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We've had a blackout!

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JohanH:

--- Quote from: RoGeorge on June 11, 2022, 06:26:42 pm ---https://library.e.abb.com/public/d9a7af4fb84394e8c125754d003393dc/RK85-201E_en_Auto-reclosing.pdf

--- End quote ---

That's an old manual. :) But principle is the same today. Modern relays are digital, e.g. ABB 615-series and 640-series protection relays. There's even a centralized protection unit now, which is very high tech: https://new.abb.com/medium-voltage/digital-substations/campaigns/smart-substation-control-and-protection-ssc600
This is basically an embedded PC with all protection functions running in software. I think this is unique product so far. They tried this already in the 90's, but PCs were not fast enough at that time.

tooki:

--- Quote from: RoGeorge on June 11, 2022, 06:26:42 pm ---A blackout is called when a large area remains without powered for much longer periods of time.  At less than a second, I'd call that a power surge.

--- End quote ---
A surge is the polar opposite of an outage: it’s when voltage briefly goes much too high (voltage transient).

Some terms for brief outages I found on power companies’ sites are “momentary outages”, “momentary interruptions”, and “short duration interruptions”.

james_s:

--- Quote from: RoGeorge on June 11, 2022, 06:26:42 pm ---A blackout is called when a large area remains without powered for much longer periods of time.  At less than a second, I'd call that a power surge.

At less than a second, you probably witnessed a successful auto-reclosing event.

In every power distribution stations there are automated protections at the end of the lines, and they can talk with each other.  These are, briefly said, devices monitoring the voltage and current (and thus the impedance) on the ends of the power transmission lines.  They can detect many types of failures, distance to the defect, etc. and engage different protection mechanisms accordingly.

One of those mechanisms is to trip the power for a fraction of a second only, then to automatically try to reconnect the line to power again, in the hope that maybe it was just a bird that got pulverized by the electric arc, or maybe a lightning strike, and the circuit is now good again.  That's the auto-reclosing protection:
https://instrumentationtools.com/auto-reclosing/
https://library.e.abb.com/public/d9a7af4fb84394e8c125754d003393dc/RK85-201E_en_Auto-reclosing.pdf

--- End quote ---

The auto reclosers here typically trip open for about 10 seconds, then they make one attempt to close the circuit, and if the fault remains they lock out. It creates the somewhat annoying situation where the power goes out for just long enough to mess up all the clocks and reboot anything not on a UPS, but it's better than the old days when a fallen branch would just blow a fuse and the power would be out until somebody reported it and the utility would come out and fix it.

jogri:

--- Quote from: Messtechniker on June 11, 2022, 02:49:28 pm ---Seems to have happend in Germany where blackouts are extremely rare.

--- End quote ---

Yeah, about that... Maybe rare in big cities, but in my town (~10k inhabitants, so not some small remote village) i have roughly one total blackout per year that lasts from 30 minutes to 12 hours and a couple of brownouts/short disruptions that last a few seconds every few months. And those blackouts are usually at night so it's not load shedding due to high demand. Just a really shitty power grid at work that should've been rebuilt half a century ago but no one could be bothered to do that (it costs money, you know).

RoGeorge:

--- Quote from: tooki on June 11, 2022, 07:10:02 pm ---A surge is the polar opposite of an outage: it’s when voltage briefly goes much too high (voltage transient).

Some terms for brief outages I found on power companies’ sites are “momentary outages”, “momentary interruptions”, and “short duration interruptions”.

--- End quote ---

My bad, sorry, I didn't know the correct En translation.  In Ro the most used is "voltage drop" (can be drop to 0V or drop to lower than nominal), while when it's for more than a couple of seconds the popular term is "the current has been taken".



--- Quote from: james_s on June 11, 2022, 07:44:08 pm ---The auto reclosers here typically trip open for about 10 seconds, then they make one attempt to close the circuit, and if the fault remains they lock out.
--- End quote ---

About the 10 seconds wait before reclosing, I'm an electronist by profession, not electrician, didn't even know it can be that long, thanks for mentioning that.

It happens that I know about line protections only because we were implementing SCADA systems in a few power distribution stations here, in Romania.  I remember very fast reclosures times (during the acceptance test), less than a second.  Or maybe it's yet another mistranslation of mine (in Ro it's RAR, standing for Reanclansare Automata Rapida, and meaning Fast Auto Reclose)?

Googled and found this classification (in a Ro link)
- ultrafast, tRAR=0.1-0.5s ;
- fast, tRAR=0.5-1.5s;
- slow, tRAR>1.5s;  which I didn't know before

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