I'm just a nosy *******. But...
There are two substations, about a mile apart. One is on a pair of
wooden poles; the other is in a big box on the ground. They are both fed
from the same 11,000V network. The 235V outputs from these two
substations run towards each other along the street, until they meet on
the same pole. On that pole there are three fuse holders. It appears
that the fuses link the outputs from the two substations. For a while
men kept coming and trying to remove these fuses, but they wouldn't
unscrew. Finally they replaced the fuseholders, but left the fuses out,
dangling on a bit of wire. They are 200A fuses.

Am I right in thinking that the fuses link each of the three phases from
the two substations?

If so, why?

Why are the fuses not in place now?

Bill

williamwright wrote:
I'm just a nosy *******. But...
There are two substations, about a mile apart. One is on a pair of
wooden poles; the other is in a big box on the ground. They are both fed
from the same 11,000V network. The 235V outputs from these two
substations run towards each other along the street, until they meet on
the same pole. On that pole there are three fuse holders. It appears
that the fuses link the outputs from the two substations. For a while
men kept coming and trying to remove these fuses, but they wouldn't
unscrew. Finally they replaced the fuseholders, but left the fuses out,
dangling on a bit of wire. They are 200A fuses.

Am I right in thinking that the fuses link each of the three phases from
the two substations?

If so, why?

Why are the fuses not in place now?


Dunno but like you I have a bit of a fascination for for all our unseen
utilities and never miss an opportunity to peer down a hole in the road
etc.

Perhaps they need to break a €œring€� so as to do repair work and want to
minimise loss of power to properties. Jammed fuse holder maybe needed to
be replaced first before they could isolate a section?

Tim

--
Please don't feed the trolls

Maybe they have decided that the two are more likely to fail if connected
together so they have left them disconnected. Its one of those questions
which only power networks or whatever they are called this week can answer
with authority.
We are on the edge of an industrial estate and sub stations seem to pop up
in little fenced enclosures with amazing regularity, all buzzing away. When
one goes down it does seem not to follow any known logic as to which
premises lose power.
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"williamwright" wrote in message
...
I'm just a nosy *******. But...
There are two substations, about a mile apart. One is on a pair of wooden
poles; the other is in a big box on the ground. They are both fed from the
same 11,000V network. The 235V outputs from these two substations run
towards each other along the street, until they meet on the same pole. On
that pole there are three fuse holders. It appears that the fuses link the
outputs from the two substations. For a while men kept coming and trying
to remove these fuses, but they wouldn't unscrew. Finally they replaced
the fuseholders, but left the fuses out, dangling on a bit of wire. They
are 200A fuses.

Am I right in thinking that the fuses link each of the three phases from
the two substations?

If so, why?

Why are the fuses not in place now?

Bill

There are some very interesting smells when a sub station fails. Kind of
burnt oil mixed with soot.
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Tim+" wrote in message
...
williamwright wrote:
I'm just a nosy *******. But...
There are two substations, about a mile apart. One is on a pair of
wooden poles; the other is in a big box on the ground. They are both fed
from the same 11,000V network. The 235V outputs from these two
substations run towards each other along the street, until they meet on
the same pole. On that pole there are three fuse holders. It appears
that the fuses link the outputs from the two substations. For a while
men kept coming and trying to remove these fuses, but they wouldn't
unscrew. Finally they replaced the fuseholders, but left the fuses out,
dangling on a bit of wire. They are 200A fuses.

Am I right in thinking that the fuses link each of the three phases from
the two substations?

If so, why?

Why are the fuses not in place now?


Dunno but like you I have a bit of a fascination for for all our unseen
utilities and never miss an opportunity to peer down a hole in the road
etc.

Perhaps they need to break a "ring" so as to do repair work and want to
minimise loss of power to properties. Jammed fuse holder maybe needed to
be replaced first before they could isolate a section?

Tim

--
Please don't feed the trolls

Brian Gaff (Sofa) wrote

There are some very interesting smells when a sub station fails. Kind of
burnt oil mixed with soot.

That’s just the remains of the fried electricity person.

"Tim+" wrote in message
...
williamwright wrote:
I'm just a nosy *******. But...
There are two substations, about a mile apart. One is on a pair of
wooden poles; the other is in a big box on the ground. They are both fed
from the same 11,000V network. The 235V outputs from these two
substations run towards each other along the street, until they meet on
the same pole. On that pole there are three fuse holders. It appears
that the fuses link the outputs from the two substations. For a while
men kept coming and trying to remove these fuses, but they wouldn't
unscrew. Finally they replaced the fuseholders, but left the fuses out,
dangling on a bit of wire. They are 200A fuses.

Am I right in thinking that the fuses link each of the three phases from
the two substations?

If so, why?

Why are the fuses not in place now?


Dunno but like you I have a bit of a fascination for for all our unseen
utilities and never miss an opportunity to peer down a hole in the road
etc.

Perhaps they need to break a "ring" so as to do repair work and want to
minimise loss of power to properties. Jammed fuse holder maybe needed to
be replaced first before they could isolate a section?

Tim

--
Please don't feed the trolls

On 07/08/2020 04:42, williamwright wrote:
I'm just a nosy *******. But...
There are two substations, about a mile apart. One is on a pair of
wooden poles; the other is in a big box on the ground. They are both fed
from the same 11,000V network. The 235V outputs from these two
substations run towards each other along the street, until they meet on
the same pole. On that pole there are three fuse holders. It appears
that the fuses link the outputs from the two substations. For a while
men kept coming and trying to remove these fuses, but they wouldn't
unscrew. Finally they replaced the fuseholders, but left the fuses out,
dangling on a bit of wire. They are 200A fuses.

Am I right in thinking that the fuses link each of the three phases from
the two substations?

Probably

If so, why?

To be able to quickly backfeed either low voltage distribution circuit
in the event of the failure of a substation or part of one of the
circuits if the circuit breaks.

Why are the fuses not in place now?

No current need to backfeed either low voltage circuit, after a period
when there was.
--
Andrew

On Fri, 7 Aug 2020 17:23:54 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:

FLUSH the trolling senile asshole's latest troll**** unread

--
FredXX to Rodent Speed:
"You are still an idiot and an embarrassment to your country. No wonder
we shipped the likes of you out of the British Isles. Perhaps stupidity
and criminality is inherited after all?"
Message-ID:

On 07/08/2020 04:42, williamwright wrote:
I'm just a nosy *******. But...
There are two substations, about a mile apart. One is on a pair of
wooden poles; the other is in a big box on the ground. They are both fed
from the same 11,000V network. The 235V outputs from these two
substations run towards each other along the street, until they meet on
the same pole. On that pole there are three fuse holders. It appears
that the fuses link the outputs from the two substations. For a while
men kept coming and trying to remove these fuses, but they wouldn't
unscrew. Finally they replaced the fuseholders, but left the fuses out,
dangling on a bit of wire. They are 200A fuses.

Am I right in thinking that the fuses link each of the three phases from
the two substations?

If so, why?

Why are the fuses not in place now?

Bill


For reasons of diversity and reliability:

LV distribution in the street is done as a virtual "ring main" with two
independent & seperate feeds from the 11 kV HV network via transformers.

The ring main is NEVER fully compelete/closed via all its switches,
there are switches all round this virtual ring main. They can sometimes
look like fuses but are in fact metal fusible link bars rather than
cartridge fuses.

All of the switches are closed are closed but two sets are delibereately
left open in the ring main.

All round this ring main are the service cables connecting the
households to this ring main.

This splits the ring intwo two distinct parts. One part of this "ring"
is fed from one of the HV feeds and the other part is fed from another
HV feed.

So things like power cuts can be "managed" or network maintenance work
to take place with minimal disruption. Consider the following scenarios:

Say one of the HV feeds fails, the now unpowered transformer is switched
off and isolated from the ring main.

Then one or both of the open switches in the ring main is closed so that
the part ring is then re-energised using the other HV feed as it has now
been combined with the still working part ring.

Say part of the ring main needs isolating for routine maintenance work.

Rather than cut off one HV feed and de-energine the WHOLE of the part
ring main, they simply open the switch downstream AND upstream of the
works location. The other open switches are then closed to re-energise
the remaining parts of that ring and then the works can be undertaken.

If there is a short circuit fault tripping a fuse, rather than fix the
fault and let everyone suffer a power cut, the fault can be isolated
between two adjacent pairs of switches and the power restored to those
upstream and downstream of the two switches before and after the fault.
This allows power to be restored to some of teh customers sonner than
expected. Then only those fed by the isoloated section of faulty ring
main have to have the full power cut experience. :-)


Similarly if a ring main cable goes open circuit, this then creates a
new 3rd split ring main. One of the open switches can be closed to power
up the 3rd split ring until teh open circuit fault can be repaired.

Similar arrangements exist for the Supergrid ( 400 kV & 275 kV) to the
national grid (132kV, 66kV ) and then down to the Local distribution
grid ( 33kV and 11kV).

There is also a PE system (Potential Earth) which is a safety system
for engineers working on parts of the grid but it does involve quite
some complicated switching and involves a permit system.

Lets say the mineral oil in the 11kV to 220V transformer or HV switch
needs changing... There is a person that literally drives around in a
car with a bunch of keys to all the substations and a check list of the
EXACT order and WHICH EXACT switches to open or close or apply potential
earth.

All of the switches also have an option to apply potential earth which
is a connection to an earth rod on site.

basically I went out for a ride in the car. Basically they:

Drive to Switch A. Close it. This then combines the two parts of the
split ring at one end.

Drive to switch B. Close it. This then completes the ring main which is
now fed via two HV feeds simultaneously. This will be temporary though....

Drive to switch C. Open it. This will be downstream of the ring main
cable coming from the transformer's secondary output

Drive to Switch D. Open it . This will be upstream of the ring main
cable coming from the transformer's secondary output

Drive to Switch E. Open it, This then disconnects the transformer's
primary from the HV feed.

Then the Transformer's primary is switched to earth.

drive back to switch C. The downstream cable from transformer's
secondary is switched to Potential earth.

Drive back to switch D. The upstream cable from transformer's secondary
is switched to Potential earth.

Then we drive to the EXACT location of where the transfomer whose oil is
to be changed. The safety paperwork is then given to the team doing the
work. They then have authorisation to apply all conenctions to and from
this transformer to potewntial earth.

All being well there will be no bangs/explosions or sudden power cuts
and no one is in trouble for noe following the switch order and location
list EXACTLY!

Then when the oil change is completed, the list above is then repeated
but in reverse to effectively bring the transformer back into use.

Obviously Potential earth should NOT be connected to a live cable or
power applied to a potential earth rod!

How do I know all this? from 1 weeks' work experience spent with the MEB
(Midlands Electricity Board) and with the National Grid in 1986 as a
spotty 15 year old inquisitive & enquiring lad!....

Nowaways I expect all the switching is now done remotely over the net
for much of the network but obviously this will not apply for parts that
have not been updated to internet remote management.

williamwright wrote :
Am I right in thinking that the fuses link each of the three phases from the
two substations?

My Guess....

Yes, the three phases and the option to be able to link them so street
can be entirely fed from either end, in case one supply fails.

williamwright wrote:
I'm just a nosy *******. But...
There are two substations, about a mile apart. One is on a pair of
wooden poles; the other is in a big box on the ground. They are both fed
from the same 11,000V network. The 235V outputs from these two
substations run towards each other along the street, until they meet on
the same pole. On that pole there are three fuse holders. It appears
that the fuses link the outputs from the two substations. For a while
men kept coming and trying to remove these fuses, but they wouldn't
unscrew. Finally they replaced the fuseholders, but left the fuses out,
dangling on a bit of wire. They are 200A fuses.

Am I right in thinking that the fuses link each of the three phases from
the two substations?

If so, why?

Why are the fuses not in place now?

Bill

It's a backup power plan of some sort.

But 235W at 200A times three phase ?
That's not exactly Hoover Dam.

That's a small amount of power as a backup.
There might be a single industrial customer
at the end of that.

The fuses stay open, because the line is
not to be energized in normal mode.

I have three fuses hanging down like that,
a five minute walk from the house. And I've
never seen that backup used, ever. Even when
our substation was down for construction work,
that still wasn't engaged. The wires from it,
just run off into the "forest". So you can't
see the terminus.

Paul

On 07/08/2020 08:33, Andrew Gabriel wrote:
On 07/08/2020 04:42, williamwright wrote:
I'm just a nosy *******. But...
There are two substations, about a mile apart. One is on a pair of
wooden poles; the other is in a big box on the ground. They are both
fed from the same 11,000V network. The 235V outputs from these two
substations run towards each other along the street, until they meet
on the same pole. On that pole there are three fuse holders. It
appears that the fuses link the outputs from the two substations. For
a while men kept coming and trying to remove these fuses, but they
wouldn't unscrew. Finally they replaced the fuseholders, but left the
fuses out, dangling on a bit of wire. They are 200A fuses.

Am I right in thinking that the fuses link each of the three phases
from the two substations?

Probably

If so, why?

To be able to quickly backfeed either low voltage distribution circuit
in the event of the failure of a substation or part of one of the
circuits if the circuit breaks.

Why are the fuses not in place now?

No current need to backfeed either low voltage circuit, after a period
when there was.

+1

No Name wrote:
On 07/08/2020 04:42, williamwright wrote:
I'm just a nosy *******. But...
There are two substations, about a mile apart. One is on a pair of
wooden poles; the other is in a big box on the ground. They are both
fed from the same 11,000V network. The 235V outputs from these two
substations run towards each other along the street, until they meet
on the same pole. On that pole there are three fuse holders. It
appears that the fuses link the outputs from the two substations. For
a while men kept coming and trying to remove these fuses, but they
wouldn't unscrew. Finally they replaced the fuseholders, but left the
fuses out, dangling on a bit of wire. They are 200A fuses.

Am I right in thinking that the fuses link each of the three phases
from the two substations?

If so, why?

Why are the fuses not in place now?

Bill


For reasons of diversity and reliability:

LV distribution in the street is done as a virtual "ring main" with two
independent & seperate feeds from the 11 kV HV network via transformers.

The ring main is NEVER fully compelete/closed via all its switches,
there are switches all round this virtual ring main. They can sometimes
look like fuses but are in fact metal fusible link bars rather than
cartridge fuses.

All of the switches are closed are closed but two sets are delibereately
left open in the ring main.

All round this ring main are the service cables connecting the
households to this ring main.

This splits the ring intwo two distinct parts. One part of this "ring"
is fed from one of the HV feeds and the other part is fed from another
HV feed.

So things like power cuts can be "managed" or network maintenance work
to take place with minimal disruption. Consider the following scenarios:

Say one of the HV feeds fails, the now unpowered transformer is switched
off and isolated from the ring main.

Then one or both of the open switches in the ring main is closed so that
the part ring is then re-energised using the other HV feed as it has now
been combined with the still working part ring.

Say part of the ring main needs isolating for routine maintenance work.

Rather than cut off one HV feed and de-energine the WHOLE of the part
ring main, they simply open the switch downstream AND upstream of the
works location. The other open switches are then closed to re-energise
the remaining parts of that ring and then the works can be undertaken.

If there is a short circuit fault tripping a fuse, rather than fix the
fault and let everyone suffer a power cut, the fault can be isolated
between two adjacent pairs of switches and the power restored to those
upstream and downstream of the two switches before and after the fault.
This allows power to be restored to some of teh customers sonner than
expected. Then only those fed by the isoloated section of faulty ring
main have to have the full power cut experience. :-)


Similarly if a ring main cable goes open circuit, this then creates a
new 3rd split ring main. One of the open switches can be closed to power
up the 3rd split ring until teh open circuit fault can be repaired.

Similar arrangements exist for the Supergrid ( 400 kV & 275 kV) to the
national grid (132kV, 66kV ) and then down to the Local distribution
grid ( 33kV and 11kV).

There is also a PE system (Potential Earth) which is a safety system
for engineers working on parts of the grid but it does involve quite
some complicated switching and involves a permit system.

Lets say the mineral oil in the 11kV to 220V transformer or HV switch
needs changing... There is a person that literally drives around in a
car with a bunch of keys to all the substations and a check list of the
EXACT order and WHICH EXACT switches to open or close or apply potential
earth.

All of the switches also have an option to apply potential earth which
is a connection to an earth rod on site.

basically I went out for a ride in the car. Basically they:

Drive to Switch A. Close it. This then combines the two parts of the
split ring at one end.

Drive to switch B. Close it. This then completes the ring main which is
now fed via two HV feeds simultaneously. This will be temporary though....

Drive to switch C. Open it. This will be downstream of the ring main
cable coming from the transformer's secondary output

Drive to Switch D. Open it . This will be upstream of the ring main
cable coming from the transformer's secondary output

Drive to Switch E. Open it, This then disconnects the transformer's
primary from the HV feed.

Then the Transformer's primary is switched to earth.

drive back to switch C. The downstream cable from transformer's
secondary is switched to Potential earth.

Drive back to switch D. The upstream cable from transformer's secondary
is switched to Potential earth.

Then we drive to the EXACT location of where the transfomer whose oil is
to be changed. The safety paperwork is then given to the team doing the
work. They then have authorisation to apply all conenctions to and from
this transformer to potewntial earth.

All being well there will be no bangs/explosions or sudden power cuts
and no one is in trouble for noe following the switch order and location
list EXACTLY!

Then when the oil change is completed, the list above is then repeated
but in reverse to effectively bring the transformer back into use.

Obviously Potential earth should NOT be connected to a live cable or
power applied to a potential earth rod!

How do I know all this? from 1 weeks' work experience spent with the MEB
(Midlands Electricity Board) and with the National Grid in 1986 as a
spotty 15 year old inquisitive & enquiring lad!....

Nowaways I expect all the switching is now done remotely over the net
for much of the network but obviously this will not apply for parts that
have not been updated to internet remote management.

How is this monitored ?

It sounds manpower intensive.

Even when energizing a circuit here is relatively
straight forward, the safety checks take forever.
Twenty years ago, they were a lot faster at
putting things back in working order (they did safety
checks, but nobody was standing around and everyone
was working to bring it back up). Today, there are
a *lot* of guys just standing around. And somehow
it's safer.

Now that we have digital power meters, they have visibility
at the fused circuit level. So they can tell a fuse is open,
just by noting which chunk of houses doesn't have power. Whereas
before, part of the truck roll, was driving along the
street at night with a search light, and examining the fuses
as they went. The substations all have remote monitoring and
control. But out at street level, the digital meters added
a lot of visibility for the smaller stubs of distribution.
They can tell that the fuse at the end of the street which
powers five houses, is open. Because five dots disappeared
from the "map". If multiple fuses failed, only the outermost
one would be identified by the computer.

That doesn't make the repair any easier though. They don't
close a fuse here, unless some kind of check says it's
ready to go. I've never seen what they use to determine
that. But I was told by a lineman one day, that he couldn't
do anything just yet, until the line was verified first.
And he wasn't doing the checking. He'd loaded a new fuse,
had the pole ready to close it, but was... waiting.

Paul

On 07/08/2020 10:53, Paul wrote:
But 235W at 200A times three phase ?
That's not exactly Hoover Dam.

235 VOLTS Paul. That's the typical UK
low voltage distribution distribution to domestic
premises (who have 1 phase and neutral) and small businesses
(who probably have all three phases and neutral,nominally 430
Volts). Both might get some sort of energy supplier-provided earth,
or not.

The HV stuff, 3.3KV, 6.6Kv, 11KV, 33KV .... never go to any
domestic premises. Bigger commercial users might have their own
HV/LV transformer on site behind a security fence if ground-mounted

On 07/08/2020 04:42, williamwright wrote:
I'm just a nosy *******. But...
There are two substations, about a mile apart. One is on a pair of
wooden poles; the other is in a big box on the ground. They are both fed
from the same 11,000V network. The 235V outputs from these two
substations run towards each other along the street, until they meet on
the same pole. On that pole there are three fuse holders. It appears
that the fuses link the outputs from the two substations. For a while
men kept coming and trying to remove these fuses, but they wouldn't
unscrew. Finally they replaced the fuseholders, but left the fuses out,
dangling on a bit of wire. They are 200A fuses.

Am I right in thinking that the fuses link each of the three phases from
the two substations?

If so, why?

Why are the fuses not in place now?

Bill

Some very informative answers! Thank you!

Bill

Andrew wrote:
On 07/08/2020 10:53, Paul wrote:
But 235W at 200A times three phase ?
That's not exactly Hoover Dam.

235 VOLTS Paul. That's the typical UK
low voltage distribution distribution to domestic
premises (who have 1 phase and neutral) and small businesses
(who probably have all three phases and neutral,nominally 430
Volts). Both might get some sort of energy supplier-provided earth,
or not.

The HV stuff, 3.3KV, 6.6Kv, 11KV, 33KV .... never go to any
domestic premises. Bigger commercial users might have their own
HV/LV transformer on site behind a security fence if ground-mounted

But messing around with "amps" at that level,
doesn't make a lot of sense. To distribute the last
level of power over large distances requires outsized
cables. There's only so much voltage drop in the
budget for your 235 volts.

That was my point.

How large a diameter of ring makes sense at 200 amps ?

Using "schemes" at higher levels in the distribution
makes a bit more sense, because there's a possibility
of using fewer amps. We could probably benefit from
a ring scheme at the next level up (that might fix the
voltage drop issue seen here).

The lowest level of distribution here, goes directly
to a consumer with one fuse in the way at that level.

The next level up is still fused.

The levels above that are automatic switch gear and
remote control and monitoring.

Paul

In article ,
Paul wrote:
Andrew wrote:
On 07/08/2020 10:53, Paul wrote:
But 235W at 200A times three phase ?
That's not exactly Hoover Dam.

235 VOLTS Paul. That's the typical UK
low voltage distribution distribution to domestic
premises (who have 1 phase and neutral) and small businesses
(who probably have all three phases and neutral,nominally 430
Volts). Both might get some sort of energy supplier-provided earth,
or not.

The HV stuff, 3.3KV, 6.6Kv, 11KV, 33KV .... never go to any
domestic premises. Bigger commercial users might have their own
HV/LV transformer on site behind a security fence if ground-mounted

But messing around with "amps" at that level,
doesn't make a lot of sense. To distribute the last
level of power over large distances requires outsized
cables. There's only so much voltage drop in the
budget for your 235 volts.

That was my point.

How large a diameter of ring makes sense at 200 amps ?

Using "schemes" at higher levels in the distribution
makes a bit more sense, because there's a possibility
of using fewer amps. We could probably benefit from
a ring scheme at the next level up (that might fix the
voltage drop issue seen here).

There's certainly a 33kV ring in West London. I assume there are plentyof
others, but that's the only one I've come across.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

On Saturday, 8 August 2020 14:07:05 UTC+1, Paul wrote:
Andrew wrote:
On 07/08/2020 10:53, Paul wrote:
But 235W at 200A times three phase ?
That's not exactly Hoover Dam.

235 VOLTS Paul. That's the typical UK
low voltage distribution distribution to domestic
premises (who have 1 phase and neutral) and small businesses
(who probably have all three phases and neutral,nominally 430
Volts). Both might get some sort of energy supplier-provided earth,
or not.

The HV stuff, 3.3KV, 6.6Kv, 11KV, 33KV .... never go to any
domestic premises. Bigger commercial users might have their own
HV/LV transformer on site behind a security fence if ground-mounted

But messing around with "amps" at that level,
doesn't make a lot of sense. To distribute the last
level of power over large distances requires outsized
cables. There's only so much voltage drop in the
budget for your 235 volts.

That was my point.

How large a diameter of ring makes sense at 200 amps ?

Using "schemes" at higher levels in the distribution
makes a bit more sense, because there's a possibility
of using fewer amps. We could probably benefit from
a ring scheme at the next level up (that might fix the
voltage drop issue seen here).

The lowest level of distribution here, goes directly
to a consumer with one fuse in the way at that level.

The next level up is still fused.

The levels above that are automatic switch gear and
remote control and monitoring.

Paul

I don't know how large 240v distribution circuits are, but certainly a whole street can run on one. Tap changers can compensate for V drop to an extent. I've no idea if they feed distribution runs from more than one point at once.

Turn of the century diagrams showed how to even out v drop on lighting circuits by feeding the L from one end & the N from the other. Result: all lamps see the same voltage. I've no idea whether similar games are played today in distribution.


NT

wrote:
On Saturday, 8 August 2020 14:07:05 UTC+1, Paul wrote:
Andrew wrote:
On 07/08/2020 10:53, Paul wrote:
But 235W at 200A times three phase ?
That's not exactly Hoover Dam.
235 VOLTS Paul. That's the typical UK
low voltage distribution distribution to domestic
premises (who have 1 phase and neutral) and small businesses
(who probably have all three phases and neutral,nominally 430
Volts). Both might get some sort of energy supplier-provided earth,
or not.

The HV stuff, 3.3KV, 6.6Kv, 11KV, 33KV .... never go to any
domestic premises. Bigger commercial users might have their own
HV/LV transformer on site behind a security fence if ground-mounted
But messing around with "amps" at that level,
doesn't make a lot of sense. To distribute the last
level of power over large distances requires outsized
cables. There's only so much voltage drop in the
budget for your 235 volts.

That was my point.

How large a diameter of ring makes sense at 200 amps ?

Using "schemes" at higher levels in the distribution
makes a bit more sense, because there's a possibility
of using fewer amps. We could probably benefit from
a ring scheme at the next level up (that might fix the
voltage drop issue seen here).

The lowest level of distribution here, goes directly
to a consumer with one fuse in the way at that level.

The next level up is still fused.

The levels above that are automatic switch gear and
remote control and monitoring.

Paul

I don't know how large 240v distribution circuits are, but certainly a whole street can run on one. Tap changers can compensate for V drop to an extent. I've no idea if they feed distribution runs from more than one point at once.

Turn of the century diagrams showed how to even out v drop on lighting circuits by feeding the L from one end & the N from the other. Result: all lamps see the same voltage. I've no idea whether similar games are played today in distribution.


NT

I just checked my line voltage, and at the moment, it
is not compliant with the spec. It's outside the acceptable
range, and there is no set of abnormal conditions here today.

That means at least my electric company does not know
how to equalize voltages along their "long-string"
wiring plan :-( I've put up with this for years, and
talking to those people is a waste of time.

To show how little they have in engineering skills,
they did attempt to change the wiring plan in my
neighborhood. At 10PM at night, they did the cutover.
The result was so bad, they had to cut back to the
old plan soon after. So much for ohms-law and
that hand calculator they own.

Not all of our cities are like that. The operator here,
is owned by the city, and the city receives a "dividend"
each year from the operation of the power company.

Paul

In article , williamwright
writes
I'm just a nosy *******. But...
There are two substations, about a mile apart. One is on a pair of
wooden poles; the other is in a big box on the ground. They are both
fed from the same 11,000V network. The 235V outputs from these two
substations run towards each other along the street, until they meet on
the same pole. On that pole there are three fuse holders. It appears
that the fuses link the outputs from the two substations. For a while
men kept coming and trying to remove these fuses, but they wouldn't
unscrew. Finally they replaced the fuseholders, but left the fuses out,
dangling on a bit of wire. They are 200A fuses.

Am I right in thinking that the fuses link each of the three phases
from the two substations?

If so, why?

Why are the fuses not in place now?

Bill
Probably got better protection in each sub station - and remotely
controllable.
--
bert