Fluttering Power

Yesterday, during Gaston, my electric power fluttered about 10 times, completely going off for a second or two about 5 times, but always came back on within a few seconds. I did not lose power as about 200,000 others had in the area. My question is what makes the power flutter, even going off for a second or two, without completely going off?

When there is a disruption in the power grid, the system tries to compensate by switching circuits around to minimize the effects of the outage. The “fluttering” is the momentary disruption when the circuit your house is on is switched over from one power source to a different one.

Another cause of fluttering is the successful operation of “reclosers” which are a sort of automatic self-resetting circuit breaker. If there is a momentary overload or short in a line from something like a tree branch brushing against the wire, the recloser will attempt to re-engage the power, rather than leave the line dead until a repair crew can be sent to reset it. Reclosers are usually a “3 strikes, you’re out” device - if they can’t get the line back on in three resets, they will stay off until the repair crew can fix whatever’s happened.

In most places that I’m familiar with, the distribution circuits are fairly simple. There isn’t any “grid” as such. You’re lucky if the branch is fed from two directions, and if there is a fault, there’s no guarantee that the other end will be able to pick up any part of the circuit. The much talked about “grid” is really just interconnections between the various power companies. It’s a grid on a large scale, not small scale. If New York doesn’t have enough power, Pennsylvania can supply a bit more and make up the difference. If a tree whacks the main distribution branch going through your neighborhood, well, you’re just plain screwed. It doesn’t matter how much power is available in the next state over.

If you are fortunate enough to be in an area with more than one power feed, if the one does go out, it will switch over to the other, but this tends to only happen once. It’s not going to wink and blink all day long. If the second feed goes out, the lights go out, and stay out.

Winking and blinking is usually the result of the reclosers that gotpasswords mentioned. Reclosers are often programmable, so they may be set a bit differently in your neck of the woods, but typically they try to reconnect the circtuit after one second, then three seconds, then thirty seconds, then give up. I’ve also seen them programmed to do three quick attempts at about one second intervals, then wait thirty seconds, then give up.

Since the most common faults during a storm are tree branches and lines getting blown against each other (both of which are very short duration faults) reclosers end up fixing most of the problems that would otherwise have you sitting in the dark.