songsc

It can be a phase to phase short circuit. My knowledge in electrical engineering has become rusty, but here are my thoughts:

Surge protectors works by shorting itself when the voltage becomes too high. They short themselves to lower the voltage on the line, protecting other equipments on the line. Common types are metal oxide varistor, where metal oxide will melt and become conductive upon high voltage, and gas discharge tubes, where gas becomes ionized hence conductive upon high voltage. Surge protectors have voltage/power rating which indicates the highest amount of power they can dissipate. If the spike voltage is too high, or the voltage spike lasted too long (“long” is not only time, it’s about the shape of the waveform too, RMS basically), the surge protector will blow out and other equipments on the line may be damaged. The expectation is that the main breaker on the line will trip before surge protectors blow out.

In a phase to phase short, two phases are connected together, which means two sinusoidal waves with 120° phase shift are superimposed onto each other. The end result will be voltage dropping, but in the transient event, there could be some power spikes, as the line and load aren’t perfect resistors. The reactance component (capacitance and inductance) can cause voltage spikes a few times higher than the main voltage when the main voltage changes rapidly. These voltage spikes likely triggered the surge protectors. Current on these two faulted lines also increases substantially as phase to phase short is essentially a short circuit, the phase angle between the two phases means that voltage on these two lines rarely equal to each other.

Another change is that since the 3 phases are no longer balanced, lots of current will flow through the neutral wire, slightly rising the voltage on neutral wire. This can damage some equipments too.

There are line differential relays in the substations to monitor phase to phase faults by comparing the current in each phase at different locations on the line, but it won’t react immediately when the short happens, as it usually need a few cycles to determine what exactly happened. By the time the relay decides to trip the circuit breaker, the voltage spikes may have already caused some damage to the surge protectors and equipments down the line. Short circuit calculations are often done using energy instead of voltage to account for the fact that main circuit breaker can not trip immediately upon fault, and it’s really the energy, not the voltage, that damages equipments.


Edit: Looks like a real expert has chimed in just above me

canadiancow

I have just enough electrical knowledge to have not-cheap surge protectors (i.e. most are manufactured by APC and have some level of battery backup) protecting everything that costs more than $100.

I also have a ring that conducts electricity. Maybe. I've never verified that.

Have you tried turning it off and on again? That's my usual solution for power outages.

Adam Smith

After reading this post, I feel like I'm halfway to being there too

expert7700

I'm no electrical engineer, but I can offer limited life lessons:

1) in 8th grade: if you don't like the school's new Apple IIgs computer, put a paperclip into the surge protector and wait for someone to turn it on

2) Don't plug a expensive US 120v device into a normal NEMA15 plug in Europe. I now have it on good authority that it will let the magic smoke out. (shh, don't tell Costco).
Was the squirrel ?

Civet

While on the topic of electricity, any of the electrical experts in here want to suggest a universal adapter plug, specifically one that supports rapid charging? I have issues charging my power bank while using my current adapter. Charges nearly 3x as quickly when plugged in without it.

RangerNS

So, we're getting some weather.

smallmj

We were grazed by the storm in my little town. Only 90 mm of rain in our meter this time. No flooding. Some trees down and only 36 hours without power.

Things are much worse to the east of us. My in-laws went for a drive east of Tatamagouche and saw a whole whack of cottages off their foundations. Big boulders that were placed to stop coastal erosion were just swept away.

Fun times

EmailKid

It did not look good on the news.

According to the news (US network news) it was the strongest storm to ever hit Canada

Of course I type this on a sandbar just off the coast of Texas just a couple of weeks past the height of the hurricane season .....

RangerNS

I'm right in Halifax. Damage is very isolated... Waking up, looking out the windows and I was wondering what the deal was.

But 2 houses away, a tree came down over the lines, and snapped a pole. A tree crew was here yesterday, put in 2 hours of work, but they need a couple of cranes to stabilize things before the trunk is removed and the repair proper can start.

smallmj

I believe it. My town is fairly close to the NS/NB border, so we didn't get hit nearly as hard as those to the east of us. That being said, most of the back roads near me are still without power, as well as the southeast side of town. Official estimates are that power will be back on by Wednesday there.

In Nova Scotia we are fairly well equipped to deal with strong-ish winds (gusts to 100 km/h) in winter when there are no leaves on the trees. When we get hit by much stronger winds in the early autumn when the leaves are still green then lots of trees go horizontal. And then there is the storm surge.

canadiancow

Anyone else watching the planetary defense test? 12 minutes to impact.

tcook052

Ever wonder why Edmonton's airport is called YEG?

Bohemian1

I watched the video.

Low production value and not much of a bang - Michael Bay would have done better.

YYC3722

Made me do a little digging for the rest of the story.
"With a few exceptions, airport codes starting with ‘Y’ designate Canadian airports. Edmonton International’s code reflects the city’s military history and comes from the nearby Canadian Forces Base, also called Edmonton Garrison."
https://www.air-port-codes.com/airport-info/YEG/

zorn

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