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. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~

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)

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

"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!

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

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.

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 , 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. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~

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.

On Mar 30, 9:51�am, Van Chocstraw
wrote:
bob haller wrote:
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

Some of the high voltage fusible circuit breakers sound like an
explosion and I've seen one set the pole on fire.

--
//--------------------\\
� � � � Van Chocstraw
�\\--------------------//- Hide quoted text -

- Show quoted text -

I actually witnessed a transformer on a pole explode once as i was
driving by. scared the ...... out of me. before cell phone i stopped
at the next pay phone and called it in.

exploded in a ball of fire, from side then flames.

i will ask a retired buddy of mine he was a power lin transformer
engineer designer at one time. he has amusing stories of transformers
failing testing.

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.

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

In article , wrote:

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

I did put the "wear out" in quotation marks.

Having said that, after checking, my use of the phrase does
seem fairly consistent with most dictionary definitions.

1. To make or become unusable through long or heavy use.
2. To use up or consume gradually.
3. To exhaust; tire.

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

In article , wrote:

Having said that, after checking, my use of the phrase does
seem fairly consistent with most dictionary definitions.

1. To make or become unusable through long or heavy use.
2. To use up or consume gradually.
3. To exhaust; tire.

It's usually due to the bearing failure !!!!

Oh right, I guess my tires, shock absorbers, wiper blades,
tooth brush, computer monitor, fence, water heater, etc.
all required repacement because of worn bearings. NOT.

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

In article , wrote:

Oh right, I guess my tires, shock absorbers, wiper blades,
tooth brush, computer monitor, fence, water heater, etc.
all required repacement because of worn bearings. NOT.

Actually, your muffler bearings are the first thing to go on most
cars.

That's a load of balls ;-)

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

On 3/30/2009 2:02 PM spake thus:

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.

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.

I always question what makes them explode. Is it heat buildup, or
internal arcing? The cans they are in, seem like pretty hefty steel.
so it has to take quite a bit to blow them apart.

I've always wanted to see what is actually inside one of them. Is is
similar to the power transformers on electronics, such as the old
power transformers on the old tube tv sets, except bigger and wound
with much thicker wire? I've noticed the transformers inside a
welder are similar too, but that's a much lower voltage.

Yes. All power transformers for low-frequency AC are basically the same:
an iron core of some type with windings around it. Small transformers,
like the ones in audio equipment, TVs, etc., generally use "E"-shaped
cores, with one winding around each outside leg of the "E". Obviously,
the transformers the utilities use are a different configuration. I
don't know what exactly that is: does anyone know what shape they are
inside?

Another thing, what guarantees that the output voltage is correct? Do
thjey contain regulators? I'm sure the high voltage side has voltage
fluctuations, based on usage, loads, and the generation itself.

No regulators: the transformers rely on having the right turns ratio
(ratio of primary to secondary turns) to deliver the correct voltage.


--
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 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 )

In article m, David
Nebenzahl wrote in part:

Yes. All power transformers for low-frequency AC are basically the same:
an iron core of some type with windings around it. Small transformers,
like the ones in audio equipment, TVs, etc., generally use "E"-shaped
cores, with one winding around each outside leg of the "E".

Low frequency power transformers in this power class have "E-I" cores,
with E and I "laminations" alternating/interleaved. The "I pieces" are
adjacent to the 3 tips of the "E pieces". The alternation has E's
sandwiched between I's, and I's sandwiched between E's.

The "center leg" of the "E pieces" has width twice that of the 2 "outer
legs", that of the "backbone of the E", and that of the "I pieces".

Unlike what you said, both the primary and secondary windings are around
the "center leg of the E's".

If an E-I core is used for a transformer requiring some DC in the
primary (such as a "vertical output transformer" of a mostly-tube TV or
output transformer of a single-ended vacuum tube audio amplifier), then
there is likely need for a gap in the core. In that case, the E's are
stacked together pointing the same way, the I's are similarly stacked into
a rectangular block, and some layer of paper or cardboard or whatever is
typically used to space the I's from the E's. The windings are still
around the center leg of the E's.
2-lead fluorescent lamp ballasts (for lamps at most 22 watts in USA) and
"reactor" type ballasts for other lamps and "filter chokes" for some power
supply designs generally have similar E-I core with an "E stack" and an "I
stack" and a gap of some sort.

Lamp ballasts with more than 2 leads (excluding any used by starting
circuitry) and "neon sign transformers" (which are actually ballasts) get
different by using more complex core designs with "magnetic shunts".

- 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)

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 3/30/2009 9:25 PM Don Klipstein spake thus:

In article m, David
Nebenzahl wrote in part:

Yes. All power transformers for low-frequency AC are basically the same:
an iron core of some type with windings around it. Small transformers,
like the ones in audio equipment, TVs, etc., generally use "E"-shaped
cores, with one winding around each outside leg of the "E".

Unlike what you said, both the primary and secondary windings are around
the "center leg of the E's".

Yes. I realized that was wrong after I sent that message.

So do you know the construction details of utility power transformers?


--
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

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.

On Mon, 30 Mar 2009 17:02:57 -0500, wrote:

I've always wanted to see what is actually inside one of them. Is is
similar to the power transformers on electronics, such as the old
power transformers on the old tube tv sets, except bigger and wound
with much thicker wire? I've noticed the transformers inside a
welder are similar too, but that's a much lower voltage.

I saw a recent episode of "How It's Made" and they showed the
construction of a power transformer.

G.S.

wrote:

One other thing. I often notice on poles there are smaller
transformers that have no output cables. They just have two
insulators. The high voltage goes in one side and comes back out the
other. All I can figure is that they are a "choke" to maintain some
sort of regulation.

If it is in series with the high voltage wire it is probably a
"sectionalizer".
Typical pictu
http://www.cooperpower.com/Products/Distribution/Sectionalizers/HydraulicGH.asp

A description of what they do:
http://en.wikipedia.org/wiki/Recloser
I don't think the description is very good - I probably had a better one
in an old thread.

"Sectionalizers" are used with "reclosers". The sectionalizer can be
small because it always opens when there is no current. The recloser is
much larger. There can be many sectionalizers downstream from one recloser.

--
bud--

On Mar 31, 1:57�pm, wrote:
On Tue, 31 Mar 2009 10:15:50 -0600, Gordon Shumway

wrote:
On Mon, 30 Mar 2009 17:02:57 -0500, wrote:

I've always wanted to see what is actually inside one of them. �Is is
similar to the power transformers on electronics, such as the old
power transformers on the old tube tv sets, except bigger and wound
with much thicker wire? � I've noticed the transformers inside a
welder are similar too, but that's a much lower voltage.

I saw a recent episode of "How It's Made" and they showed the
construction of a power transformer.

G.S.

Where was that seen? �I'm assuming something like PBS TV.....

how its made, dirty jobs, air emergency, deconstruction some of my
favorite shows.

all on cable networks...........

bob haller wrote:

On Mar 30, 9:51�am, Van Chocstraw
wrote:

bob haller wrote:

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

Some of the high voltage fusible circuit breakers sound like an
explosion and I've seen one set the pole on fire.

--
//--------------------\\
� � � � Van Chocstraw
�\\--------------------//- Hide quoted text -

- Show quoted text -


I actually witnessed a transformer on a pole explode once as i was
driving by. scared the ...... out of me. before cell phone i stopped
at the next pay phone and called it in.

exploded in a ball of fire, from side then flames.

i will ask a retired buddy of mine he was a power lin transformer
engineer designer at one time. he has amusing stories of transformers
failing testing.

I still remember that summer afternoon in 1985 when a young IRS gal was
sitting in our third floor offices conducting an audit. She had been
there a couple of days and "so far so good". We were getting along fine,
perhaps because in chatting we'd learned that her dad was an alumnus of
the same college I'd graduated from.

Anyway, a window was open next where she was sitting. The skies
darkened, followed shortly by a a crack of lightening and a "boom" as a
pole transformer not far from that open window exploded. The building
lights went out and some sort of alarm started howling.

It was the Devil who made me do it, but I stuck my head out the window,
looked up and yelled, "About twenty feet to the left, God."

(Yes, we passed the audit with flying colors.)


Jeff
--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.

wrote:
On Tue, 31 Mar 2009 00:03:23 GMT, (Malcolm Hoar)
wrote:

In article , wrote:
those certainly are failure mechanisms, but I wouldn't call them "wear
out" ,,, but that's just me...
I did put the "wear out" in quotation marks.

Having said that, after checking, my use of the phrase does
seem fairly consistent with most dictionary definitions.

1. To make or become unusable through long or heavy use.
2. To use up or consume gradually.
3. To exhaust; tire.

It's usually due to the bearing failure !!!!


I'm going to put "Slick 50" in the mains transformer oil!!!

--
PB
"I suspect you're an arrogant little ****ant who grew up in the
Red Bull generation." - CJW

In article , Plague Boy wrote:
wrote:
On Tue, 31 Mar 2009 00:03:23 GMT, (Malcolm Hoar)
wrote:

In article
,
wrote:
those certainly are failure mechanisms, but I wouldn't call them "wear
out" ,,, but that's just me...
I did put the "wear out" in quotation marks.

Having said that, after checking, my use of the phrase does
seem fairly consistent with most dictionary definitions.

1. To make or become unusable through long or heavy use.
2. To use up or consume gradually.
3. To exhaust; tire.

It's usually due to the bearing failure !!!!

I'm going to put "Slick 50" in the mains transformer oil!!!

Trust me, your local utility company puts plenty of additives
into their transformers to prolong their life. Replacing
"worn out" transformers costs them a very considerable sum
of money.

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