a nickel question.....

[brian john]

I would turn off the main remove meter and install safety glass/plastic in meter.

 

[mxslick]

..my lights flashed on, and
then off... and then, a minute later, again, and a minute later, again.

Actually Randy that would be the normal sequence for the POCO's automatic reclosers trying to clear a fault on the lines. They will normally try to restore the line three times then lock out, which isolates the section of the line with the fault. The idea being that temporary faults like animal contact or tree branches will burn clear and the line can be reclosed. A permanent fault (like the most likely thing with this sudden mini heat wave, a burned out transformer), will still be there after the reclose attempts.

The real fun for linemen begins where auto reclosers aren't installed and they have to try re-fusing a cutout to see if the fault is clear...big bang and impressive arc.

One time some years ago an underground line here faulted, and the POCO accidently reclosed a GOAB (Gang Operated Air Break) switch into the fault. The boom and flash was impressive enough to rattle my windows (and I'm two BLOCKS away from that switch) and it had the primary lines outside my window dancing violently.

ItsHot, be patient, that page takes some time to load up.

I would turn off the main remove meter and install safety glass/plastic in meter.

Not bad, but what if your meter has one of those big fancy locks on it, the POCO doesn't take kindly to people removing the meter, the POCO recloses a faulted transformer (see above) which could well send a nasty high voltage spike down the line while you're removing the meter or installing it or that safety cover...or you just plain forget to pull the meter or don't feel like doing it "just this once."

The whole point is that any action OTHER than the use of a proper transfer switch to connect a generator leaves open the possibility of a very dangerous mistake, which can kill a lineman. Even an experienced lineman can be caught off guard by backfeed, as shown graphically in THIS VIDEO.

Despite the open cutouts, what this copy of the video doesn't show (which the original video first aired on "Real TV" DID show) was that this bank of transformers was being backfed from another bank tied in up the street. When the force of that extinguisher displaced enough of the flaming oil, the backfeed created enough voltage and current to create that violent arc flash.

Too bad "Max X" had to have that annoying music and narrator running off, the original audio from that clip was chilling.

 

[hillbilly1]

Of course, turning off the main is a matter of faith as well.

Breakers are man-made devices, and do fail to operate as designed on occassion. So it's entirely within the realm of possibilities that even turning the main of fails to open the circuit.

You are so right, I'm not even real comfortable with the interlock kits, because if the main fails to open, (happens all the time with older equipment) The results could be deadly. I had an Orange box in northeast Florida that had lost partial power after a hurricane. We brought in a generator to get the store back up and running on three phase, since the majority of the A/C units were three phase. Opened the switch, but only two blades released, when checking for voltage to verify switch opened, I discovered this,and since the local utility was swamped with work, they could not pull off and disconnect the transformer to repair this. Needless to say the generator did not get hooked up to power the whole store. I had another big chain drug store that lost power after a tornado tore up the main lines behind the store. The main breaker would not budge to the off position, used the trip test button and was able to get it open, but only two phases. This time the POCO crews was working on the lines behind the store and had them cut the overhead service to the store.

 

[rt66electric]

refuse todo a dryer backfeed

refuse todo a dryer backfeed

we had a major ice storm, my buddies were calling how to do a suicide dryer cord.. I would refuse totell them how to do it. I would tell them it was much safer to it the old fashioned cord and plug way. For my coutry buddies who had gas or propane I would goto the furnace unit and remove the hard wire setup and refeed the furnace using a cord and recep. This set up was much safer and easier for there wives to do when they were stuck 75 miles away.
I could never sell a transfer switch becase of the price.

 

[peter d]

which is
fed off a 110 volt 2000 watt generator? both buses are fed thru each leg
of the 220 volt plug, the genset hasn't enough power to hurt anything,
and the house is fed...

This is obviously from the land of make believe, because I've never seen a 110 or 220 volt plug before.

 

[Fulthrotl]

This is obviously from the land of make believe, because I've never seen a 110 or 220 volt plug before.

sigh. oh, stop it. you win.

it's in californicate. carl explained it to you last month. remember?
flip flops, board rack on the service truck, not ladder rack?

hang loose, d00d.

 

[Fulthrotl]

Actually Randy that would be the normal sequence for the POCO's automatic reclosers trying to clear a fault on the lines. They will normally try to restore the line three times then lock out, which isolates the section of the line with the fault.

DWP does multiple reclosers, but to the best of my knowledge, SCE only
does once... 10 seconds after the peddler opens, the recloser ka-whams
it in an effort to hipot the line, and burn off the fault... if it doesn't work,
then the line patrolman has to hoof it out there....

these flickers were pretty weak, and didn't have the resounding oomph
you get from an edison reclose, so i was thinking it was generator magic, but
i could be wrong....

we'll never know..... it probably was edison just flailing......

one thing that is unnerving is being in a dwp distribution station about
8 am on a weekday, when all the blow dryers click on, and the mechanical
regulators go nuts trying to keep up.... that's when they grenade, in the
mornings..... the clicking and clacking is about as reassuring as hearing a
rattlesnake rattle.....

standard practice is go to outside for 15 minutes, and check something in
the truck.....

 

[mxslick]

Substations are evil...

Substations are evil...

DWP does multiple reclosers, but to the best of my knowledge, SCE only
does once... 10 seconds after the peddler opens, the recloser ka-whams
it in an effort to hipot the line, and burn off the fault... if it doesn't work,
then the line patrolman has to hoof it out there....

these flickers were pretty weak, and didn't have the resounding oomph
you get from an edison reclose, so i was thinking it was generator magic, but
i could be wrong....

we'll never know..... it probably was edison just flailing......

I'm under SCE here and all the reclosers (at least on my circuit) are 3-shot. I guess it would depend on what region and the oddities of the circuits in any area. The weak flickers seem to me to indicate either a failed transformer or hard short on the line somewhere.

one thing that is unnerving is being in a dwp distribution station about
8 am on a weekday, when all the blow dryers click on, and the mechanical
regulators go nuts trying to keep up.... that's when they grenade, in the
mornings..... the clicking and clacking is about as reassuring as hearing a
rattlesnake rattle.....

standard practice is go to outside for 15 minutes, and check something in
the truck.....

Remember the earthquake back in '88 (or was it '89?) I was living in Norwalk at the time, and I heard the chaos in the substation about three blocks away. I walked over there to find out the extent of the damage to our area (as my neighbors across the street had power right away and our side was still out.) Well, the first aftershock hit and the evil sounds from that substation from the follow-on faults had me running clear down the block, even the crew got out of there fast....

In all the years I've worked around electricity and all the various equipment failures I've witnessed and heard, I was never more scared that I was then. The noises defy description.

While living in Nor Cal, a racer's dad who worked for PG&E offered me an up-close tour of a substation. I couldn't work up the nerve to do it.

 

[LarryFine]

But as I read the original question, the generator could not energize the primary side of the transformer.

Sorry, but I wouldn't bet my life on your theoretical assurance. If someone managed to energize even one side of the service, it could still prove deadly upstream.

When any winding (or winding segment) is energized at its design voltage, every other winding (or winding segment) is also energized at its design voltage.

 

[winnie]

Sorry, but I wouldn't bet my life on your theoretical assurance. If someone managed to energize even one side of the service, it could still prove deadly upstream.

I agree. I would not bet my or anyone else's life on that point. I was just pointing out a particular feature of the originally described installation that would likely lead to something smoking on the customer's side rather than energizing the primary.

When any winding (or winding segment) is energized at its design voltage, every other winding (or winding segment) is also energized at its design voltage.

Agreed in general. Given this truth, what happens when you try to energize _two_ windings at the same time, but with relatively opposite polarity. Each winding is trying to energize the other; net result is essentially a short circuit.

-Jon

 

[Fulthrotl]

Remember the earthquake back in '88 (or was it '89?) I was living in Norwalk at the time, and I heard the chaos in the substation about three blocks away. I walked over there to find out the extent of the damage to our area (as my neighbors across the street had power right away and our side was still out.) Well, the first aftershock hit and the evil sounds from that substation from the follow-on faults had me running clear down the block, even the crew got out of there fast....

While living in Nor Cal, a racer's dad who worked for PG&E offered me an up-close tour of a substation. I couldn't work up the nerve to do it.

1989.. whittier narrows quake. i was working on an edison facility when the
quake hit, and an hour later, we got a request to go to the SCE corporate
offices, in rosemead, to safe off the building. nobody was inside when it hit,
all the offices had spline ceilings, and they were all on the floor.... it looked
like a nuke went off inside the building or something..... we were there for
something like 30 hours nonstop, cutting down fixtures, and capping flex
drops.

if ya ever decide you want to get that up close and personal look
of a powerhouse or generating station, lemme know.... tours are
available.....

 

[mxslick]

Whitter Narrows, hat was it!! Thanks...I do remember vividly getting literally thrown out of my waterbed by the initial quake...what a ride. And as the lines in my backyard were arcing, I ran around unplugging my electronics...a very stupid thing to do in hindsight, had a line come down onto the secondary or if the transformer in my backyard let go, I'd have had a handful 12.6kV!!

yeah, I 'll take ya up on that tour..and who knows, I may get brave enough to enter a substation now...but with my luck something will blow up when I'm in there.

 

[LarryFine]

if ya ever decide you want to get that up close and personal look of a powerhouse or generating station, lemme know.... tours are available.....

Absolutely! Is airfare included in that package?

 

[mxslick]

Absolutely! Is airfare included in that package?

LOL airfare and accomodations are the responsibility of the visitor, meals are extra, your mileage may vary, other restrictions may apply, this is a limited time offer, batteries not included.

 

[Fulthrotl]

Absolutely! Is airfare included in that package?

nope. neither is bail.....
i did mention these "tours" aren't normally scheduled by dwp, didn't i?

but there is some cool old stuff, like poured in place concrete 5kv switchgear
and control wiring from back in the 20's. the workmanship is amazing. no
telling how many hours went into lacing it up.... i'll see if i have some photos..

 

[iwire]

But as I read the original question, the generator could not energize the primary side of the transformer.

Jon,

What difference does that really make?

The line workers make repairs to the secondaries as well.