Generator Fun: Follow-Up

Kill-A-Watt at 60Hz

The generator needed to be adjusted to provide a correct 60Hz output. Here I’m observing the frequency as the furnace cycles, and only small changes are seen in the a/c frequency.

Early in the week I mentioned that I had some issues running my natural gas-fired furnace using my generator — which has been converted to run on natural gas as well.  Experimentation proved that there was something wrong with the power being provided by the generator.  My family was lucky that the lights came back on on Sunday night, as we’ve heard stories of people without power for up to 48 hours.  This is horrible when temperatures are in the negative teens and windchills are in the neighborhood of -30F (windchill will increase how much heat is lost through the walls of the house–by the same convective mechanism that affects your body).  I also talked with a few people who had power, but were still having issues with frozen pipes.

I thought about my technical problem during the week and considered my actions to determine the exact problem and make a correction.  First of all, I knew we needed more extension cords, so I stopped at a hardware store and picked some up, along with some cheap cord-wrap organizers and some water-tight cord connector covers — which were what we should have used for weather-exposed connections used to power heat lamps for chickens and rabbits. I picked up a heavy-duty 12-gauge cord long enough to reach from the generator to the furnace.

The generator had been left out and plugged into the natural gas line, in case we needed it again. Note that the ball valve before the quick-release was disconnected to avoid any natural gas leakage.  With my sled/shelter protecting it, I wasn’t worried about blowing snow or rain getting into the control unit or the gas metering system.  Because I live on a dead-end street in the boonies, only one (trustworthy) neighbor sees the side of the house where it was parked, so I wasn’t worried about theft.

On Saturday, when I had some time for experimentation, I fired up the generator and plugged my Kill A Watt meter into it.  The voltage was right at 120V, so that was OK.  I looked at the frequency of the alternating current, which should ideally be at 60 Hz.  I found that the output was actually at just over 63 Hz.  On a common, inexpensive, non-inverting generator like mine, the frequency is actually set by the speed that the engine is turning the generator head.

Engine Governor Adjustment

To get the alternating current’s frequency to the ideal 60 Hz, I had to adjust the governor on the engine, as shown here.

To adjust the frequency, I checked the throttle mechanism on the engine and found the governor.  This was easily adjusted with a Phillips head screwdriver.  The tip is to make adjustments while the engine is running.  On my generator’s Honda engine, turning the adjuster clockwise increased engine speed and A/C frequency.  I would expect other brands to be similar.  I slowly turned the adjuster counter-clockwise until the Kill A Watt indicated 60.0 Hz.  Then I observed it for about a minute.  Even unloaded, the frequency will wander +/- 0.5 Hz, and the key is to ensure that that the range centers on 60.0 Hz.  After a little more tweaking, I was ready to try running the furnace on the generator.

After letting my family know what I was doing (and waiting for a load of laundry in the washer to finish its cycle), I shut off all the power to the house using the master switch.  I wasn’t sure that other energy sources weren’t used for the thermostat or any other systems, so I decided to simulate (create) a full blackout.  I ran the cord into the furnace room, unplugged the furnace from the wall, and plugged it into the Kill A Watt meter which was plugged into the cord.  I was in contact with my son via walkie talkie, and asked him to turn up the temperature on the thermostat so that the furnace would kick in.

The furnace started right up with no complaints.  I heard the exhaust motor spool up first, followed by the ignition sequence and the main blower motor.  As the generator was loaded up, the A/C frequency stayed in the 59.5 – 60.5 Hz range.  I expected more fluctuation, and was favorably impressed with the result.  Further cycling showed that voltage was constant.

I’m satisfied that I’m ready for the next winter power outage.  I’d say “bring it on!” except that many others in the area aren’t prepared in this aspect and I’d like to see human suffering minimized.  The lesson I’ve learned is that a system with any level of complexity should be fully ops-checked before it is needed.  That’s obvious, but I hadn’t tried this out, and I wasn’t as ready as I thought I was.  Now my Kill A Watt meter will be kept with my generator supplies, in case further adjustments are needed.

-Be smart: Try not to learn things the hard way!

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