A recent event in New York made me think of one of those times I played tourist in New York.
This is my review of Barrier Brewing Riprap Baltic Porter (H/T Iobot)
Why was I wandering around Manhattan when I was 19? To be honest it was a family vacation and we were passing through. It was one of those things we sort of decided on the fly because we were on our way to Maine. Lower Manhattan experienced a small outage that particular day which prompted us to leave and seek refuge in Connecticut. But about a year later….
Fifteen years ago today, at about 4:10 p.m., New York City was suddenly powerless, as all electricity disappeared when an overgrown tree branch hit a power line in Cleveland (and a utility company’s alarm system failed). Eight northeast states, plus Ontario—in total more than 50 million people—were plunged into darkness.
While they had to endure about 30 hours without electricity, New Yorkers turned the blackout into a moment of urban solidarity: Citizens started to direct traffic since traffic lights were out; they helped each other out of trapped subway cars; welcomed in stranded colleagues who couldn’t get home; restaurants held impromptu cookouts, sharing their food and beer with neighbors.
It wasn’t all fun: 413 subway trains and 400,000 passengers were stopped and all needed to be evacuated. That process took almost three hours, and a federal report noted, “Unfortunately, the passengers flowing into the streets from underground met a massive amount of congestion in the streets and on the sidewalks due to the volume of vehicles and pedestrians.”
Now high voltage troubleshooting is similar to troubleshooting any circuit. You start at the affected point, test for voltage to phase to phase, phase to ground, phase to neutral, and neutral to ground. Each test has an “normal” reading, the actual reading provides a clue to the problem. The hart part is accessing the circuit since its suspended on poles or underground. Thankfully the circuit is big and easy to see, especially if it is overhead.
So why did this outage last for as long as it did? According to the Electrical Schoolhouse at the 366 Training Squadron, Sheppard AFB, TX: this was a “really, really, really big circuit.” One of the civilian instructors had this satellite photo made into a poster.
The Department of Energy had this to say:
Transmission lines are designed with the expectation that they will sag lower when they become hotter. The transmission line gets hotter with heavier line loading and under higher ambient temperatures, so towers and conductors are designed to be tall enough and conductors pulled tightly enough to accommodate expected sagging and still meet safety requirements. On a summer day, conductor temperatures can rise from 60°C on mornings with average wind to 100°C with hot air temperatures and low wind conditions.
A short-circuit occurred on the Harding-Chamberlin 345-kV line due to a contact between the line conductor and a tree. This line failed with power flow at only 44% of its normal and emergency line rating. Incremental line current and temperature increases, escalated by the loss of Harding-Chamberlin, caused more sag on the Hanna-Juniper line, which contacted a tree and failed with power flow at 88% of its normal and emergency line rating. Star-South Canton contacted a tree three times between 14:27:15 EDT and 15:41:33 EDT, opening and reclosing each time before finally locking out while loaded at 93% of its emergency rating at 15:41:35 EDT. Each of these three lines tripped not because of excessive sag due to overloading or high conductor temperature, but because it hit an overgrown, untrimmed tree.22
A recloser is a device, as the name implies, designed to immediately close the circuit in the presence of a temporary fault, within the device’s safe capacity. Ever notice the lights flicker once, twice, three times, and then go out? That is a recloser in action. Phase to phase voltage on a standard 7,200v circuit should read around 12,470v; as a idea of what the fault voltage could theoretically be. The immediate fault voltage should be high enough to either burn the branch shorting it, or at least bump it off, and continue providing uninterrupted distribution.
This was 345,000v line. Next time you are around one of the towers, consider how tall the towers is, how low the lines sag, and how tall that tree had to be. Then consider why there are never any birds on that wire (induction).
The massive recloser in Ohio worked as designed, it closed three times and locked open. This caused a voltage drop on that circuit, and every other circuit it was back feeding. Affecting distribution in the most densely populated part of North America, on a warm summer afternoon. That had to suck.
What does not suck is this beer; it is a Baltic Porter. It has a high abv of around 10%. It is somewhat heavy in body but unlike a stout it is not an overwhelming coffee or chocolate, the high alcohol content certainly drowns a lot of spices and flavors out. Definitely not one to chug, especially on summer day. Nice call Iobot. Barrier Brewing Riprap Baltic Porter: 4.3/5