Portable Generator Waveform Comparison
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- Опубліковано 14 гру 2020
- In this video, we compare the unloaded waveforms of 3 popular portable generators:
1. Briggs and Stratton Elite, Model # 030210-02
2. BlackMax (a Homelite spin-off), Model # BM10700JR
3. Coleman PowerMate, Model # PM0645250
We accomplish this by hooking the generator output up to a Siglent SDS1202-XE digital oscilloscope. Fair warning - I am pretty new to this oscilloscope, and digital oscilloscopes in general so please be kind :)
NOTE: I had the scope probe on 10X but forgot to tell the scope that before taking these measurements - ignore the voltage readings.
The results were interesting... watch the video to see the results. Hopefully, as I learn more about this scope, I'll try and use the FFT function to calculate total harmonic distortion (THD) both unloaded, and loaded. Maybe compare the results with some other generators... Stay tuned... - Навчання та стиль
This video was very helpful to me today. I have a Generac standby generator, which is designed and marketed to power my house during a utility outage. It has an alternator similar to the ones in the generators shown here. It should create 60 Hz power, but my multimeter showed the Hz bouncing wildly all over the place. The problem was that these generators create shaggy power and the multimeter couldn't understand it. So the generator was just doing what it was built to do, but the test results looked strange and had me concerned for a while. The professional techs who work on these generators use better meters than the one I have. Thanks for making this video and leaving it for me to find. It was an important piece of the puzzle.
Another helpful video, thanks. May I suggest next time you're comparing waveforms...I assume your scope has an overlay feature, where you can have two different traces overlaid on top of each other (usually in different colors)? That would be helpful in say, comparing each wave to the direct AC waveform.
So I think there are some issues with this quick test and it just comes with all the pit falls of electrical tests. First when using a oscilloscope the negative lead is internally referenced to ground through the power cord. In this set up the generator is float ie not grounded. This can be dangerous as now the neutral of the generator now referenced to ground through the oscilloscope which it is not designed to handle much current. This can be fixed by using a differential probe or using a isolation transformer on the power cable of the scope. Talking about scopes your scope can perform a data capture, it would spit out a txt file in which you can then post process in matlab or excel to determine things like THD, current harmonics and other useful data. Power quality can be greatly improved with good grounding, insure the generator is well grounded. The generator should be tested in a no load and a full load condition. This can change its output waveform. Talking about loading generator how it handles reactive loading is also important. I guess what I am trying to say is that with a quick test like this it can be miss leading.
Thank you, I appreciate the feedback! Have any suggestions how I might learn to use this scope better? Quite honestly, the documentation that came with it (and that's online) seems like it is designed for electrical engineers. I am an engineer, but it has been a LONG time since I took any EE courses so I could use a refresher.
Okay, that was helpful. I had heard about the potential problems with non-inverter portable generators and how they may not be the best power source for "sensitive electronics", so I ended up buying a small inverter generator in order to run my computer and TV in the event of a power outage (with a non-inverter pulling the rest of the house). In fact I discovered this video by viewing your review of my new inverter gen elsewhere. The visuals gave me validation of the difference....so thanks!
No problem - most generator reviews I've seen oddly only look at frequency and voltage. They are important, but the waveform is as well. Glad you found the review helpful!
@@JoesGarageProductionsLLC Joe: This video from Dave Jones (Electronics Engineer) may help: ua-cam.com/video/xaELqAo4kkQ/v-deo.html
That noise is normally from the AVR turning on. Its normally half wave excitation . Portables usually implement capacitors for excitation or half wave rectification AVRs. They "turn on" usually @ the same phase angle.
nice video
Sir! You are the real Floridaman.
Bunyannnnn!! I did this exact experiment after my garage refrigerator stopped working, though, I didn't run a combustion engine in an enclosed space! CO poisoning is real man! Anyway, I saw a similar almost "sawtooth/jagged" waveform on my B&S Elite which I assumed is what killed the fridge. Hope someone chimes in with a solution...maybe a filter? Anyway, good to see a familiar face on youtube...keep the videos coming!
Carini... wow... been a long time... what, 20 years!!?? Hope all is well!
Thankfully I didn't win a Darwin award... I was careful to keep the shed door open and to walk outside when I felt like I was about to pass out.
Electric motors are notoriously sensitive to poor quality power. It can cause overheating, humming, and generally, really bad performance. The B&S Elite seemed to have the best waveform of the 3 i tested... my big concern is the "dead spot" that occurs every 2 periods. I'm planning to haul the genset out of the shed and into the garage to tear into it and see what's up. I have a hunch the AVR is toast but I won't know for sure until I hook the scope up in a slightly less toxic and nerve-wracking environment.
I am contemplating consolidating and selling these 3 portable gensets and purchasing one larger, higher-quality one... or perhaps swapping the gen-head for a higher-quality unit, like the Mecc Alte S20W-130. Stay tuned...
@@JoesGarageProductionsLLC Agree the B&S was pretty good but still had a lot of noise vs what comes off the line. Some pretty cool (and getting larger) inverter style generators out there that wouldn't have this problem. I will probably go that route or a whole house gen with a high quality gen set that can keep the THD down.
Any suggestion on. How to clean up the power?
Another thought on your utility power. You've got bursts at the top and bottom peaks which suggests to me that there is an insulator on a pole someplace that's arcing / breaking down / at the peak voltage. I bet if you turned on an AM radio you would hear the BUZZZZZ from that insulator problem. But it's very strange that you have such a distorted wave to start with. I wonder if the Siglent scope, or perhaps your probe, is distorting that?
My utilities are all underground here, but there are power poles in my back yard that *might* supply power to my neighborhood. Rumor is they are scheduled to get replaced by Florida Power and Light sometime in the next 400 years lol. How do I test to see if my scope/probe is distorting that? That's a bit beyond my knowledge unfortunately, but happy to learn and try.
@@JoesGarageProductionsLLC Not really sure if it would be easy to check. You would need some sort of known reference signal to look at. Your scope probably has a 'calibration signal' on the front panel, typically a 1 KHz 5 V P-P Square wave. You hook the probe onto that and there should be some small trimmers on your probe that you turn to show a square wave without rounding off the corners. I've not used a Siglent scope myself so can't tell ya much more than that.
@@Wheel_Horse yep I do see something like that. I'll mess around with it the next time I have the scope booted up. Thanks!
As Wheel Horse suggested, checking and adjusting your scope probe is a good thing to do to get the most accurate results. It is a single simple adjustment for the low frequency range looking at generators. And the warning someone else gave about your grounded scope and ungrounded generator is dangerous. Also the distortion in your utility power looks pretty bad. Figures it is FPL
I have a Briggs & Stratton open frame 5k Generator. I bought it second hand, never used, and I've never needed to use it for a power outage as I have other systems for short term power outages (Goal Zero). Lately I've been reading about the potential damage a non-Inverter Generator can cause to electronics. One solution offered was to run the generator power though a Line Conditioner in order to clean up the waveform. Is that something you've considered, or have any experience with. Thanks for you time.
I gave it some thought a while back but a high quality line conditioner is easily as much as a high quality generator. I would love it if manufacturers were more open about the quality of their generator heads... There is quite a bit of variation
Could the alternate wave irregularity on the Briggs be related to the engine firing every other revolution, since it is a 4-cycle engine?
It ended up being a problem with the AVR. My guess is probably a bad capacitor.
@@JoesGarageProductionsLLC Did you have some kind of external regulator connected when testing these ?
That "could" cause an issue but why would only one generator have that artifact ?
My bet is that the B&S anomaly is the spark plug emi being picked up by your scope probe.
Thank you for this video. I'm choosing between synchronous and inverter generator for backup and it was useful.
I'm pretty sure the strange spikes with the first generator have something to do with the spark. As far as I understand all those gens are using 4-stroke engines, so the spark happens each 2 revolutions. Probably there are some issues with generator's electric part, which could be resolved and the spikes are gone.
I thought the spikes might be coming from the ignition initially but just didn't line up with the waveform. I'm glad you enjoyed the video though and good luck selecting a generator!
Could you repeat the measurements with some load please? Thanks.
Can you run a test on DuroMax XP 13000EH? Thank you.
My neighbor down the street has one of those, I think... brand new. I'll see if I can get him to let me test it.
@@JoesGarageProductionsLLC please do
I would think the every other rev defect is probably when the spark plug fires.
What do the outputs look like under load - halogen flood lamp plugged into one socket, and how well do they match 60 Hz under load?
Good suggestion - I'll test that the next time I have these generators out of the shed!
I know Im pretty off topic but does anybody know a good site to watch newly released tv shows online?
@Peter Brycen try Flixzone. You can find it on google :)
@Daxton Harrison yea, been using Flixzone for months myself :)
@Daxton Harrison thank you, I signed up and it seems to work =) I appreciate it !
Coil interference?
Almost winner of Darwin award.
lol yup :)
wow, i never realized how shitty the output voltages on these generators are, i mean it's just a rotating magnetic field
Yeah I was pretty surprised as well. Not a very widely talked about thing either.
It's honestly sad. Because the rotating field winding and stator would produce a pure clean sine by themselves. The noise is created by the crappy AVR, which does not feed clean DC power to the field.
Look at the waveforms when the generator is under load. They'll be much worse. 5% THD at no load goes to 15%+ THD under load.
will a power cleaner work
Depends on how big/powerful it is. A smaller 120V model should be fine but a larger 240V commercial machine might be too much.
I would be more concerned about the DEFECT high voltage spikes like that can be several kilovolts and destroy electronic semiconductors instantly. Most likely cause if a dead spot on the slip rings where the carbon brushes momentarily arc out causing huge back emf pulses induced in the rotor & field coils. you might want to clean those slip rings 'James Condon' on youtube does that sort of thing all the time.
The high voltage oscillating spikes is what I was wondering about, too. Might go away by connecting a light bulb or resistive space heater as a load
suicide cord and darwin award all in one video. this is my kind of video.
seems like you would want to test these with a load on them
Yeah I would have liked to but I don't have equipment for that unfortunately. In South Florida we don't have a lot of electric space heaters
"We jammed in Joe's Garage... " Hey man, even the power from your utility looks like crapola! Quite a bit of distortion on that waveform. Our utility power looks like a perfect sine wave and I measured the THD from the PoCo to be right around 3% or so. My scope has the FFT resolution needed, and just today I measured a Generac GP5500 and was very unhappy to see that it had well over 20% THD. I suspect that all three of yours would be above 20% also judging from the look of the waveform. I think there's something wrong with the B&S generator. Every 2 cycles you have that spiking going on. That's not good because the spikes are well over 120VAC. "... we set up the drums in the front of the old Dodge, it was a '54 with a smashed up door..."
What scope are you using? Would love one that made measuring (or even calculating THD) easier/possible. The Briggs generator had a bad AVR module that I ended up replacing in another video. That eliminated that 2 cycle "weirdness". I also picked up another Briggs generator with a "low distortion" head that blows all of these generators out of the water. Still not as nice as utility power, but much better than any non-inverter portable I've tested.
@@JoesGarageProductionsLLC I'm using a Tektronix TDS 3012B. Not really a 'super high end' instrument, but certainly no slouch either. I believe that the resolution has to do with the number of bits in the A/D converters used. Not sure how many bits this one has, but it has been enough to measure THD on my machines (and audio equipment).
Wire winding error
I hate to write it, but this is mostly useless, since you measured these generators without a load.
Its cheating if a generator gives you 300Hz instead of 50 or 60 Hz.
All those generators are crap. I wouldn't run anything in my house with any one of those. Let alone the noise.....
Unfortunately, pretty much everything is crap nowadays. It all comes from greed.