?
Onsite_energy
Member
- Location
- Englewood fl
Ok so here's what I found, I'm guessing that the governor runs off voltage...... Idk I never had one throw me for a loop like this....under full load 100amps, (50per side) as I apply load to full it goes from 63hz up to 64.5 "1900 rpm" bounced between 119&121acv this is a single phase not 3 ... I know as I started shutting down the load bank it would drop rpm never go over 121v per side.... When you first star it its at 130v put 2kw to it, it dips to 121 with a few dips to 119.... Every,brush,slip ring ,every connection I ohmed was 0000 it does say "standby not prime mover.... Can someone just verify 1 more time if the Hz will hurt anything.... This is for small business and when you throw the transfer switch everything seems to be fine voltage wise inside.... This is a new acct I picked up so new to me....
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
If you reduce the no load speed of the gen set, the frequency will drop. Set the frequency then to 60Hz and voltage to 120/240V. Prepare a table for frequency and voltage. Apply load to the gen set and record values of frequency and voltage for various loads. The maximum frequency change is 3 cycles and voltage 10% and combined variation of frequency and voltage 10%.
IDK, I haven't met that 3 cycle thing that you are prescribing.
The usual droop setting that I use is around 3%. What that means is that if the genny was set to run at 60 Hz unloaded, it drops to 58.2 Hz when loaded full. Also, the terminal voltage gets to be controlled by the AVR not the governor.
Onsite_energy
Member
- Location
- Englewood fl
If I lower the cycles to 60 the voltage drops to 118v on one side and 119 on the other side.... Unloaded , load it and voltage drops... Using all fluke meters to monitor and a avtron load bank.... I have no breaks in wiring ,everything ohmed 000.0 this thing acts like it was overloaded or something but I can't see a problem that would make it do such low voltage at 60 cycles it won't make it 120v until 63 .... This is a good size diesel genset maybe avr bad????
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
118 or 119 is completely within the tolerance for a nominal 120V system from POCO. Why are you expecting something tighter or better centered from a genset?
I suspect that there is an adjustment somewhere in the bowels of the AVR circuit that would allow you to bump it up to 120. Just not found on the front panel.
What is interesting (but not at all unexpected for an analog control system) is that the AVR is not able to compensate completely for the speed dependent voltage from the generator for a fixed field excitation.
Onsite_energy
Member
- Location
- Englewood fl
Hz question
Im just use to 3 phase gensets and I haven't worked on a single since.... Holy moly let me think .. 1999... Just use to ATS setting and 480 but I like to learn and do things the proper way so the dumbest question is the one not asked
but yeah Idk why at 60hz it not at 120/120 but if 118/119 is good I'll take it! I just don't want the guys sh*t to fry cause of not enough amps
Sent from my iPhone using Tapatalk
Im just use to 3 phase gensets and I haven't worked on a single since.... Holy moly let me think .. 1999... Just use to ATS setting and 480 but I like to learn and do things the proper way so the dumbest question is the one not asked
but yeah Idk why at 60hz it not at 120/120 but if 118/119 is good I'll take it! I just don't want the guys sh*t to fry cause of not enough amps Sent from my iPhone using Tapatalk
Please post the AVR make and model. Perhaps there are other ways to tweak that thing.
Onsite_energy
Member
- Location
- Englewood fl
I've never seen one like this before
.... That a transformer? Lol I think I found the problem
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
- Status