I believe someone was recently talking about voltage spikes, though I
can't find the thread in Google Groups to hang this on. I happened to
be watching my consumption thingy this morning and noticed that it was
constant at 249 volts. Then it went up to 250 for 30 seconds, back
down to 249, then back up to 250 again. For a good five minutes it
hovered around 249-250. Then it came down to 248, then 247.

Aren't these spikes damaging to sensitive equipment? (TVs, DVD Players
etc) I don't worry about the PC because I have a UPS on it. The
voltage is ~supposed~ to be 240 in the UK.

MM

On 08/03/2011 09:09, MM wrote:
I believe someone was recently talking about voltage spikes, though I
can't find the thread in Google Groups to hang this on. I happened to
be watching my consumption thingy this morning and noticed that it was
constant at 249 volts. Then it went up to 250 for 30 seconds, back
down to 249, then back up to 250 again. For a good five minutes it
hovered around 249-250. Then it came down to 248, then 247.

Aren't these spikes damaging to sensitive equipment? (TVs, DVD Players
etc) I don't worry about the PC because I have a UPS on it. The
voltage is ~supposed~ to be 240 in the UK.

MM

Voltage in the UK was harmonised with Europe on 1st January 1995 and is
supposed to be 230V +10%-6% (216.2–253 V).

So, your fluctuations are within tolerance. Most equipment is designed
to work at 110v - 220v (at 50 or 60Hz) look at the rating plate. That
voltage is nominal and will not include the tolerance.

Cheers

Peter

In message , puffernutter
writes
On 08/03/2011 09:09, MM wrote:
I believe someone was recently talking about voltage spikes, though I
can't find the thread in Google Groups to hang this on. I happened to
be watching my consumption thingy this morning and noticed that it was
constant at 249 volts. Then it went up to 250 for 30 seconds, back
down to 249, then back up to 250 again. For a good five minutes it
hovered around 249-250. Then it came down to 248, then 247.

Aren't these spikes damaging to sensitive equipment? (TVs, DVD Players
etc) I don't worry about the PC because I have a UPS on it. The
voltage is ~supposed~ to be 240 in the UK.

MM

Voltage in the UK was harmonised with Europe on 1st January 1995 and is
supposed to be 230V +10%-6% (216.2€“253 V).

So, your fluctuations are within tolerance. Most equipment is designed
to work at 110v - 220v (at 50 or 60Hz) look at the rating plate. That
voltage is nominal and will not include the tolerance.

Some time before Christmas, I inherited from a deceased works colleague
a purpose-built home-made meter for measuring the mains voltage (a 4"
moving-coil meter + rectifier). After testing it and tweaking it
slightly so that it read correctly at 230V, I left it plugged in,
sitting on the desk, so that I could instantly see how the mains was
doing. I have seen some considerable variations.

Before Christmas, the typical 'normal' voltage was 230V, occasionally
going up to 235. However, when the really cold weather started, after
around 5pm, the voltage would start to drop and, on several days,
regularly fell to 215V. The lowest (checked on a couple of digital
meters) was 214.4V.

After the New Year, have noticed that the typical 'normal' seems to be
235V (even when it was still very cold), and I occasionally see as high
as 245V. [Presumably someone decided to change the output tap at the
substation.] However, a couple of nights ago, I noticed that, every 30
seconds or so, the lights were very obviously suddenly going alternately
dim and bright. The mains was abruptly jumping between 230 and 220V, and
I was rather concerned that this might indicate that a power cut was
about to happen. However, an hour later, things settled down, and the
mains was a steady 235V again.
--
Ian

On Tue, 8 Mar 2011 10:27:33 +0000, Ian Jackson
wrote:

Before Christmas, the typical 'normal' voltage was 230V, occasionally
going up to 235. However, when the really cold weather started, after
around 5pm, the voltage would start to drop and, on several days,
regularly fell to 215V. The lowest (checked on a couple of digital
meters) was 214.4V.

I don't measure the mains voltage but I do notice fluctuations. All
the lights dim noticably in the house for a short time. It happens
fairly frequently in the early evening. It does not appear to cause
any problems to computers etc.

--
(\__/) M.
(='.'=) Due to the amount of spam posted via googlegroups and
(")_(") their inaction to the problem. I am blocking some articles
posted from there. If you wish your postings to be seen by
everyone you will need use a different method of posting.

In article ,
lid says...
I don't measure the mains voltage but I do notice fluctuations. All
the lights dim noticably in the house for a short time. It happens
fairly frequently in the early evening. It does not appear to cause
any problems to computers etc.


Nor should it - SMPS should be very tolerant of such things - after all,
they're usually considerably over rated in PC applications and only have
to up the duty-cycle briefly.

--
Skipweasel - never knowingly understood.

On Tue, 8 Mar 2011 17:18:17 -0000, Skipweasel
wrote:

In article ,
says...
I don't measure the mains voltage but I do notice fluctuations. All
the lights dim noticably in the house for a short time. It happens
fairly frequently in the early evening. It does not appear to cause
any problems to computers etc.

Nor should it - SMPS should be very tolerant of such things - after all,
they're usually considerably over rated in PC applications and only have
to up the duty-cycle briefly.

I was using this more as an indication of how long the light dimmed
for ;-) I am more interested if there is a problem with the supply.
--
(\__/) M.
(='.'=) Due to the amount of spam posted via googlegroups and
(")_(") their inaction to the problem. I am blocking some articles
posted from there. If you wish your postings to be seen by
everyone you will need use a different method of posting.

Skipweasel writes:

the lights dim noticably in the house for a short time. It happens
fairly frequently in the early evening. It does not appear to cause
any problems to computers etc.
Nor should it - SMPS should be very tolerant of such things - after all,
they're usually considerably over rated in PC applications and only have
to up the duty-cycle briefly.

Especially when nowadays many are designed to work over a range of
input voltages from 100V to 260V without even changing a switch
position.

--
Windmill, Use t m i l l
@ O n e t e l
. c o m

On Mar 8, 10:27*am, Ian Jackson
wrote:
In message , puffernutter
writes

On 08/03/2011 09:09, MM wrote:
I believe someone was recently talking about voltage spikes, though I
can't find the thread in Google Groups to hang this on. I happened to
be watching my consumption thingy this morning and noticed that it was
constant at 249 volts. Then it went up to 250 for 30 seconds, back
down to 249, then back up to 250 again. For a good five minutes it
hovered around 249-250. Then it came down to 248, then 247.

Aren't these spikes damaging to sensitive equipment? (TVs, DVD Players
etc) I don't worry about the PC because I have a UPS on it. The
voltage is ~supposed~ to be 240 in the UK.

MM

Voltage in the UK was harmonised with Europe on 1st January 1995 and is
supposed to be 230V +10%-6% (216.2–253 V).

So, your fluctuations are within tolerance. *Most equipment is designed
to work at 110v - 220v (at 50 or 60Hz) look at the rating plate. *That
voltage is nominal and will not include the tolerance.

Some time before Christmas, I inherited from a deceased works colleague
a purpose-built home-made meter for measuring the mains voltage (a 4"
moving-coil meter + rectifier). After testing it and tweaking it
slightly so that it read correctly at 230V, I left it plugged in,
sitting on the desk, so that I could instantly see how the mains was
doing. I have seen some considerable variations.

Before Christmas, the typical 'normal' voltage was 230V, occasionally
going up to 235. However, when the really cold weather started, after
around 5pm, the voltage would start to drop and, on several days,
regularly fell to 215V. The lowest (checked on a couple of digital
meters) was 214.4V.

After the New Year, have noticed that the typical 'normal' seems to be
235V (even when it was still very cold), and I occasionally see as high
as 245V. [Presumably someone decided to change the output tap at the
substation.] However, a couple of nights ago, I noticed that, every 30
seconds or so, the lights were very obviously suddenly going alternately
dim and bright. The mains was abruptly jumping between 230 and 220V, and
I was rather concerned that this might indicate that a power cut was
about to happen. However, an hour later, things settled down, and the
mains was a steady 235V again.
--
Ian

but did the frequency go down with the volts? I have a far eastern
LED Lloytron clock that seems to sync to the mains. If the frequency
goes down the clock runs slow.

rusty

In message
,
therustyone writes
On Mar 8, 10:27Â*am, Ian Jackson
wrote:
In message , puffernutter
writes

On 08/03/2011 09:09, MM wrote:
I believe someone was recently talking about voltage spikes, though I
can't find the thread in Google Groups to hang this on. I happened to
be watching my consumption thingy this morning and noticed that it was
constant at 249 volts. Then it went up to 250 for 30 seconds, back
down to 249, then back up to 250 again. For a good five minutes it
hovered around 249-250. Then it came down to 248, then 247.

Aren't these spikes damaging to sensitive equipment? (TVs, DVD Players
etc) I don't worry about the PC because I have a UPS on it. The
voltage is ~supposed~ to be 240 in the UK.

MM

Voltage in the UK was harmonised with Europe on 1st January 1995 and is
supposed to be 230V +10%-6% (216.2€“253 V).

So, your fluctuations are within tolerance. Â*Most equipment is designed
to work at 110v - 220v (at 50 or 60Hz) look at the rating plate. Â*That
voltage is nominal and will not include the tolerance.

Some time before Christmas, I inherited from a deceased works colleague
a purpose-built home-made meter for measuring the mains voltage (a 4"
moving-coil meter + rectifier). After testing it and tweaking it
slightly so that it read correctly at 230V, I left it plugged in,
sitting on the desk, so that I could instantly see how the mains was
doing. I have seen some considerable variations.

Before Christmas, the typical 'normal' voltage was 230V, occasionally
going up to 235. However, when the really cold weather started, after
around 5pm, the voltage would start to drop and, on several days,
regularly fell to 215V. The lowest (checked on a couple of digital
meters) was 214.4V.

After the New Year, have noticed that the typical 'normal' seems to be
235V (even when it was still very cold), and I occasionally see as high
as 245V. [Presumably someone decided to change the output tap at the
substation.] However, a couple of nights ago, I noticed that, every 30
seconds or so, the lights were very obviously suddenly going alternately
dim and bright. The mains was abruptly jumping between 230 and 220V, and
I was rather concerned that this might indicate that a power cut was
about to happen. However, an hour later, things settled down, and the
mains was a steady 235V again.
--
Ian

but did the frequency go down with the volts? I have a far eastern
LED Lloytron clock that seems to sync to the mains. If the frequency
goes down the clock runs slow.

No. I haven't been monitoring the mains frequency. I've only been
keeping an eye on the volts (simply because I acquired the meter, which
sits permanently plugged in, on a corner of the desk).

I was surprised to see how low the voltage sometimes went (right down to
the minimum limit). When it was really cold over Christmas and New Year,
I expect the guys at the power stations were shovelling coal for all
they were worth, and that the frequency (which is of less interest than
the voltage) was well down on normal.

Obviously, any type of clock which uses the mains frequency will run
fast or slow if the frequency varies. My understanding is that the
generating people are supposed make sure that, come hell or high water,
during a 24 hour period the correct number of cycles are delivered, so
that the clocks are correct at 8am. I'm not sure that they always
achieve this!
--
Ian

On Tue, 8 Mar 2011 20:34:49 +0000, Ian Jackson wrote:

I was surprised to see how low the voltage sometimes went (right down to
the minimum limit). When it was really cold over Christmas and New Year,
I expect the guys at the power stations were shovelling coal for all
they were worth, and that the frequency (which is of less interest than
the voltage) was well down on normal.

The frequency is very important, it's maintained at 50Hz +/- 1% ie
49.5 to 50.5 Hz nut National Grid work to an operational limit of +/-
0.4% (+/- 0.2Hz).

Obviously, any type of clock which uses the mains frequency will run
fast or slow if the frequency varies. My understanding is that the
generating people are supposed make sure that, come hell or high water,
during a 24 hour period the correct number of cycles are delivered, so
that the clocks are correct at 8am. I'm not sure that they always
achieve this!

Oh they do! Questions get asked in the house if they don't. IIRC the
last time they had to announce that mains driven clocks had the wrong
time and would need to be corrected was during the winter of 1947...

--
Cheers
Dave.

In article 3bb8952f-1316-4b1a-aaee-a773ee2fe244
@v31g2000vbs.googlegroups.com, says...
but did the frequency go down with the volts? I have a far eastern
LED Lloytron clock that seems to sync to the mains. If the frequency
goes down the clock runs slow.

Almost all LED clocks are mains synched. Since they have to be mains
powered anyway (yeah, mostly) then they're already connected to a well
regulated (by statute) frequency source.

As it happens, I have an exception, an LED clock that uses the RDS data
to set the time, though in the absence of decent reception it seems to
cope tolerably - presumably off the mains frequency or a crystal.

--
Skipweasel - never knowingly understood.

On Tue, 8 Mar 2011 10:27:33 +0000, Ian Jackson wrote:


Before Christmas, the typical 'normal' voltage was 230V, occasionally
going up to 235. However, when the really cold weather started, after
around 5pm, the voltage would start to drop and, on several days,
regularly fell to 215V. The lowest (checked on a couple of digital
meters) was 214.4V.

Routine load shedding, it's been happening for decades. 5% then 10% load
shed, acheived by a voltage reduction, I'll let you work out the percentage
reduction in voltage to get the reduction in load.

After that it's rota disconnection as happened in the 1970s.


--
The Wanderer

Computers are incredibly fast, accurate, and stupid;
humans are incredibly slow, inaccurate and brilliant;
together they are powerful beyond imagination.

The Wanderer wrote:
On Tue, 8 Mar 2011 10:27:33 +0000, Ian Jackson wrote:


Before Christmas, the typical 'normal' voltage was 230V, occasionally
going up to 235. However, when the really cold weather started, after
around 5pm, the voltage would start to drop and, on several days,
regularly fell to 215V. The lowest (checked on a couple of digital
meters) was 214.4V.

Routine load shedding, it's been happening for decades. 5% then 10% load
shed, acheived by a voltage reduction, I'll let you work out the percentage
reduction in voltage to get the reduction in load.

After that it's rota disconnection as happened in the 1970s.


Yep. Think of the grid as a huge generators to which lots of little
engines are geared. As demand goes up the voltage and frequency start to
fall..the whole contraption is 'climbing a hill'

Throttles are opened on all the engines online, and new ones are geared
to it to help a bit. Meanwhile the word goes out for anyone who can do
without the grid to get off it, and if anyone has any backup power units
spare, could they please start them..


If the whole shebang cant make it over the top, then passengers are
thrown out till it can.

You will get far more familiar with this as more silly wind power is
added to the grid.

On Thu, 10 Mar 2011 11:31:59 +0000, The Natural Philosopher wrote:

You will get far more familiar with this as more silly wind power is
added to the grid.

I'm not overly keen on this frequency based automatic load shedding
(as in switching off) either. Sounds like a recipe for grid
instabilty if you ask me. Frequency drops, lots of stuff drops off
line, Whe Hey! too much capacity frequency goes up, stuff comes back
online, frequency drops...

And how much stuff is about that can be switched off for an
indeterminate period without warning? Not a lot, storage heaters
maybe but they aren't on when there is peak demand and you could only
switch 'em off for a limited period otherwise people would be
cold(er) the next evening.

Some form of dynamic load directly controlled by the grid would work
but I'm skeptical about an open loop system.

--
Cheers
Dave.

On Tue, 08 Mar 2011 09:09:02 +0000, MM wrote:

I believe someone was recently talking about voltage spikes, though I
can't find the thread in Google Groups to hang this on. I happened to
be watching my consumption thingy this morning and noticed that it was
constant at 249 volts. Then it went up to 250 for 30 seconds, back
down to 249, then back up to 250 again. For a good five minutes it
hovered around 249-250. Then it came down to 248, then 247.

So only 3v change, depending on the quality of you supply you may
well get a bigger fluctuantion when you drop a decent load on, say
5kW or more.

Aren't these spikes damaging to sensitive equipment? (TVs, DVD Players
etc) I don't worry about the PC because I have a UPS on it. The
voltage is ~supposed~ to be 240 in the UK.

They aren't spikes just norm fluctuation caused by local load
variations, either in your imdeiate vicinty or in your home. The
nominal UK voltage hasn't been 240v for years. See other post. Note
that the "harmonised" range covers the old 240v spec so nothing had
to change. The only comment I'd make about the voltage sitting at 250
odd is that incandescent light bulbs will have a much shorter life.

We used to get through 40W candles in the living room (6 in use
18hrs/day) at about one per month and other odd 60W bulbs at several
a year. Bought a UPS plugged it in and it went straight into "voltage
trim" mode I thought it was faulty! Measured the volts up at 250 or
so, reported it, men arrived in a couple of hours confirmed the
reading and came back a day or two later to adjust the tapping on our
transformer. Voltage now sits between 235 and 245 (was 245 to 255)
and incandescent light bulbs last "forever".

The post about voltage variation was probably mine from the 3rd March
wondering if the grid had had a problem as our volts had risen to 253
for quite long periods overnight 2nd/3rd. Since then things have been
with the normal 235 to 245 range.

--
Cheers
Dave.

On Tue, 08 Mar 2011 10:08:39 +0000 (GMT), "Dave Liquorice"
wrote:

The post about voltage variation was probably mine from the 3rd March
wondering if the grid had had a problem as our volts had risen to 253
for quite long periods overnight 2nd/3rd. Since then things have been
with the normal 235 to 245 range.

Last time I looked (ten minutes ago) the read-out was reading 248v.

MM

On Mar 8, 9:09*am, MM wrote:
I believe someone was recently talking about voltage spikes, though I
can't find the thread in Google Groups to hang this on. I happened to
be watching my consumption thingy this morning and noticed that it was
constant at 249 volts. Then it went up to 250 for 30 seconds, back
down to 249, then back up to 250 again. For a good five minutes it
hovered around 249-250. Then it came down to 248, then 247.

Aren't these spikes damaging to sensitive equipment? (TVs, DVD Players
etc) I don't worry about the PC because I have a UPS on it. The
voltage is ~supposed~ to be 240 in the UK.

MM

A voltage spike is 100s of volts big, and lasts for milliseconds.

240v is the target voltage, real voltage can be 10s of volts away from
this. 1v variation isn't an issue.


NT

Tabby wrote:
On Mar 8, 9:09 am, MM wrote:
I believe someone was recently talking about voltage spikes, though I
can't find the thread in Google Groups to hang this on. I happened to
be watching my consumption thingy this morning and noticed that it
was constant at 249 volts. Then it went up to 250 for 30 seconds,
back down to 249, then back up to 250 again. For a good five minutes
it hovered around 249-250. Then it came down to 248, then 247.

Aren't these spikes damaging to sensitive equipment? (TVs, DVD
Players etc) I don't worry about the PC because I have a UPS on it.
The voltage is ~supposed~ to be 240 in the UK.

MM

A voltage spike is 100s of volts big, and lasts for milliseconds.

240v is the target voltage, real voltage can be 10s of volts away from
this. 1v variation isn't an issue.


I'll second that and just add that unless all the supply cables are
superconductors then the voltage will vary according to the load in both MMs
house and neighbouring houses.

MM - It is not unusual for the voltage to drop by as much as 8 volts in a
house when an electric shower is switched on depending upon the external
resistance of the supply to the house.


--
Adam

On Tue, 8 Mar 2011 17:42:09 -0000, "ARWadsworth"
wrote:

Tabby wrote:
On Mar 8, 9:09 am, MM wrote:
I believe someone was recently talking about voltage spikes, though I
can't find the thread in Google Groups to hang this on. I happened to
be watching my consumption thingy this morning and noticed that it
was constant at 249 volts. Then it went up to 250 for 30 seconds,
back down to 249, then back up to 250 again. For a good five minutes
it hovered around 249-250. Then it came down to 248, then 247.

Aren't these spikes damaging to sensitive equipment? (TVs, DVD
Players etc) I don't worry about the PC because I have a UPS on it.
The voltage is ~supposed~ to be 240 in the UK.

MM

A voltage spike is 100s of volts big, and lasts for milliseconds.

240v is the target voltage, real voltage can be 10s of volts away from
this. 1v variation isn't an issue.


I'll second that and just add that unless all the supply cables are
superconductors then the voltage will vary according to the load in both MMs
house and neighbouring houses.

MM - It is not unusual for the voltage to drop by as much as 8 volts in a
house when an electric shower is switched on depending upon the external
resistance of the supply to the house.

When I first observed the 250v this morning there was only the PC on.

MM

MM wrote:
On Tue, 8 Mar 2011 17:42:09 -0000, "ARWadsworth"
wrote:

Tabby wrote:
On Mar 8, 9:09 am, MM wrote:
I believe someone was recently talking about voltage spikes,
though I can't find the thread in Google Groups to hang this on. I
happened to be watching my consumption thingy this morning and
noticed that it was constant at 249 volts. Then it went up to 250
for 30 seconds, back down to 249, then back up to 250 again. For a
good five minutes it hovered around 249-250. Then it came down to
248, then 247.

Aren't these spikes damaging to sensitive equipment? (TVs, DVD
Players etc) I don't worry about the PC because I have a UPS on it.
The voltage is ~supposed~ to be 240 in the UK.

MM

A voltage spike is 100s of volts big, and lasts for milliseconds.

240v is the target voltage, real voltage can be 10s of volts away
from this. 1v variation isn't an issue.


I'll second that and just add that unless all the supply cables are
superconductors then the voltage will vary according to the load in
both MMs house and neighbouring houses.

MM - It is not unusual for the voltage to drop by as much as 8 volts
in a house when an electric shower is switched on depending upon the
external resistance of the supply to the house.

When I first observed the 250v this morning there was only the PC on.

And did you go and ask all the neighbours what they were using?

--
Adam

On Tue, 8 Mar 2011 18:16:14 -0000, "ARWadsworth"
wrote:

MM wrote:
On Tue, 8 Mar 2011 17:42:09 -0000, "ARWadsworth"
wrote:

Tabby wrote:
On Mar 8, 9:09 am, MM wrote:
I believe someone was recently talking about voltage spikes,
though I can't find the thread in Google Groups to hang this on. I
happened to be watching my consumption thingy this morning and
noticed that it was constant at 249 volts. Then it went up to 250
for 30 seconds, back down to 249, then back up to 250 again. For a
good five minutes it hovered around 249-250. Then it came down to
248, then 247.

Aren't these spikes damaging to sensitive equipment? (TVs, DVD
Players etc) I don't worry about the PC because I have a UPS on it.
The voltage is ~supposed~ to be 240 in the UK.

MM

A voltage spike is 100s of volts big, and lasts for milliseconds.

240v is the target voltage, real voltage can be 10s of volts away
from this. 1v variation isn't an issue.


I'll second that and just add that unless all the supply cables are
superconductors then the voltage will vary according to the load in
both MMs house and neighbouring houses.

MM - It is not unusual for the voltage to drop by as much as 8 volts
in a house when an electric shower is switched on depending upon the
external resistance of the supply to the house.

When I first observed the 250v this morning there was only the PC on.

And did you go and ask all the neighbours what they were using?

Well, no!

MM

Tabby writes:

240v is the target voltage, real voltage can be 10s of volts away from
this. 1v variation isn't an issue.

In fact, thanks to EU bureaucracy, isn't the target voltage now
230V +10% -6%, or some similar baloney which prevents any country from
actually having to change anything?

--
Windmill, Use t m i l l
@ O n e t e l
. c o m

On Fri, 11 Mar 2011 22:26:13 GMT, Windmill wrote:

In fact, thanks to EU bureaucracy, isn't the target voltage now
230V +10% -6%, or some similar baloney which prevents any country from
actually having to change anything?

It doesn't *prevent* any country changing anything, it just means
they don't *have* to change anything.

It was going to alter again to 230 +/- 10% but that puts the lower
limit down to 207 and a nearly 50v range. Starting to get hard to
build kit that will work satisfactorily at the lower end and not blow
up at the upper. That proposed change seems to have been quietly
dropped. B-)

--
Cheers
Dave.