Never having been privilege to the exact workings of power transmission and distribution, nonetheless can deduce the dynamics to which the unfamiliar terminology refers.  At former address (Euless TX) we had consistent/persistent outages in the 3-hour range.  I asked the utility for this kind of data.  All they sent was an incomplete/inaccurate spreadsheet down to which feeders were open.  Like it was either an embarrassment to them or some kind of national security secret.

FAASScinating.  As HAL explained in 2001, "This kind of thing has cropped up before, and it has always been due to human error".  Unlike in early-season Saturday Night Live spoof of 3 Mile Island, electricity is not just sent to your house to make toast.  The amount of power involved is well capable of destroying the equipment handling it.  Most conceivable fault/error conditions are anticipated and sensing/safety devices installed to interrupt power before the house burns down.  Like the breakers in your house only HUGE, networked, triple redundant.

The added complication also unfort'ly adds opportunity for failure.  Many/most of those potential failures are also anticipated and safeguarded, but it is not possible to map EVERY possible sequence of events.  When this kind of thing happens, like in aircraft crashes, they are analyzed in minute detail for the purpose of future prevention.  Thus "the grid" is as reliable as it is, despite being operated somewhat equivalent to driving your car almost as fast as it will go for hours at a time, day in and day out.

Give these PDFs a patient, redundant read.  Knowing what many here know of sequential control, you'll be able to make more sense of them than at first glance.

Car being only a coarse analogy.  That the system sometimes is going 'as fast as it can go' is derived from the times the utility comes on TV and begs us to reduce AC demand, or cycles us on and off.  Analogy breaks down in that, yes, that's nowhere near 'all the time'.  Still, it does happen and dependent on  weather extremes, with some regularity.  The system has to cut back to save itself.  The analogy is strong inasmuch as, if any underlying weakness exists in your car, operating it to its limit is more likely to reveal that weakness. 

These 2 particular failures were NOT caused by operating the system at or near its limit.  They were more like, you're driving along at 35mph and your cam belt breaks.  What happens next depends on engine design.  You either need a new cam belt ($1000 installed) or a whole new engine ($6000 installed).

Not to confuse anyone by drawing these analogies closer to familiar items, but to provide some context for understanding what to most would be about as alien as how flying saucers work. 

Somehow escaped an edit, was 'thanks Chet' for providing this.  And if/when I misstate, by all means straighten me out.  You know this stuff.  I can only about 3/5ths follow it.

Right there is a component I didn't know existed, much less that under ideal configurations it can reveal that it is failing before it actually does.

That's part of what I mean by "FAASScinating" [Leonard Nimoy's most exaggerated delivery].

My field was videotape.  Few voltages over 80VDC and none over 240VAC.  Power T&D is a whole 'nother world.  The crossovers are instrumentation/metrology, feedback, control.  Or I'd be pretty much lost.

Dad was apparatus sales engr/mgr for Westinghouse.  But he wasn't so much a talker at home.  More a yeller.

Meteor- and metr-.  Metr- being measurement.  Like the capacitive transformer.  In NTSC video we measured primarily in quarter cycles of 3.579545 MHz, which for mechanical parts can be counted down to horizontal or vertical rates. 

Early machines had to wait 16ms to measure vertical rate error and generate a correction, then another 16ms to see the result of the correction.  The result was overshoot and hunting.  From startup it took the machine ~5sec to sync to reference.

With the practical advent of digital logic (ca. 1974) it became possible to perform that vertical correction example in terms of horizontal rate or 64µs.  That is, the correction became a predicted ramp incremented at H rate and the next vertical sample error would be at or near zero.  Sync time now became 200ms worst case, 50ms nominal, a performance increase of 100x in a time-critical application.

In practice, the correction ramp was updated at capstan optical tach rate, ~3KHz or every 5 horizontal increments.  The capstan being the mechanical timing element for vertical rate.  Full lockup included horizontal timing and a similar method was applied to the rotary transducer (headwheel).

Just the metrology, principally measuring/correcting timing/positional errors in electromechanics.  Broadcast video is a pretty-well controlled environment.

Having this many closed loop mechanical systems in one machine made for some very entertaining times.  Whether watching it work or watching it fail and figuring out why.  This machine was so precisely constructed that most subassemblies could be removed and replaced exactly back where they belonged with 2 or 4 allen bolts.

Lotta useless knowledge now, broadcast today employs no user-serviceable moving parts.  BOOOOR-ing. 

Link is to a video of the machine sequencing short segments from various angles.  It rewound/replaced the played tape exactly where it found it, loaded and cued the next one in 7 seconds.  That carrousel that holds the cassettes could literally take your arm off if you got in the way.

Videography not the best.  And it was pretty inadvisable to shine bright lights inside it while it was running, as many of the sense elements were optical.  The operational sounds it made are downright musical.  The machine and I were each other's best friends.

Only one station had the Ampex machine.The others used RCA

Many markets were like that.  The Ampex machine cost about twice what the RCA cost.  It was much faster, smoother and more versatile but 'most' stations just wanted 'a cart machine' and beyond that they didn't care. 

I went to work at NBC-OKC precisely because they were an Ampex house.  We had 4 generations of Ampex 2" recorders, from the first transistor model to these digital ones to the next digital one (AVR-3) and from there 1-inch was taking over, largely because the tape cost less than half as much.  I knew all of them inside and out, as well as 3 generations of audio machines, switchers and effects boxes, all the associated Tektronix instrumentation.  The transmitter guy did only that, couldn't fix a monitor.  Fine by me.

Power is 10:1 step DOWN?  That's not how we used to do it, is it?  Station got SS Larcan (VHF 4) just before I left.  I had some idea what went on in the old RCAs.  No idea what goes on in SS.  Or digital.  Pay me $60K and I might care.

Ampex was not ALL genius.  Here's a dirty story about VR 1100/ VR 2000, the ones there were the most of.  You could spend all day or all week aligning the servos and the machine still wouldn't lock full V&H on any tape but its own.  Everyplace I worked had at least one machine with this problem.

Turns out they had specified the capstan to a very tight tolerance.  BUT the motor and flywheel pulleys had just as much to do with tape speed and their tolerances were 'generous'.  If the pulley tolerances stacked, the velocity loop would go all the way to end of range, leaving nothing for the phase loop to work with and it would stall just outside vertical lock.  Which also inhibited horizontal lock and playback would be unusable.

That's the only problem I never solved by myself.  Never imagined 'wrong size pulley' was possible.  Read about it in an industry mag and sure enough, replaced the entire capstan assembly and it worked right for the first time in 20yrs.

Not to diminish Ampex achievement.  Complex as they were, they made very little trouble over very long lifetimes.  The story on RCAs was, jigger this, jigger that, it was always something.

I love it too.  Revisiting that video raised my spirits.  Sounds daft, but I miss that machine.

Those too.  Wish I had my 1973 Panasonic twintub back.

Besides the nostalgia, there were practical elements.  That machine doubled my salary in return for reducing its failure rate from

1 commercial lost per day, to 1 per week.  The chief kept records of that.  It also let me have on-call weekends off. 

BTW there were two of them and both were that well behaved once I got ahold of them.  The guy before me was 'good',

but I'm obsessive when it comes to machinery.

4160 eh?  Count me out.  I'm not too uncomfortable with 25~30kV monitors, the danger parts are well known, easily avoided.  Even if they do bite you, there's no real oomph behind it. 

Nothing like power mains can do.  Anything over 240V is pretty unforgiving.  One false move is all it takes.  When you get up in the kVs, that shxt doesn't necessarily wait for you to blunder into it.  It can leap. 

Thanks, I'll maintain social distance as the phrase goes these days.   To me, social distance from 4160 is in the next room. 

With the door closed.

We have had one guy get killed out here and that's enough

Pardon the expression, that'snuff for me too.  Not the scaredy type, but certain levels of danger I'd sooner avoid.

I was fine with heights.  Climbed straight up the front of Diamond Head hand over hand, cliff jumping into water, going up 1400ft tower elevators.  Until the third time.  Suddenly I was terrified and have been ever since.  Now get a little shaky just watching 'Emergency'.  What changed?  Turning 40 maybe.  Lost my immortality.

More people are killed by chevrolets than ferraris.  Not because chevrolets are that much more dangerous,

there's just a helluva lot more of them.

I've brushed across 120V a number of times.  Gets my attention, is about all.  Bee sting hurts worse.

Graciously, my skin resistance is over 10X normal.  That doesn't help much at 240V and not at all at kV.

Neighborhood (distribution) levels should be 7~14kV.  Austin was 7.2k; I hung out with some line guys, told me that.

Then there's lightning.  Unmeasurably high voltage and current, yet only kills an average of one in ten people it strikes.

Friend had a Tesla coil.  Don't know what the freq was.  Threw about an inch arc.  Could touch it with your finger, no sensation of shock at all.  But when you looked at your finger there were holes burned in it.