TL;DR: Look for a screw adjustment attached to the throttle. Use a decent multimeter to monitor the frequency when you run your generator. (I love my Fluke 177.) Keep an eye on frequency and tune as needed— 60 Hz in North America. If you don’t want to play with a multimeter grab a Kill-A-Watt.
Here’s my video of what happens to frequency on a rough start, I need to clean the carburetor: https://youtu.be/L55L_UXpfR0
Long Story
I bought a 1200 Watt Powermate portable generator Walmart special in mid-2015. I couldn’t have paid more than $150 for it. It has a manufacturing date of 2015 which is important, it is after Generac purchased Powermate. The exact model is not manufactured anymore but I have taken very good care of it.
The only thing that is wrong with this little generator is that the carburetor needs to be cleaned and I should replace the spark plug. I can get it to start in 3 pulls if I use the choke as a tuner for the first minute or so.
Taking care of a small gasoline/petrol generator is easy:
- Run it at least every couple of months.
- Check the oil. (I run a full synthetic. YMMV.)
- Use fuel stabilizer.
- Find a balance between burning old fuel and having enough on-hand.
- Buy ethanol-free fuel if possible. (I can’t find any within a 45 minute drive and it’s not worth a special trip.)
- Clean the carb.
- Keep it out of the elements unless you need to run it.
Ramblings on Phase
In North America, AC power distribution is 60 Hz. Most US homes have known what is “split-phase” which is a single-phase 240 V feed that gets tapped in the middle (like cutting it in half). The two legs are not actually out of phase, they just look like they are 180 degrees out of phase when measuring relative to neutral because it is cut in half! Measuring potential between legs will show 240 V!
There is a chance that if you live in a converted industrial or commercial building that you have 3-phase power — 3 phases of 120 V out of phase by 120 degrees each or (2π/3) radians. If you combine 2 phases you get 208V.
Excuse my ugly 3-phase drawing…. But it’s important to understand why any two 120 V legs combined equals 208 V in the 3-phase example.
Anyway, 3-phase in the US is usually a wye or a delta configuration. Wye has a neutral, delta does not. In both cases the three phases are all 120 degrees out of phase. Combining any 2 phases results in 208 V.
Remember the 120 V measurement is RMS (root mean square). For a sine wave, RMS is the amplitude * 1/sqrt(2) or about 0.707. To convert back to the amplitude, 120 V * sqrt(2) = ~170 V (max amplitude)
So how does adding two 120 V RMS legs get you 208 V RMS? Adding two sine waves at the same frequency but shifted by some phase is straightforward.
Line 1 f(t) = 170 V * sin(2π * 60 Hz * t)
Line 2 g(t) = 170 V * sin(2π * 60 Hz * t + (2π/3))
Without getting into the 2nd order differential proof, the combination is below:
ψ = arctan((170 V * sin(2π/3)) / (170 V + 170 * cos(2π/3)) = 1.0472
Amplitude of the combined sine wave = 170 V * sin(2π/3)/cos(ψ)
= 170 V * sin(2π/3)/cos(1.0472) = 294.449 V
Convert to RMS => 294.449 * 0.707 = 208.176 V!
Stay tuned for more!
