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Load Calculation Backup Generator
|
|
| jaywitkow@yahoo.co.uk 2006-05-09, 9:21 pm |
| I'm thinking about buying an 8000W, 240V, portable, backup generator to
connect to my house when the power goes out. This type of generator,
obviously, is designed to be used with extension cords that would be
routed through an open window or door, for example. However, I would
like to connect it directly to the service entrance on the back of my
house. I am aware that this type of connection requires a "transfer
switch".
My question is, do I have to worry about how much of a load I have on
each phase of the generator's output? Or, do I only have to worry about
total wattage?
To clarify, let's take an extreme (and unrealistic) example. Let's say
I have a house that draws 6000W on one phase and 1000W on the other
phase and I connect to the service entrance via the generator's 240V,
30A receptacle. So, in this situation I would be drawing about 50 Amps
on phase 1 and 8 Amps on phase 2, for a total of 7000W.
Just as an example, there is an 8000 W generator at:
http://tinyurl.com/plg7l
There is a schematic (PDF, page 2) for this generator at:
http://tinyurl.com/ra6kr
This schematic shows a "120/240V 30Amp" socket connector protected by a
"30Amp 2P" circuit breaker (CB1). So, I guess I've answered my own
question. It looks to me like a current greater than 30A on either pole
will trip the breaker.
So, it's back to the drawing board and here's where I'm definitely
getting in over my head. Is it possible to parallel the windings
somehow so that the two legs are in phase?
If you could do that then the total output could be connected to both
bus bars in the circuit breaker box. Now in the (hypothetical)
situation where one bus bar draws 6000W and the other draws 1000W,
there wouldn't be a problem.
The disadvantage would be that you couldn't operate any 240V
appliances. However, with these relatively small generators, you
probably wouldn't want to do that anyway. A clothes dryer probably
draws 5000-6000 watts all by itself. You would lose the option to
operate one or two burners on your electric range, but you could use
your microwave oven or your toaster oven instead.
| |
| Vaughn Simon 2006-05-09, 9:21 pm |
|
<jaywitkow@yahoo.co.uk> wrote in message
news:1147217503.427306.28320@y43g2000cwc.googlegroups.com...
> The disadvantage would be that you couldn't operate any 240V
> appliances. However, with these relatively small generators, you
> probably wouldn't want to do that anyway. A clothes dryer probably
> draws 5000-6000 watts all by itself. You would lose the option to
> operate one or two burners on your electric range, but you could use
> your microwave oven or your toaster oven instead.
You are really good at answering your own questions! You are beginning to
understand the tradeoffs involved in a standby power system. If you are willing
to do a little intelligent load management, and perhaps give up a few of your
largest loads entirely, you will do fine.
Now how are you going to fuel this monster?
Vaughn
>
| |
| Pete C. 2006-05-09, 9:21 pm |
| jaywitkow@yahoo.co.uk wrote:
>
> I'm thinking about buying an 8000W, 240V, portable, backup generator to
> connect to my house when the power goes out. This type of generator,
> obviously, is designed to be used with extension cords that would be
> routed through an open window or door, for example. However, I would
> like to connect it directly to the service entrance on the back of my
> house. I am aware that this type of connection requires a "transfer
> switch".
>
> My question is, do I have to worry about how much of a load I have on
> each phase of the generator's output? Or, do I only have to worry about
> total wattage?
>
> To clarify, let's take an extreme (and unrealistic) example. Let's say
> I have a house that draws 6000W on one phase and 1000W on the other
> phase and I connect to the service entrance via the generator's 240V,
> 30A receptacle. So, in this situation I would be drawing about 50 Amps
> on phase 1 and 8 Amps on phase 2, for a total of 7000W.
>
> Just as an example, there is an 8000 W generator at:
>
> http://tinyurl.com/plg7l
>
> There is a schematic (PDF, page 2) for this generator at:
>
> http://tinyurl.com/ra6kr
>
> This schematic shows a "120/240V 30Amp" socket connector protected by a
> "30Amp 2P" circuit breaker (CB1). So, I guess I've answered my own
> question. It looks to me like a current greater than 30A on either pole
> will trip the breaker.
>
> So, it's back to the drawing board and here's where I'm definitely
> getting in over my head. Is it possible to parallel the windings
> somehow so that the two legs are in phase?
>
> If you could do that then the total output could be connected to both
> bus bars in the circuit breaker box. Now in the (hypothetical)
> situation where one bus bar draws 6000W and the other draws 1000W,
> there wouldn't be a problem.
>
> The disadvantage would be that you couldn't operate any 240V
> appliances. However, with these relatively small generators, you
> probably wouldn't want to do that anyway. A clothes dryer probably
> draws 5000-6000 watts all by itself. You would lose the option to
> operate one or two burners on your electric range, but you could use
> your microwave oven or your toaster oven instead.
You've found the wonders of load management. You have a generator that
has much lower capacity than your normal service so you have to
selectively apply loads to stay within it's capacity.
When you have a power failure you turn off all the circuit breakers in
your well labeled (it is well labeled isn't it?) service panel first,
then connect and start your generator and then throw the transfer switch
to provide generator power to the panel. After that you have to actively
manage which circuits you have on.
For instance you probably want to switch on your lighting circuits, but
make sure you don't have an excessive number of lights on. This is your
small baseline load that you'll keep on. This load probably represents
about 5A/leg on your well balanced service panel (it is well balanced
isn't it?).
After your baseline load you have a variety of loads that the generator
can power individually, but not together. Fortunately these loads are
rarely time critical so one can "wait" while another is using the
generator capacity.
Examples are:
Heat or A/C - These loads can easily stand to wait even an hour while
the generator powers other loads.
Refrigerator - A refrigerator can easily go a couple hours (with minimal
opening) without an issue.
Well pump - The pressure tank usually holds at least 20 gal of useable
water so you can wash hands and flush toilets a few times before you
have to provide power to the well pump.
Stove / oven / microwave - Again you can hold off cooking dinner until
the heat or A/C has completed it's cycle and those loads can wait the
hour until dinner is cooked.
Water heater - A 50gal+ well insulated water heater will maintain a
reasonable water temp without power for a good while.
Of course managing these loads takes a bit of work. In really big
installations automated load management is fairly common and there is no
reason that such systems can't be scaled and applied to a residential
sized installation.
Pete C.
| |
|
|
| gfretwell@aol.com 2006-05-09, 11:21 pm |
| On Wed, 10 May 2006 00:00:19 GMT, "Vaughn Simon"
<vaughnsimonHATESSPAM@att.FAKE.net> wrote:
> Now how are you going to fuel this monster?
Exactly how our friends in Punta Gorda Florida (Charlie) referred to
it. "who is going to feed the monster"?
It is not an insignificant amount of fuel either. They were filling up
cans every day.
| |
|
|
<jaywitkow@yahoo.co.uk> wrote in message
news:1147217503.427306.28320@y43g2000cwc.googlegroups.com...
> I'm thinking about buying an 8000W, 240V, portable, backup generator to
> connect to my house when the power goes out. This type of generator,
> obviously, is designed to be used with extension cords that would be
> routed through an open window or door, for example. However, I would
> like to connect it directly to the service entrance on the back of my
> house. I am aware that this type of connection requires a "transfer
> switch".
>
> The disadvantage would be that you couldn't operate any 240V
> appliances. However, with these relatively small generators, you
> probably wouldn't want to do that anyway. A clothes dryer probably
> draws 5000-6000 watts all by itself. You would lose the option to
> operate one or two burners on your electric range, but you could use
> your microwave oven or your toaster oven instead.
>
I have used an 8000W backup generator during power outages for the house for
over 20 years. It was wired into the main panel with a dedicated plug. I
strongly recommend an automatic transfer switch, even though I didn't use
one.
It's really no problem, once you understand your energy "budget." All the
lighting was OK, but we turned off each light as we left the room. The
generator ran the furnace, the freezers, fridge and TV without concern.
Using the microwave, dishwasher or coffeemaker, required a bit of planning,
but worked quite well if you didn't use more than one of them at a time.
We refrained from using the dryer or anything with big electric elements
whenever possible. I suspect we could have used them, by turning other
things off, but the outages were generally short enough that we didn't need
them. The 220V submersible pump in the well was a bit of a concern, but we
could generally assume it wasn't running when no one was using water. You
could also tell a lot by the sound of load on the engine. The general rule
was "one thing at a time, and nothing unnecessary" and everything worked
fine.
I use a 10,000 watt generator now, but the same general rules apply.
| |
| netster403@gmail.com 2006-05-10, 3:21 am |
| BIG WARNING:***************
You MUST rember to shut off the main breaker before the generator is
plugged into the house! If the current from the generator flows
backward into the powercompany's transformer it will be a sight to see!
You may fry a lineman, or blow up the transformer.
Transformers take large voltages and reduce the voltages through
differences in windings. for example power goes from big(1k+ volts) to
small (115v leg's). They also go in reverse, turning small to big if
used improperly!
Be careful!
--Alex
*** end big warning ***
JoeSP wrote:
> <jaywitkow@yahoo.co.uk> wrote in message
> news:1147217503.427306.28320@y43g2000cwc.googlegroups.com...
>
> I have used an 8000W backup generator during power outages for the house for
> over 20 years. It was wired into the main panel with a dedicated plug. I
> strongly recommend an automatic transfer switch, even though I didn't use
> one.
>
> It's really no problem, once you understand your energy "budget." All the
> lighting was OK, but we turned off each light as we left the room. The
> generator ran the furnace, the freezers, fridge and TV without concern.
> Using the microwave, dishwasher or coffeemaker, required a bit of planning,
> but worked quite well if you didn't use more than one of them at a time.
>
> We refrained from using the dryer or anything with big electric elements
> whenever possible. I suspect we could have used them, by turning other
> things off, but the outages were generally short enough that we didn't need
> them. The 220V submersible pump in the well was a bit of a concern, but we
> could generally assume it wasn't running when no one was using water. You
> could also tell a lot by the sound of load on the engine. The general rule
> was "one thing at a time, and nothing unnecessary" and everything worked
> fine.
>
> I use a 10,000 watt generator now, but the same general rules apply.
| |
| Wes Stewart 2006-05-10, 10:21 am |
| On 9 May 2006 22:28:44 -0700, netster403@gmail.com wrote:
>BIG WARNING:***************
>
>You MUST rember to shut off the main breaker before the generator is
>plugged into the house! If the current from the generator flows
>backward into the powercompany's transformer it will be a sight to see!
>You may fry a lineman, or blow up the transformer.
While there is a theoretical issue with safety for a lineman, consider
that if the power outage is widespread and the OP fails to open the
main breaker, he will simply be trying to power the whole grid with
his 8 KW. Talk about "load sharing".
He won't be burning up any power company transformers but his APU
won't be happy. Of course an automatic transfer switch is in order.
| |
| JoeSP 2006-05-10, 10:21 am |
|
"Wes Stewart" <n7ws*@*yahoo.com> wrote in message
news:r7o362dq8ns8adnuvam9orvpgsui2rs9v3@4ax.com...
> On 9 May 2006 22:28:44 -0700, netster403@gmail.com wrote:
>
>
> While there is a theoretical issue with safety for a lineman, consider
> that if the power outage is widespread and the OP fails to open the
> main breaker, he will simply be trying to power the whole grid with
> his 8 KW. Talk about "load sharing".
>
It wasn't very theoretical for the families of these linesmen:
http://www.gulfcoastnews.com/GCNnewsHancockKatrina2.htm
http://www.rv.net/forum/index.cfm/f...sg/15853602.cfm
| |
| Palindr☻me 2006-05-10, 11:21 am |
| JoeSP wrote:
> "Wes Stewart" <n7ws*@*yahoo.com> wrote in message
> news:r7o362dq8ns8adnuvam9orvpgsui2rs9v3@4ax.com...
>
>
>
> It wasn't very theoretical for the families of these linesmen:
>
> http://www.gulfcoastnews.com/GCNnewsHancockKatrina2.htm
>
> http://www.rv.net/forum/index.cfm/f...sg/15853602.cfm
>
>
>
I suspect that the line was down between the house and the local HT
transformer, when the lineman picked it up to reconnect it, assuming it
would be dead....
I've come across one bright spark who wired the generator to a three pin
plug ( yes, with bare pins..) and plugged that in with the house
isolator closed. It tripped out the genny. He re-started the genny and
then went to reclose the genny trip - but, meanwhile, mains supply had
been restored. ..
It just tripped out the genny again.
Genny designers do seem to know what they are doing....
--
Sue
| |
| JoeSP 2006-05-10, 11:21 am |
|
"Palindr?me" <me9@privacy.net> wrote in message
news:1263qc84929f5bc@corp.supernews.com...
> JoeSP wrote:
> I suspect that the line was down between the house and the local HT
> transformer, when the lineman picked it up to reconnect it, assuming it
> would be dead....
>
That's utterly ridiculous. It's a well-known fact that generators can
backfeed through a transformer and re-energize the line. Lines charged with
kilovolts of electricity require very little current to kill someone who
touches it.
> I've come across one bright spark who wired the generator to a three pin
> plug ( yes, with bare pins..) and plugged that in with the house isolator
> closed. It tripped out the genny. He re-started the genny and then went to
> reclose the genny trip - but, meanwhile, mains supply had been restored.
> ..
>
> It just tripped out the genny again.
>
>
> Genny designers do seem to know what they are doing....
>
> --
> Sue
>
>
>
>
>
| |
| Spehro Pefhany 2006-05-10, 11:21 am |
| On Wed, 10 May 2006 13:53:48 GMT, the renowned "JoeSP"
<olegp@telus.net> wrote:
>
>"Palindr?me" <me9@privacy.net> wrote in message
>news:1263qc84929f5bc@corp.supernews.com...
>
>That's utterly ridiculous. It's a well-known fact that generators can
>backfeed through a transformer and re-energize the line. Lines charged with
>kilovolts of electricity require very little current to kill someone who
>touches it.
That's why code in most places requires an approved transfer switch to
be installed. Here's one available at Home Despot:
http://www.homedepot.com/prel80/HDU...e=10-19535279-2
Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
| |
| barry@sme-online.com 2006-05-10, 11:21 am |
| Suspect what you wish. Whether a dirty, sweaty lineman gets hit by 120v
ac or 1200v, under many circumstances she or he'll be just as dead.
So this is not an abstract game.
J
| |
| Palindr☻me 2006-05-10, 12:21 pm |
| JoeSP wrote:
> "Palindr?me" <me9@privacy.net> wrote in message
> news:1263qc84929f5bc@corp.supernews.com...
>
>
>
> That's utterly ridiculous. It's a well-known fact that generators can
> backfeed through a transformer and re-energize the line. Lines charged with
> kilovolts of electricity require very little current to kill someone who
> touches it.
>
Far from being ridulous, it is one possible scenario. And, generally
speaking, the same current is needed to kill someone whether delivered
at 120v or 11kV - assuming a series element that limits the current to
that value.
Don't US linemen either work using live circuit protocols, or tie the
circuits to ground before working on them? The risk of some idiot
energising what should be a dead circuit seems so obvious that I find it
very hard to believe that they don't..
--
Sue
| |
| Michael A. Terrell 2006-05-10, 12:21 pm |
| Palindr?me wrote:
>
> Don't US linemen either work using live circuit protocols, or tie the
> circuits to ground before working on them? The risk of some idiot
> energising what should be a dead circuit seems so obvious that I find it
> very hard to believe that they don't..
>
> --
> Sue
After the hurricanes here in Central Florida they were driving an
area to map out all the downed lines and lines with tree branches stuck
in them in a section. They generally worked by splicing the wires that
were low enough to touch on the supply side poles first, then when it
was safe they energized that section. Finally, they spliced the rest of
the downed lines hot. The crew doing restoration in my area was from
Texas, and didn't have the right kind of fuses for the 7200 volt line
feeding about 100 homes.
They were in fully insulated bucket trucks with HV rated gloves
during all of this. Otherwise they would have had to shut down the
whole area at the substation and do all the repairs which took weeks.
Some power poles with minor damage weren't replaced for over a year.
They had red flags and a job number nailed to them to warn workers that
they were not safe to work on with anything smaller than a line bucket.
I believe we had more fatalities from traffic accidents than
electrocutions. One crew's bucket truck was hit on the highway after
they had finished their work, and they were headed back to their home
state. 
--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.
Michael A. Terrell
Central Florida
| |
| Wes Stewart 2006-05-10, 3:21 pm |
| On Wed, 10 May 2006 13:07:06 GMT, "JoeSP" <olegp@telus.net> wrote:
>
>"Wes Stewart" <n7ws*@*yahoo.com> wrote in message
>news:r7o362dq8ns8adnuvam9orvpgsui2rs9v3@4ax.com...
>
>It wasn't very theoretical for the families of these linesmen:
>
>http://www.gulfcoastnews.com/GCNnewsHancockKatrina2.htm
>
>http://www.rv.net/forum/index.cfm/f...sg/15853602.cfm
Zero facts in those references:
I didn't mean to infer that backfeed isn't an issue, I was only
pointing out the nonsense about blowing up transformers, etc.
You also removed the last line in my post where I clearly stated that
a transfer switch was called for.
I stand by my statement that if the whole grid is down, an 8 KW
generator isn't going to energize it or blow anything up.
This reference says about the same thing:
http://www.lineman.com/about_articles4.cfm
"...The hazard of generator back feed seems to be greatest when
lineworkers are working on a single transformer or a small section of
line. "Portable generators and motors are usually not powerful enough
to supply large utility loads, and the voltage will tend to collapse
under those circumstances," explains Drew...."
They go on to say the obvious, "Always consider the possibility of
back feed when working on de-energized lines, and consider from which
direction the power could flow. "This should be discussed during each
job briefing session," Drew emphasizes...."
| |
|
|
"Palindr?me" <me9@privacy.net> wrote in message
news:1263uj968rr7n76@corp.supernews.com...
> JoeSP wrote:
>
> Far from being ridulous, it is one possible scenario. And, generally
> speaking, the same current is needed to kill someone whether delivered at
> 120v or 11kV - assuming a series element that limits the current to that
> value.
>
>
> Don't US linemen either work using live circuit protocols, or tie the
> circuits to ground before working on them? The risk of some idiot
> energising what should be a dead circuit seems so obvious that I find it
> very hard to believe that they don't..
>
>
> --
> Sue
Anything to win an argument? Even something so stupid as not having to worry
about your generator backfeeding through the lines?
| |
| Rich Grise 2006-05-10, 5:21 pm |
| On Tue, 09 May 2006 16:31:43 -0700, jaywitkow wrote:
> I'm thinking about buying an 8000W, 240V, portable, backup generator to
....
> Just as an example, there is an 8000 W generator at:
>
> http://tinyurl.com/plg7l
>
> There is a schematic (PDF, page 2) for this generator at:
>
> http://tinyurl.com/ra6kr
>
> This schematic shows a "120/240V 30Amp" socket connector protected by a
> "30Amp 2P" circuit breaker (CB1). So, I guess I've answered my own
> question. It looks to me like a current greater than 30A on either pole
> will trip the breaker.
....
So, what you need to do is "load balance": inspect the house wiring, and
find out just what the load actually is on each leg. (with USA 240VCT,
they're not phases, they're legs, since there is nothing to shift the
phase, it's only a center-tapped 240V).
If the house was wired by competent people, most of this should already
have been taken care of, since the power company likes balanced loads too.
If you need to run the toaster oven and space heater simultaneously, for
example, plug one into leg "A" (black/white) and the other into leg "B"
(red/white). These can even both be on a duplex outlet, if you break the
shorting tab.
Or, you could go full-goose bozo, and buy all 240V appliances. ;-)
And, just FYI, the power company should be very helpful with the crossover
switch issue.
Have Fun!
Rich
| |
|
| In article <1263uj968rr7n76@corp.supernews.com>,
Palindr?me <me9@privacy.net> wrote:
> Far from being ridulous, it is one possible scenario. And, generally
> speaking, the same current is needed to kill someone whether delivered
> at 120v or 11kV - assuming a series element that limits the current to
> that value.
>
>
> Don't US linemen either work using live circuit protocols, or tie the
> circuits to ground before working on them? The risk of some idiot
> energising what should be a dead circuit seems so obvious that I find it
> very hard to believe that they don't..
>
>
> --
> Sue
In the US, Linemen DO follow HOT LINE Protocol when working with ALL
Repair type operations. That being Said, when they first come to a
WorkSite, dealing with downed lines is a BIG DEAL, and having some
DUFUS, backfeeding the grid with his toy genset, is a BIG Concern,
and it happens much more often that anyone suspects.
Me been there, had to deal with that......
| |
| Bruce in Alaska 2006-05-10, 7:21 pm |
| In article <n2a8g.43665$Fs1.16724@bgtnsc05-news.ops.worldnet.att.net>,
"Vaughn Simon" <vaughnsimonHATESSPAM@att.FAKE.net> wrote:
> <jaywitkow@yahoo.co.uk> wrote in message
> news:1147217503.427306.28320@y43g2000cwc.googlegroups.com...
>
> You are really good at answering your own questions! You are beginning
> to
> understand the tradeoffs involved in a standby power system. If you are
> willing
> to do a little intelligent load management, and perhaps give up a few of your
> largest loads entirely, you will do fine.
>
> Now how are you going to fuel this monster?
>
> Vaughn
>
>
>
The thing to remember is that your Genset when in 120/240Vac mode can
only supply 1/2 the total load amperage to each leg. So if you have
a 6Kw genset then only 3Kw per leg can be supplied without overcurrenting
that sator winding. For figuring sake, you can probubly allow an extra
10% to that if you have good airflow thru the generator core, but even
that maybe iffy. If you were to use a Transfer switch, have a 120Vac
only mode on the genend, and wire the two 120Vac legs together on the
Genset side of the transfer switch, then you could use all 6Kw @120Vac,
but none of your 240Vac Loads would operate. Most of the 240Vac Loads
wouldn't really be nessesary in Emergency Powered situations anyway.
Bruce in alaska
--
add a <2> before @
| |
| Vaughn Simon 2006-05-10, 8:21 pm |
|
"Bruce in Alaska" <bruceg@btpost.net> wrote in message
news:bruceg-7E8554.14172810052006@netnews.worldnet.att.net...
> In article <n2a8g.43665$Fs1.16724@bgtnsc05-news.ops.worldnet.att.net>,
> The thing to remember is that your Genset when in 120/240Vac mode can
> only supply 1/2 the total load amperage to each leg. So if you have
> a 6Kw genset then only 3Kw per leg can be supplied without overcurrenting
> that sator winding. For figuring sake, you can probubly allow an extra
> 10% to that if you have good airflow thru the generator core, but even
> that maybe iffy. If you were to use a Transfer switch, have a 120Vac
> only mode on the genend, and wire the two 120Vac legs together on the
> Genset side of the transfer switch, then you could use all 6Kw @120Vac,
> but none of your 240Vac Loads would operate. Most of the 240Vac Loads
> wouldn't really be nessesary in Emergency Powered situations anyway.
I don't talk about it much because few people would understand, so
therefore many would assume I was doing something dangerous, or immoral, or
unpatriotic... but that is exactly the way my CCK has been wired since the
beginning. It is one of the ways that we survive just fine on 4KW (or even
less when the Onan fails us).
Vaughn
| |
| Palindr☻me 2006-05-10, 9:21 pm |
| Me wrote:
> In article <1263uj968rr7n76@corp.supernews.com>,
> Palindr?me <me9@privacy.net> wrote:
>
>
>
>
> In the US, Linemen DO follow HOT LINE Protocol when working with ALL
> Repair type operations. That being Said, when they first come to a
> WorkSite, dealing with downed lines is a BIG DEAL, and having some
> DUFUS, backfeeding the grid with his toy genset, is a BIG Concern,
> and it happens much more often that anyone suspects.
>
> Me been there, had to deal with that......
As long as any idiot can just buy a genny over the counter, then there
are going to be backfeeds. When it comes to "how often anyone suspects",
in my case I suspect that it is pretty common.
That's why I did find it a little suprising that linemen have been
injured/killed by such backfeeding, unless they weren't following SOP. I
could just about imagine it happening with lv lines, eg the line from
local transformer to the house. But I couldn't imagine an engineer
working with an hv line taking short cuts. You don't get a second chance
with 11kV, or whatever equivalent voltage you use.
It is not just toy gensets that are available - my local toolhire shop
will quite happily let anyone hire a 20kVA baby and tow it home...
http://www.hss.com/g/41520/Generato...lenced__Bt.html
--
Sue
| |
| Solar Flare 2006-05-10, 11:21 pm |
| There are always idiot linesmen out there as well as idiot generator
installers.
Yes, they have a protocol that insures safe handling but many are not
the sharpest knives in the drawer either and using the procedures can
take away from their macho manhood sometimes.
"Palindr?me" <me9@privacy.net> wrote in message
news:1263uj968rr7n76@corp.supernews.com...
> JoeSP wrote:
>
> Far from being ridulous, it is one possible scenario. And,
> generally speaking, the same current is needed to kill someone
> whether delivered at 120v or 11kV - assuming a series element that
> limits the current to that value.
>
>
> Don't US linemen either work using live circuit protocols, or tie
> the circuits to ground before working on them? The risk of some
> idiot energising what should be a dead circuit seems so obvious that
> I find it very hard to believe that they don't..
>
>
> --
> Sue
>
>
>
| |
| Solar Flare 2006-05-10, 11:21 pm |
| Was that before or after you astronaut programme employment?
"Me" <Me@shadow.orgs> wrote in message
news:Me-B943E8.14080210052006@netnews.worldnet.att.net...
>
> In the US, Linemen DO follow HOT LINE Protocol when working with ALL
> Repair type operations. That being Said, when they first come to a
> WorkSite, dealing with downed lines is a BIG DEAL, and having some
> DUFUS, backfeeding the grid with his toy genset, is a BIG Concern,
> and it happens much more often that anyone suspects.
>
> Me been there, had to deal with that......
| |
| Thomas D. Horne, FF EMT 2006-05-11, 1:21 am |
| Bruce in Alaska wrote:
> In article <n2a8g.43665$Fs1.16724@bgtnsc05-news.ops.worldnet.att.net>,
> "Vaughn Simon" <vaughnsimonHATESSPAM@att.FAKE.net> wrote:
>
>
> The thing to remember is that your Genset when in 120/240Vac mode can
> only supply 1/2 the total load amperage to each leg. So if you have
> a 6Kw genset then only 3Kw per leg can be supplied without overcurrenting
> that sator winding. For figuring sake, you can probubly allow an extra
> 10% to that if you have good airflow thru the generator core, but even
> that maybe iffy. If you were to use a Transfer switch, have a 120Vac
> only mode on the genend, and wire the two 120Vac legs together on the
> Genset side of the transfer switch, then you could use all 6Kw @120Vac,
> but none of your 240Vac Loads would operate. Most of the 240Vac Loads
> wouldn't really be nessesary in Emergency Powered situations anyway.
>
> Bruce in alaska
Bruce
In most homes in the US and Canada what you suggest can lead to circuit
failure and fire. Most homes contain at least one multiwire branch
circuit. In order for the neutral of such a circuit to not overheat and
fault out there must be a voltage between each ungrounded conductor and
the grounded neutral conductor and a voltage between the ungrounded
conductors. When a generator is fed into a homes wiring using a bootleg
Edison rather than a true Edison circuit the voltage between the two
separate ungrounded current carrying conductors is zero so the current
on the shared grounded current carrying neutral conductors is the sum of
the current on the two ungrounded current carrying conductors that it
serves. In the real Edison Circuit arrangement the the current in the
grounded current carrying neutral conductors is only the difference in
the current flow of the ungrounded conductors of the multi wire branch
circuit.
--
Tom Horne
--
Tom Horne
Well we aren't no thin blue heroes and yet we aren't no blackguards to.
We're just working men and woman most remarkable like you.
| |
| Tzortzakakis Dimitrios 2006-05-11, 2:21 pm |
|
Ï "Solar Flare" <solfart@hotomale.invalid> Ýãñáøå óôï ìÞíõìá
news:-d-dncAi-PrsCv_ZRVn-pQ@golden.net...
> Was that before or after you astronaut programme employment?
>
> "Me" <Me@shadow.orgs> wrote in message
> news:Me-B943E8.14080210052006@netnews.worldnet.att.net...
>
>
In HV (V>=66 kV in Europe) they use grounding switches, besides opening
breaker and disconnect switches, that connect each leg to the ground not
only of accidental breaker closing but also induced voltage of parallel
lines.I have also seen a voltage tester for MV when some linemen did
something in MV in my neighborhood.Normally in MV (V>=15 kV<=25kV)you have
to test and then connect together all phases and to ground, I don't know how
exactly they do it.But in Kozani (where the brown coal is, 70% of Greece's
electricity is generated there)terrible accidents have happened.Some poor
lad opened the 20 kV bus bars cabinet and all they found of him was his
shoes.Some other touched an energized 150 kV wire and he was zapped like a
mosquitoe.
--
Tzortzakakis Dimitrios
major in electrical engineering,freelance electrician
542nd mechanized infantry batallion
dimtzort AT otenet DOT gr
| |
| Tony Wesley 2006-05-11, 6:21 pm |
|
Palindr=E2=98=BBme wrote:
> As long as any idiot can just buy a genny over the counter, then there
> are going to be backfeeds. When it comes to "how often anyone suspects",
> in my case I suspect that it is pretty common.
>
> That's why I did find it a little suprising that linemen have been
> injured/killed by such backfeeding, unless they weren't following SOP. [=
snip]
When the crew is working 16-hour days for multiple days, I suspect that
SOP is occasionally not followed, either as intentionalal short cut or
more likely, just from being tired.
| |
| jaywitkow@yahoo.co.uk 2006-05-13, 12:21 am |
| Rich Grise wrote:
> ...
>
> So, what you need to do is "load balance": inspect the house wiring, and
> find out just what the load actually is on each leg. (with USA 240VCT,
> they're not phases, they're legs, since there is nothing to shift the
> phase, it's only a center-tapped 240V).
.. . .
> Have Fun!
> Rich
Well, I have done a lot of work on this since my original post. First
of all, I did an audit of all the breakers and found out where they go
and what leg they are on. With a little research, I found that with the
older, larger-sized breakers, the legs alternate with every breaker.
With the new, smaller-sized breakers, they also alternate, but there
are two breakers in a single package that is the size of one of the old
breakers.
After assigning the leg number to each breaker, I spot checked my
results with a volt-meter by checking a number of outlets. If you get a
240V reading, then obviously, the meter is connected to opposite legs.
Then I also did some math for load management. It turns out that I am
very lucky. The load balancing is very good just like it is. I was
prepared, though, to rewire some of the breakers if I had to. This
wouldn't be very difficult.
Then I got lucky again and found a used Briggs & Stratton, Wheelhouse
5,550W at a local pawn shop for $389.95. It looks new and runs perfect
and I checked the voltages with a test load (electric heater). This
saved me about $800-$900 because I was going to buy a new 8000W
generator.
Now I have a new problem. This thing is very noisy! The first thing
I'm going to try is installing an automobile muffler on it.
Unfortunately, though, the flange and pipe and muffler are all one
piece and I don't want to destroy the muffler by cutting the pipe.
However, it looks like I got lucky again. I found a seller on ebay that
is selling Briggs & Stratton flanges that will fit my engine. So, I'm
going to give the automobile muffler option a try.
If that doesn't work, there's a website that shows a method of
enclosing this kind of generator in multiple boxes. If I have to, I
guess I'll do that. That website, by the way, is at:
http://soundproofing.org/infopages/generator.htm
| |
| Vaughn Simon 2006-05-13, 9:21 am |
|
<jaywitkow@yahoo.co.uk> wrote in message
news:1147488797.795846.303280@y43g2000cwc.googlegroups.com...
> Rich Grise wrote:
>
> Then I also did some math for load management. It turns out that I am
> very lucky. The load balancing is very good just like it is. I was
> prepared, though, to rewire some of the breakers if I had to. This
> wouldn't be very difficult.
Good job!
> Now I have a new problem. This thing is very noisy!
Yep, I think we told you about that.
>The first thing
> I'm going to try is installing an automobile muffler on it.
> Unfortunately, though, the flange and pipe and muffler are all one
> piece and I don't want to destroy the muffler by cutting the pipe.
> However, it looks like I got lucky again. I found a seller on ebay that
> is selling Briggs & Stratton flanges that will fit my engine. So, I'm
> going to give the automobile muffler option a try.
Be sure to have a flexible connection connection between the muffler and
the flange. Otherwise you will break the flange or the bolts that connect it to
the engine. Of course, the muffler can only reduce the exhaust note; there is
other noise...
>
> If that doesn't work, there's a website that shows a method of
> enclosing this kind of generator in multiple boxes. If I have to, I
> guess I'll do that. That website, by the way, is at:
> http://soundproofing.org/infopages/generator.htm
Someone mentioned sandbags. Those coupled with (perhaps) a hedge sounds
like a useable idea. Or perhaps concrete blocks stacked and filled with sand?
I use Home Depot wooden fence. I nailed an extra layer of wooden pickets on it
to make it double thick, and sealed it at the bottom so the noise can only
escape at a high angle. Whatever you do, don't forget that cooling air must
somehow get in and exhaust & hot air must somehow get out.
Vaughn
>
| |
|
|
| jaywitkow@yahoo.co.uk 2006-05-13, 1:21 pm |
| Vaughn Simon wrote:
> <jaywitkow@yahoo.co.uk> wrote in message
> news:1147488797.795846.303280@y43g2000cwc.googlegroups.com...
>
> Someone mentioned sandbags. Those coupled with (perhaps) a hedge sounds
> like a useable idea. Or perhaps concrete blocks stacked and filled with sand?
> I use Home Depot wooden fence. I nailed an extra layer of wooden pickets on it
> to make it double thick, and sealed it at the bottom so the noise can only
> escape at a high angle. Whatever you do, don't forget that cooling air must
> somehow get in and exhaust & hot air must somehow get out.
>
> Vaughn
>
Sandbags?! That's an interesting idea. In doing some searching on
Google, it looks like the drawback is that they rot with time. Dayton
Bag & Burlap (http://daybag.com/industrial/sand_bags.html) has some
special "CIA 12BB" bags that last "up to 3-5 years". My guess is that
if I put a roof over them, they could last a lot longer than that.
Coincidentally, I have a rather large, 25-year-old sandpile that I
would like to remove and cleanup. So, I could kill two birds with one
stone.
I could, perhaps, build a small roof that would lay on top of the bags.
Maybe I could make it out of heavy particle board and roll roofing.
That would look better than simply throwing a sheet of plastic over the
"bunker" to protect the bags from the sun. That might also provide some
additional sound proofing. If I did that, I would still have the
problem of sound proofing the open entrance that I would need to wheel
the generator in and out of, though.
Nothing comes to mind at the moment for the entrance. So, I'll have to
do some thinking about that. I suppose I could make an L-shaped
entrance so that the sound would have to go around a corner to get out
.. . ."
| |
| Rich Grise 2006-05-13, 4:21 pm |
| On Sat, 13 May 2006 08:34:00 -0700, jaywitkow wrote:
>
> Sandbags?! That's an interesting idea. In doing some searching on
> Google, it looks like the drawback is that they rot with time. Dayton
> Bag & Burlap (http://daybag.com/industrial/sand_bags.html) has some
> special "CIA 12BB" bags that last "up to 3-5 years". My guess is that
> if I put a roof over them, they could last a lot longer than that.
Aren't they made of plastic these days? If a poly or nylon or kevlar
bag rots in only a few years, why are they all worried about it filling
up the landfills?
>
> Coincidentally, I have a rather large, 25-year-old sandpile that I
> would like to remove and cleanup. So, I could kill two birds with one
> stone.
Well, there is that. :-)
>
> I could, perhaps, build a small roof that would lay on top of the bags.
> Maybe I could make it out of heavy particle board and roll roofing.
> That would look better than simply throwing a sheet of plastic over the
> "bunker" to protect the bags from the sun. That might also provide some
> additional sound proofing. If I did that, I would still have the
> problem of sound proofing the open entrance that I would need to wheel
> the generator in and out of, though.
THat's easy - point it away from the house. :-)
> Nothing comes to mind at the moment for the entrance. So, I'll have to
> do some thinking about that. I suppose I could make an L-shaped
> entrance so that the sound would have to go around a corner to get out
> . . ."
Just line the room with some cheap shag carpet remnants - maybe drive
around and look for someone who's having their carpet replaced. Put up
a chimney for the exhaust; that'll get the noise farther away, plus
keep the exhaust fumes out of the intake, and out of the generator
room! :-)
Have Fun!
Rich
| |
| Anthony Matonak 2006-05-13, 5:21 pm |
| Rich Grise wrote:
....
> Aren't they made of plastic these days? If a poly or nylon or kevlar
> bag rots in only a few years, why are they all worried about it filling
> up the landfills?
Rot isn't exactly the right word. Ultraviolet light will cause most
plastics to decompose over time. It's exposure to sunlight that is
the problem.
Anthony
| |
| netster403@gmail.com 2006-05-14, 1:21 am |
| wow, i spawned alot of talk with my lineman electrocution post. :P
And about the transformer explosions... I really diddnt mean "explode"
but if you try to run an old pole transformer backward after it's been
running one direction for 10+ years, it may not like it and may fry
some windings on it. But hey who cares, that's the power company's
problem 
| |
| Vaughn Simon 2006-05-14, 11:21 am |
|
<netster403@gmail.com> wrote in message
news:1147578758.579872.134130@u72g2000cwu.googlegroups.com...
> but if you try to run an old pole transformer backward after it's been
> running one direction for 10+ years, it may not like it and may fry
> some windings on it.
Not true. A transformer does not care which direction it is passing power
and (in 100% AC operation) has no memory of such things.
Vaughn
| |
| Wes Stewart 2006-05-14, 11:21 am |
| On 13 May 2006 20:52:38 -0700, netster403@gmail.com wrote:
>wow, i spawned alot of talk with my lineman electrocution post. :P
>
>And about the transformer explosions... I really diddnt mean "explode"
>but if you try to run an old pole transformer backward after it's been
>running one direction for 10+ years, it may not like it and may fry
>some windings on it.
You're kidding, right?
I remember magnetic core memory, but I don't recall that power
transformers had this property.
| |
|
|
<netster403@gmail.com> wrote in message
news:1147578758.579872.134130@u72g2000cwu.googlegroups.com...
> wow, i spawned alot of talk with my lineman electrocution post. :P
>
> And about the transformer explosions... I really diddnt mean "explode"
> but if you try to run an old pole transformer backward after it's been
> running one direction for 10+ years, it may not like it and may fry
> some windings on it. But hey who cares, that's the power company's
> problem
>
Who cares? You'll care when they sue you for damages!
| |
|
|
"Vaughn Simon" <vaughnsimonHATESSPAM@att.FAKE.net> wrote in message
news:3dG9g.98286$eR6.11645@bgtnsc04-news.ops.worldnet.att.net...
>
> <netster403@gmail.com> wrote in message
> news:1147578758.579872.134130@u72g2000cwu.googlegroups.com...
>
> Not true. A transformer does not care which direction it is passing
> power and (in 100% AC operation) has no memory of such things.
>
> Vaughn
You can easily blow up a transformer when your generator current exceeds the
capacity of the transformer's secondary windings.
| |
| Vaughn Simon 2006-05-14, 4:21 pm |
|
"JoeSP" <olegp@telus.net> wrote in message news:QcK9g.19739$fV1.2856@edtnps82...
>
>
> You can easily blow up a transformer when your generator current exceeds the
> capacity of the transformer's secondary windings.
Joe, excuse me but that is a pretty strange statement. The transformer
that feeds my house is very typical and it is big enough to supply 100+ amps
@220 volts to four houses. Do you know anyone with a household genny big enough
to damage something like that? My biggest unit could put a whole 30 amps on one
110 Volt leg (OK, perhaps 60 for a second or so before the breaker tripped).
Vaughn
>
>
| |
| Michael A. Terrell 2006-05-14, 4:21 pm |
| JoeSP wrote:
>
> "Vaughn Simon" <vaughnsimonHATESSPAM@att.FAKE.net> wrote in message
> news:3dG9g.98286$eR6.11645@bgtnsc04-news.ops.worldnet.att.net...
>
> You can easily blow up a transformer when your generator current exceeds the
> capacity of the transformer's secondary windings.
I'd love to have a generator that big, but why would I need it?
Let's see: There are five homes on the same transformer, each with 200
amp 240 volt service so I would need 1000 amps, or a 240 KW generator to
match the normal supply available from that transformer. On the other
hand I rarely use over 60 amps at once, and its usually in the <20 amp
range so why would I even want a fuel hog like that? 5 KW is more than
enough to get by on for prolonged outages, I just can't use a welder or
a few of my bigger tools. I can run the well pump, refrigerator and
window AC off a 5 KW generator, although I would probably buy a 7.5 or
10 KW next time.
--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.
Michael A. Terrell
Central Florida
| |
|
| In article <1147578758.579872.134130@u72g2000cwu.googlegroups.com>,
netster403@gmail.com wrote:
> but if you try to run an old pole transformer backward after it's been
> running one direction for 10+ years, it may not like it and may fry
> some windings on it.
Absolute nonsense, where did you learn your basic electrics? Grade
School?
| |
| Jim Thompson 2006-05-14, 5:21 pm |
| On Sun, 14 May 2006 19:29:47 GMT, You <You@shadow.orgs> wrote:
>In article <1147578758.579872.134130@u72g2000cwu.googlegroups.com>,
> netster403@gmail.com wrote:
>
>
>Absolute nonsense, where did you learn your basic electrics? Grade
>School?
Nursery school ;-)
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
| |
|
|
"Vaughn Simon" <vaughnsimonHATESSPAM@att.FAKE.net> wrote in message
news:STK9g.99592$eR6.46373@bgtnsc04-news.ops.worldnet.att.net...
>
> "JoeSP" <olegp@telus.net> wrote in message
> news:QcK9g.19739$fV1.2856@edtnps82...
>
> Joe, excuse me but that is a pretty strange statement. The
> transformer that feeds my house is very typical and it is big enough to
> supply 100+ amps @220 volts to four houses. Do you know anyone with a
> household genny big enough to damage something like that? My biggest unit
> could put a whole 30 amps on one 110 Volt leg (OK, perhaps 60 for a second
> or so before the breaker tripped).
>
> Vaughn
It might seem strange to you but it happened when a farmer bought a surplus
generator, hooked it up to his 200 HP tractor, and fired it up. I don't
know if it was a 30 amp service or a 100 amp service, but it certainly made
an impressive fireworks display when the transformer exploded, showering
everything around with burning oil.
| |
|
| In article <1263uj968rr7n76@corp.supernews.com>,
>Don't US linemen either work using live circuit protocols, or tie the
>circuits to ground before working on them? The risk of some idiot
>energising what should be a dead circuit seems so obvious that I find it
>very hard to believe that they don't..
What if the "some idiot" was one of these green types that has their own
wind farm/solar panel setup that back-feeds spare power back into the
grid?
It's always puzzled me what happens when you've got one person in a street
with that kind of setup, and there's a cable break ... one person tries
to power the whole street ... linesman gets zapped from the "dead" side
of circuit etc ... mmm ... messy!
--
--------------------------------------+------------------------------------
Mike Brown: mjb[at]pootle.demon.co.uk | http://www.pootle.demon.co.uk/
| |
| Vaughn Simon 2006-05-14, 8:21 pm |
|
"JoeSP" <olegp@telus.net> wrote in message news:uvM9g.19769$fV1.6318@edtnps82...
>
>
> It might seem strange to you but it happened when a farmer bought a surplus
> generator, hooked it up to his 200 HP tractor, and fired it up. I don't know
> if it was a 30 amp service or a 100 amp service, but it certainly made an
> impressive fireworks display when the transformer exploded, showering
> everything around with burning oil.
Well, it is your story and I guess you are stuck with it, but is sounds
like a non sequitur to the topic to me. This thread started out with a question
about an 8KW backup generator. I doubt if there are many pole pigs that would
have trouble with 8KW, but even then it should blow a properly-sized primary
fuse rather than blow the transformer. I won't say it never happened, but it
would be a shame if someone got a false impression of danger from your post.
Regards
Vaughn
>
>
| |
| Michael A. Terrell 2006-05-14, 10:21 pm |
| Mike wrote:
>
> What if the "some idiot" was one of these green types that has their own
> wind farm/solar panel setup that back-feeds spare power back into the
> grid?
>
> It's always puzzled me what happens when you've got one person in a street
> with that kind of setup, and there's a cable break ... one person tries
> to power the whole street ... linesman gets zapped from the "dead" side
> of circuit etc ... mmm ... messy!
Not if it's designed properly. The small amount ow power available
won't "power the whole street" and it will disconnect from the line. Do
you think a utility would allow them to be set up to sell power without
the proper safeguards?
--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.
Michael A. Terrell
Central Florida
| |
| Rich Grise 2006-05-15, 3:21 pm |
| On Sat, 13 May 2006 20:52:38 -0700, netster403 wrote:
> wow, i spawned alot of talk with my lineman electrocution post. :P
>
> And about the transformer explosions... I really diddnt mean "explode"
> but if you try to run an old pole transformer backward after it's been
> running one direction for 10+ years, it may not like it and may fry
> some windings on it. But hey who cares, that's the power company's
> problem
Those explosions aren't the transformers exploding. It's the fuses. They
actually have explosive charges in their mongo fuses to literally blow out
the arc when there's a fault and the fuse is trying to open. This is at
hundreds, maybe thousands, of amps, and thousands, maybe tens of
thousands, of volts.
Cheers!
Rich
| |
|
| In article <QcK9g.19739$fV1.2856@edtnps82>, "JoeSP" <olegp@telus.net>
wrote:
> "Vaughn Simon" <vaughnsimonHATESSPAM@att.FAKE.net> wrote in message
> news:3dG9g.98286$eR6.11645@bgtnsc04-news.ops.worldnet.att.net...
>
> You can easily blow up a transformer when your generator current exceeds the
> capacity of the transformer's secondary windings.
>
>
You haven't been in the Electrical Utility Biz, or you would know that
most Pole Pigs are in the 20 to 100 Kw range. Very few of the Home Style
Gensets are capable of producing power at that Power Level......
| |
| Tom Horne, Electrician 2006-05-16, 7:21 pm |
| Mike wrote:
> In article <1263uj968rr7n76@corp.supernews.com>,
>
> What if the "some idiot" was one of these green types that has their own
> wind farm/solar panel setup that back-feeds spare power back into the
> grid?
>
> It's always puzzled me what happens when you've got one person in a street
> with that kind of setup, and there's a cable break ... one person tries
> to power the whole street ... linesman gets zapped from the "dead" side
> of circuit etc ... mmm ... messy!
>
All of the controllers designed to do this synchronize the output to the
frequency of the grid. If synchronization is lost the controllers
output ceases in less than one cycle.
--
Tom Horne
"This alternating current stuff is just a fad. It is much too dangerous
for general use." Thomas Alva Edison
| |
| JoeSP 2006-05-16, 11:21 pm |
|
"Tom Horne, Electrician" <hornetd@mindspring.com> wrote in message
news:9Drag.3051$x4.943@newsread3.news.pas.earthlink.net...
> Mike wrote:
[color=darkred]
>
> "This alternating current stuff is just a fad. It is much too dangerous
> for general use." Thomas Alva Edison
Pasted from Wikipedia: http://en.wikipedia.org/wiki/Electric_chair
In order to prove that AC electricity was dangerous and therefore better for
executions, Brown and Edison, who promoted DC electricity, publicly killed
many animals with AC, including a circus elephant. They held executions of
animals for the press in order to ensure that AC current was associated with
electrocution. It was at these events that the term "electrocution" was
coined. Edison introduced the verb "to westinghouse" for denoting the art of
executing persons with AC current. Most of their experiments were conducted
at Edison's West Orange, New Jersey, laboratory in 1888.
and from: http://en.wikipedia.org/wiki/Thomas_Edison
George Westinghouse and Edison became adversaries due to Edison's promotion
of direct current (DC) for electric power distribution over the more easily
transmitted alternating current (AC) system developed by Nikola Tesla and
sold by Westinghouse. Unlike DC, AC could be stepped up to very high
voltages with inexpensive transformers, sent over thinner wires, and stepped
down again at the destination for distribution to users.
Despite Edison's contempt for capital punishment, the war against AC led
Edison to become involved in the development and promotion of the electric
chair as a demonstration of AC's greater lethal potential versus the "safer"
DC. Edison went on to carry out a brief but intense campaign to ban the use
of AC or limit the allowable voltage for safety purposes. As part of this
campaign, Edison publicly electrocuted dogs, cats, and in one case, an
elephant[3] to demonstrate the dangers of AC. Widespread use of DC
ultimately lost favor, however, continuing primarily in long-distance
high-voltage direct current (HVDC) transmission systems.
| |
| Michael A. Terrell 2006-05-21, 3:21 am |
| Rich Grise wrote:
>
> On Sat, 13 May 2006 20:52:38 -0700, netster403 wrote:
>
>
> Those explosions aren't the transformers exploding. It's the fuses. They
> actually have explosive charges in their mongo fuses to literally blow out
> the arc when there's a fault and the fuse is trying to open. This is at
> hundreds, maybe thousands, of amps, and thousands, maybe tens of
> thousands, of volts.
>
> Cheers!
> Rich
So, you're trying to tell us that your pole pig is in the 10 MVA
range? Just how big IS that pole?
--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.
Michael A. Terrell
Central Florida
| |
|
| In article <4467C9E6.9F49AF17@earthlink.net>,
Michael A. Terrell <mike.terrell@earthlink.net> wrote:
>The small amount ow power available
>won't "power the whole street"
I did say "tries to ..."
> Do
>you think a utility would allow them to be set up to sell power without
>the proper safeguards?
I would hope not. However, we're back to the person with the generator with
13A plug (live) fitted on the end ... you would hope the utility wouldn't
allow that either, but people do retrofit stupid things onto existing good
systems, and they can go undetected for quite a while!
--
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Mike Brown: mjb[at]pootle.demon.co.uk | http://www.pootle.demon.co.uk/
| |
|
| In article <9Drag.3051$x4.943@newsread3.news.pas.earthlink.net>,
Tom Horne, Electrician <hornetd@mindspring.com> wrote:
>All of the controllers designed to do this synchronize the output to the
>frequency of the grid. If synchronization is lost the controllers
>output ceases in less than one cycle.
That's a good plan, that'll set my mind at rest for now
Mike.
--
--------------------------------------+------------------------------------
Mike Brown: mjb[at]pootle.demon.co.uk | http://www.pootle.demon.co.uk/
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