The other night our power went out here in Oakland. Was watching teevee
when the lights went out all of a sudden. Then they came back on. Then
they flickered a bit and went out again. Came on again, there was a
muffled "BOOM!", whereupon they went out, this time for good.

It was the first power outage we'd had here in a long time. And I
noticed some really strange things.

First of all, the "BOOM!" turned out to be a transformer which exploded
rather spectacularly right outside the building I'm in. Some neighbors
down the street said they actually saw the thing go, sparks and all.

Turns out there were several other transformers all over town that blew
at (about) the same time. Power was out to 4,500 customers at the peak
of the outage, in an area covering many square miles. But walking
around, I'd see blocks on end without power and with no streetlights.
Then there'd be a block with power. And some of the blacked-out areas
had working streetlights. The local power grid must be a crazy quilt of
wiring.

Regarding the cause of the outage, when I got ahold of PG&E (Pure Greed
and Extortion), the guy said it was due to "equipment failure". Talking
with my neighbor, though, he said he though it was human error: someone
threw the wrong switch or something.

And really, how else could a transformer fail spectacularly, other than
an overload, except by there being some kind of massive overvoltage
surge (what people incorrectly call a "power surge")?

OK, so for the rest of the evening we were without lights. Sort of.

Sort of? I though power outages were pretty much black and white: either
the power is on or it's off.

Not so, grasshopper. I stuck my VOM into an outlet and monitored the
line voltage. The reason I did this was that after the power had been
off for a good long time, I heard my microwave squealing a high-pitched
whine. And there was noise coming from the fridge motor. At that point,
I could see that there was about 60 volts on the line, enough so that
when I turned the lights on, they came on, sorta dimly.

After that, the line voltage fluctuated wildly, going from a low of
about 45 volts all the way above 80. My guess is that they (the power
co.) were switching things in and out, and that was causing the ups and
downs. Another unusual thing I noticed was that my neighbor's diesel
generator kicked in when the power went out (they have a small server
farm they like to keep alive). But every time the voltage went above 80
volts, the thing would turn itself off--which meant that they were
running on low voltage for at least part of the time.

I found out that my TV (old analog) and DTV converter work fine on about
75 volts. I didn't want to find out about my computah, so I turned it
off. Also turned off the fridge because I didn't like the sounds I heard
coming from the compressor.


--
Made From Pears: Pretty good chance that the product is at least
mostly pears.
Made With Pears: Pretty good chance that pears will be detectable in
the product.
Contains Pears: One pear seed per multiple tons of product.

(with apologies to Dorothy L. Sayers)

On Mar 29, 9:55�pm, David Nebenzahl wrote:
The other night our power went out here in Oakland. Was watching teevee
when the lights went out all of a sudden. Then they came back on. Then
they flickered a bit and went out again. Came on again, there was a
muffled "BOOM!", whereupon they went out, this time for good.

It was the first power outage we'd had here in a long time. And I
noticed some really strange things.

First of all, the "BOOM!" turned out to be a transformer which exploded
rather spectacularly right outside the building I'm in. Some neighbors
down the street said they actually saw the thing go, sparks and all.

Turns out there were several other transformers all over town that blew
at (about) the same time. Power was out to 4,500 customers at the peak
of the outage, in an area covering many square miles. But walking
around, I'd see blocks on end without power and with no streetlights.
Then there'd be a block with power. And some of the blacked-out areas
had working streetlights. The local power grid must be a crazy quilt of
wiring.

Regarding the cause of the outage, when I got ahold of PG&E (Pure Greed
and Extortion), the guy said it was due to "equipment failure". Talking
with my neighbor, though, he said he though it was human error: someone
threw the wrong switch or something.

And really, how else could a transformer fail spectacularly, other than
an overload, except by there being some kind of massive overvoltage
surge (what people incorrectly call a "power surge")?

OK, so for the rest of the evening we were without lights. Sort of.

Sort of? I though power outages were pretty much black and white: either
the power is on or it's off.

Not so, grasshopper. I stuck my VOM into an outlet and monitored the
line voltage. The reason I did this was that after the power had been
off for a good long time, I heard my microwave squealing a high-pitched
whine. And there was noise coming from the fridge motor. At that point,
I could see that there was about 60 volts on the line, enough so that
when I turned the lights on, they came on, sorta dimly.

After that, the line voltage fluctuated wildly, going from a low of
about 45 volts all the way above 80. My guess is that they (the power
co.) were switching things in and out, and that was causing the ups and
downs. Another unusual thing I noticed was that my neighbor's diesel
generator kicked in when the power went out (they have a small server
farm they like to keep alive). But every time the voltage went above 80
volts, the thing would turn itself off--which meant that they were
running on low voltage for at least part of the time.

I found out that my TV (old analog) and DTV converter work fine on about
75 volts. I didn't want to find out about my computah, so I turned it
off. Also turned off the fridge because I didn't like the sounds I heard
coming from the compressor.

--
Made From Pears: Pretty good chance that the product is at least
mostly pears.
Made With Pears: Pretty good chance that pears will be detectable in
the product.
Contains Pears: �One pear seed per multiple tons of product.

(with apologies to Dorothy L. Sayers)

the on off on off on off was a power company circuit breaker trying to
reset. most will try 3 times then quit and in newer areas report back
tripped

i keep my satellite receivers on a UPS to protect them. undervoltage
is espically bad

In article m, David Nebenzahl wrote:

And really, how else could a transformer fail spectacularly, other than
an overload, except by there being some kind of massive overvoltage
surge (what people incorrectly call a "power surge")?

Actually, transformer cores do "wear out". And when then do,
they do overheat which can lead to spontaneous fire/explosion.

However, if multiple transformers failed in the same area
there was clearly some precipitating event. Most likely
a lighting strike but there are many other potential causes.

Fortunately, it's rare to experience the kinds of fluctuating
voltages you observed. The system is generally designed to
deliver a relatively clean supply or none at all. And it
does work that way most of time.

--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
| Gary Player. |
| http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~

On 3/29/2009 5:34 PM Malcolm Hoar spake thus:

In article m,
David Nebenzahl wrote:

And really, how else could a transformer fail spectacularly, other
than an overload, except by there being some kind of massive
overvoltage surge (what people incorrectly call a "power surge")?

Actually, transformer cores do "wear out". And when then do,
they do overheat which can lead to spontaneous fire/explosion.

However, if multiple transformers failed in the same area
there was clearly some precipitating event. Most likely
a lighting strike but there are many other potential causes.

Absolutely clear weather all around. So it must have been some kind of
cascading failure, and once again, I say the only way transformers can
blow up under such circumstances has to be overvoltage.

Fortunately, it's rare to experience the kinds of fluctuating
voltages you observed. The system is generally designed to
deliver a relatively clean supply or none at all. And it
does work that way most of time.

And how do you know this for sure? Have you monitored your line voltage
during an outage? Could yield some interesting results ...


--
Made From Pears: Pretty good chance that the product is at least
mostly pears.
Made With Pears: Pretty good chance that pears will be detectable in
the product.
Contains Pears: One pear seed per multiple tons of product.

(with apologies to Dorothy L. Sayers)

In article m, David Nebenzahl wrote:
And how do you know this for sure? Have you monitored your line voltage
during an outage? Could yield some interesting results ...

Yes, at various times in the past I have done main voltage
monitoring professionally.

I don't do that now but the computer into which I am typing this
post is connected via a UPS that does record most mains voltage
variations -- sags, surges, spikes, outages, over-under voltage
and more.

And I too am in PG&E land -- not many miles south of Oakland.

--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
| Gary Player. |
| http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~

Actually, transformer cores do "wear out".


Care to elaborate?

Mark

In article , wrote:

Actually, transformer cores do "wear out".

Care to elaborate?

These large capacity transformers typically last 10-30
years and fail for many reasons (other than overload).
Some of the issues:

* Ingress of air and water. This changes the dielectric
properties of the core and can, of course, lead to
corrosion problems.

* Problems related to the coolant (typically oil). The
oil can break down, there can be ionization, production
of gasses and more.

* Laminated cores can delaminate.

* Insulation can break down over time.

* The magnetic properties of the core change over time
making the transformer less efficient leading to the
production of more heat.

Often what starts out as a minor problem creates a hot
spot within the core. This deteriorates further leading
to a more catastrophic (and spectacular) failure of the
device.



--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
| Gary Player. |
| http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~

Actually, transformer cores do "wear out".

Care to elaborate?

These large capacity transformers typically last 10-30
years and fail for many reasons (other than overload).
Some of the issues:

* Ingress of air and water. This changes the dielectric
* properties of the core and can, of course, lead to
* corrosion problems.

* Problems related to the coolant (typically oil). The
* oil can break down, there can be ionization, production
* of gasses and more.

* Laminated cores can delaminate.

* Insulation can break down over time.

* The magnetic properties of the core change over time
* making the transformer less efficient leading to the
* production of more heat.

Often what starts out as a minor problem creates a hot
spot within the core. This deteriorates further leading
to a more catastrophic (and spectacular) failure of the
device.

--


well ok,,,

those certainly are failure mechanisms, but I wouldn't call them "wear
out" ,,, but that's just me...

Mark

On Mar 29, 10:14*pm, wrote:
Actually, transformer cores do "wear out".

Care to elaborate?

Mark

We've had transformers blow up around here. The last one was sort of
interesting. Half the lights went out and the other half stayed on --
it just dropped one leg. It lasted like that for about an hour.
Then ... BOOM ... and it all heck broke loose. It took off a tree
limb that was probably touching it, blew the wires off the pole,
shorted the line causing another transformer to fail. Then the relay
or fuse at the substation tripped and the lights went out in the
entire city.

"David Nebenzahl" wrote in message
s.com...
On 3/29/2009 5:34 PM Malcolm Hoar spake thus:

In article m,
David Nebenzahl wrote:

And really, how else could a transformer fail spectacularly, other
than an overload, except by there being some kind of massive
overvoltage surge (what people incorrectly call a "power surge")?

Slightly OT - The transformer serving my house, about 40' away, was struck
by lightning a few years ago. The noise of the lightning/explosion was
breathtaking. After the storm let up I went out to see what happened. The
pole was splintered and the largest piece of transformer was about 1/2 sq.
foot, and was in the nearby woods. Lotsa oil too. WOW!

David Nebenzahl wrote:
On 3/29/2009 5:34 PM Malcolm Hoar spake thus:

In article m,
David Nebenzahl wrote:

And really, how else could a transformer fail spectacularly, other
than an overload, except by there being some kind of massive
overvoltage surge (what people incorrectly call a "power surge")?

Actually, transformer cores do "wear out". And when then do,
they do overheat which can lead to spontaneous fire/explosion.

However, if multiple transformers failed in the same area
there was clearly some precipitating event. Most likely
a lighting strike but there are many other potential causes.

Absolutely clear weather all around. So it must have been some kind of
cascading failure, and once again, I say the only way transformers can
blow up under such circumstances has to be overvoltage.


The cans are filled with oil acting as a coolant. If the can leaks, and the
transformer's under full load, it will melt, igniting the remaining oil, and
blow that sucker into the bay!

Or it could be part of the plan concerning the candlelight vigil for the
dear departed, Lovelle Mixon. The man had "Love" in his name and was lifted
into the arms of baby Jesus just this past week.

HeyBub wrote:
David Nebenzahl wrote:
On 3/29/2009 5:34 PM Malcolm Hoar spake thus:

In article m,
David Nebenzahl wrote:

And really, how else could a transformer fail spectacularly, other
than an overload, except by there being some kind of massive
overvoltage surge (what people incorrectly call a "power surge")?
Actually, transformer cores do "wear out". And when then do,
they do overheat which can lead to spontaneous fire/explosion.

However, if multiple transformers failed in the same area
there was clearly some precipitating event. Most likely
a lighting strike but there are many other potential causes.
Absolutely clear weather all around. So it must have been some kind of
cascading failure, and once again, I say the only way transformers can
blow up under such circumstances has to be overvoltage.


The cans are filled with oil acting as a coolant. If the can leaks, and the
transformer's under full load, it will melt, igniting the remaining oil, and
blow that sucker into the bay!

Most distribution transformers are air cooled. The ones that are oil
cooled use non-flammable oil. Currently silicone oil and previously PCBs.


Or it could be part of the plan concerning the candlelight vigil for the
dear departed, Lovelle Mixon. The man had "Love" in his name and was lifted
into the arms of baby Jesus just this past week.

On Mar 29, 9:55*pm, David Nebenzahl wrote:
The other night our power went out here in Oakland. Was watching teevee
when the lights went out all of a sudden. Then they came back on. Then
they flickered a bit and went out again. Came on again, there was a
muffled "BOOM!", whereupon they went out, this time for good.

It was the first power outage we'd had here in a long time. And I
noticed some really strange things.

First of all, the "BOOM!" turned out to be a transformer which exploded
rather spectacularly right outside the building I'm in. Some neighbors
down the street said they actually saw the thing go, sparks and all.

Turns out there were several other transformers all over town that blew
at (about) the same time. Power was out to 4,500 customers at the peak
of the outage, in an area covering many square miles. But walking
around, I'd see blocks on end without power and with no streetlights.
Then there'd be a block with power. And some of the blacked-out areas
had working streetlights. The local power grid must be a crazy quilt of
wiring.

Regarding the cause of the outage, when I got ahold of PG&E (Pure Greed
and Extortion), the guy said it was due to "equipment failure". Talking
with my neighbor, though, he said he though it was human error: someone
threw the wrong switch or something.

And really, how else could a transformer fail spectacularly, other than
an overload, except by there being some kind of massive overvoltage
surge (what people incorrectly call a "power surge")?

OK, so for the rest of the evening we were without lights. Sort of.

Sort of? I though power outages were pretty much black and white: either
the power is on or it's off.

Not so, grasshopper. I stuck my VOM into an outlet and monitored the
line voltage. The reason I did this was that after the power had been
off for a good long time, I heard my microwave squealing a high-pitched
whine. And there was noise coming from the fridge motor. At that point,
I could see that there was about 60 volts on the line, enough so that
when I turned the lights on, they came on, sorta dimly.

After that, the line voltage fluctuated wildly, going from a low of
about 45 volts all the way above 80. My guess is that they (the power
co.) were switching things in and out, and that was causing the ups and
downs. Another unusual thing I noticed was that my neighbor's diesel
generator kicked in when the power went out (they have a small server
farm they like to keep alive). But every time the voltage went above 80
volts, the thing would turn itself off--which meant that they were
running on low voltage for at least part of the time.

I found out that my TV (old analog) and DTV converter work fine on about
75 volts. I didn't want to find out about my computah, so I turned it
off. Also turned off the fridge because I didn't like the sounds I heard
coming from the compressor.

--
Made From Pears: Pretty good chance that the product is at least
mostly pears.
Made With Pears: Pretty good chance that pears will be detectable in
the product.
Contains Pears: *One pear seed per multiple tons of product.

(with apologies to Dorothy L. Sayers)

When I lived in Ga there was a small substation, a subsub station if
you will behind the place I worked. This substation fed an industrial
park and quite a large residential area.When lightning hit one of the
transformers there it blew and so did one of the transformers that fed
where I worked, we had three for three phase power. Power was out in a
patchwork all over the residential area and 3 or four other
transformers also blew up scattered around the subdivision. On one
road in particular you could tell that every third street off the road
was without power.




Jimmie

In m, David Nebenzahl
wrote:

The other night our power went out here in Oakland. Was watching teevee
when the lights went out all of a sudden. Then they came back on. Then
they flickered a bit and went out again. Came on again, there was a
muffled "BOOM!", whereupon they went out, this time for good.

It was the first power outage we'd had here in a long time. And I
noticed some really strange things.

First of all, the "BOOM!" turned out to be a transformer which exploded
rather spectacularly right outside the building I'm in. Some neighbors
down the street said they actually saw the thing go, sparks and all.

Turns out there were several other transformers all over town that blew
at (about) the same time. Power was out to 4,500 customers at the peak
of the outage, in an area covering many square miles. But walking
around, I'd see blocks on end without power and with no streetlights.
Then there'd be a block with power. And some of the blacked-out areas
had working streetlights. The local power grid must be a crazy quilt of
wiring.

Regarding the cause of the outage, when I got ahold of PG&E (Pure Greed
and Extortion), the guy said it was due to "equipment failure". Talking
with my neighbor, though, he said he though it was human error: someone
threw the wrong switch or something.

And really, how else could a transformer fail spectacularly, other than
an overload, except by there being some kind of massive overvoltage
surge (what people incorrectly call a "power surge")?

OK, so for the rest of the evening we were without lights. Sort of.

Sort of? I though power outages were pretty much black and white: either
the power is on or it's off.

Not so, grasshopper. I stuck my VOM into an outlet and monitored the
line voltage. The reason I did this was that after the power had been
off for a good long time, I heard my microwave squealing a high-pitched
whine. And there was noise coming from the fridge motor. At that point,
I could see that there was about 60 volts on the line, enough so that
when I turned the lights on, they came on, sorta dimly.

After that, the line voltage fluctuated wildly, going from a low of
about 45 volts all the way above 80.

SNIP

I do remember one power outage (of many) at my workplace where some
strange noises emanated, and the only incandescent light at the workplace
glowed to an extent typical of about 16 volts. I had a voltmeter handy
and it indicated about 40 volts. So I suspect a bunch of noise from UPS
units and a few generators, plus maybe a bit of RF pickup from the many
nearby radio transmitters. This was in the University City section of
Philadelphia, in an urban zip code (19144) having 4 hospitals for people
and 1 for animals.

That power outage did not damage anything.

A few or several months before that was the power "outage" where for the
first 45 minutes or hour or so (I disclaim accurate memory of amount of
time of the following stressful condition), the voltage was about 45
volts. I did not have a voltmeter handy. The only incandescent lamp at
the shop glowed to an extent that I consider typical of about 45 volts.
The fluorescent fixtures (with electronic ballasts) gave an eerie very dim
glow. Two refrigeration devices had compressor motors being burnt out.
Someone I know suggests that a transformer upstream from my shop
could have a 13,200 volt primary with a 4,600 volt tap, and the 4,600 volt
feeding power got switched to the 13,200 volt primary connection as a
result of an overload.
The overload could be from rich college kids having 42 inch plasma TVs
and refrigerators for beer in most bedrooms and most living rooms and 300
watt halogen torchiere lamps almost everywhere and computers running in
most bedrooms. I say "have the flashlights handy" when the weather gets
warm enough to need air conditioning during the "school year" to remove
the heat produced by all those beer cooling refrigerators, 42 inch plasma
TVs and 300 watt halogen lamps that my workplace's neighbors have!

Also turned off the fridge because I didn't like the sounds I heard
coming from the compressor.

- Don Klipstein )

On 3/30/2009 9:02 PM Don Klipstein spake thus:

The overload could be from rich college kids having 42 inch plasma TVs
and refrigerators for beer in most bedrooms and most living rooms and 300
watt halogen torchiere lamps almost everywhere and computers running in
most bedrooms. I say "have the flashlights handy" when the weather gets
warm enough to need air conditioning during the "school year" to remove
the heat produced by all those beer cooling refrigerators, 42 inch plasma
TVs and 300 watt halogen lamps that my workplace's neighbors have!

Not a great example: TVs don't use that much juice, nor do computers.
300-watt torchieres could add up to something significant pretty quickly
(my term for those lamps is "firestarters").

I probably use more power than your neighbors, as I have an electric
water heater (small one, 20 gal.) and an electric dryer. (But no air
conditioner, thank you.)


--
Made From Pears: Pretty good chance that the product is at least
mostly pears.
Made With Pears: Pretty good chance that pears will be detectable in
the product.
Contains Pears: One pear seed per multiple tons of product.

(with apologies to Dorothy L. Sayers)

David Nebenzahl wrote:
On 3/30/2009 9:02 PM Don Klipstein spake thus:

The overload could be from rich college kids having 42 inch plasma
TVs and refrigerators for beer in most bedrooms and most living rooms
and 300 watt halogen torchiere lamps almost everywhere and computers
running in most bedrooms. I say "have the flashlights handy" when the
weather gets warm enough to need air conditioning during the "school
year" to remove the heat produced by all those beer cooling
refrigerators, 42 inch plasma TVs and 300 watt halogen lamps that my
workplace's neighbors have!

Not a great example: TVs don't use that much juice, nor do computers.
300-watt torchieres could add up to something significant pretty quickly
(my term for those lamps is "firestarters").

I probably use more power than your neighbors, as I have an electric
water heater (small one, 20 gal.) and an electric dryer. (But no air
conditioner, thank you.)



There is something that a lot of folks don't realize as
having detrimental effects on the power grid and the
power distribution of homes and business. This has developed
under our noses and most people never considered it.
Asymmetrical loads from switching power supplies can damage
older power transformers that were not designed to handle
the harmonics produced by modern electronic equipment. It's
hard to explain it to a lot of electricians because many of
them have no electronics background. I found a link to a
site with a lot of good information on the problem.

http://tinyurl.com/cn4gv8

TDD

In article ,
wrote:

I know that lcd and crt sets dont use a large amount of power, but
I've heard that the plasma tv sets suck a huge amount of power, and
produce a lot of heat as a result. Being someone who has the tv on
almost all the time, I dont want a plasma type. I read that of the
three, the crt sets use the least power, but the lcd ones are just a
slight increase, unlike the plasma sets that are more like electric
space heaters as far as power usage. For that matter, I have never
understood how a plasma set works anyhow.

For same screen area, CRT uses the most power, plasma uses a little
less, and LCD uses the least. Plasma TVs are big power consumers by
generally being made in larger sizes.

- Don Klipstein )

On Tue, 31 Mar 2009 07:24:12 +0000 (UTC), (Don
Klipstein) wrote:

In article ,
wrote:

I know that lcd and crt sets dont use a large amount of power, but
I've heard that the plasma tv sets suck a huge amount of power, and
produce a lot of heat as a result. Being someone who has the tv on
almost all the time, I dont want a plasma type. I read that of the
three, the crt sets use the least power, but the lcd ones are just a
slight increase, unlike the plasma sets that are more like electric
space heaters as far as power usage. For that matter, I have never
understood how a plasma set works anyhow.

For same screen area, CRT uses the most power, plasma uses a little
less, and LCD uses the least. Plasma TVs are big power consumers by
generally being made in larger sizes.

- Don Klipstein )
The difference between LCD and Plasma is subjective.
AN LSC screen draws constant power while a Plasma draws varying power
depending on the screen contents. Highest draw is all white screen
(means all cells fired) while minimum draw is with black sctreen (no
cells fired).

Actual AVERAGE power use is very similar for equal sized screens - and
something just over half an equivalent CRT.

Remember also, Plasma is 42" and above (perhaps a few 37") while CRT
generally maxes out ar 42" and LCD can go from 2" to 60 or more. So
particularly with Plasma, the power is directly related to size, while
less so with CRT and LCD.