4 ms·

Somewhat related anecdote: I live in the Finnish countryside, and since much of the power grid out here is still ancient, there are power outages rather often.

by ahje 7y ago

Somewhat related anecdote: I live in the Finnish countryside, and since much of the power grid out here is still ancient, there are power outages rather often. However, if the power goes out, there's always something that tries to power everything back on automatically after exactly 30, 60, 120 and 240 seconds. If something's still wrong, the power will simply flick on and then off within a few seconds. If an outage lasts more than four minutes, it usually takes much longer to get it running again (I assume it's because it then triggers an alert that will be handled by a human operator). I would assume there's a lot of similar stuff going on in the US power grid, considering it's immense size what I suspect is a somewhat similar mix of new and very old equipment. And yes, surge protectors are mandatory here.

cesarb 7y ago
> there's always something that tries to power everything back on automatically after exactly 30, 60, 120 and 240 seconds Sounds like a recloser, which tries a number of times to restore power under the assumption that most faults are transient (for instance, a branch falling in the wires and then sliding to the ground). After a set number of retries, it gives up and stays open; at that point, a human has to locate the fault, clear it (for instance, poking the fallen branch with a stick until it falls to the ground), and then tell the recloser to close the connection again.
- ahje 7y ago
  Yes, that sounds to be it. I can imagine such systems takes care of quite a lot of incidents in large power grids.
throw0101a 7y ago
> If an outage lasts more than four minutes, it usually takes much longer to get it running again (I assume it's because it then triggers an alert that will be handled by a human operator). I read a statistic at some point (which I can no longer find the reference for) that power outages tend to be bimodal: either they last a short time (e.g. <5min) or they last a long time. There's hardly anything in between. In the US, utilities report outages longer than five minutes: * https://www.eia.gov/todayinenergy/detail.php?id=35652 https://www.eia.gov/todayinenergy/detail.php?id=35652

by ahje 7y ago

cesarb 7y ago

> there's always something that tries to power everything back on automatically after exactly 30, 60, 120 and 240 seconds Sounds like a recloser, which tries a number of times to restore power under the assumption that most faults are transient (for instance, a branch falling in the wires and then sliding to the ground). After a set number of retries, it gives up and stays open; at that point, a human has to locate the fault, clear it (for instance, poking the fallen branch with a stick until it falls to the ground), and then tell the recloser to close the connection again.

ahje 7y ago
Yes, that sounds to be it. I can imagine such systems takes care of quite a lot of incidents in large power grids.

throw0101a 7y ago

> If an outage lasts more than four minutes, it usually takes much longer to get it running again (I assume it's because it then triggers an alert that will be handled by a human operator). I read a statistic at some point (which I can no longer find the reference for) that power outages tend to be bimodal: either they last a short time (e.g. <5min) or they last a long time. There's hardly anything in between. In the US, utilities report outages longer than five minutes: * https://www.eia.gov/todayinenergy/detail.php?id=35652 https://www.eia.gov/todayinenergy/detail.php?id=35652