Interesting reading from UPS

[Ian Jackson]

I was (obviously) using the loose, non-technical 'nominal'. However, in this case, these days, the actual voltage is almost always pretty close to nominal. The lowest I've ever seen (214V when the supply was understandably struggling a bit) is a smidgen out-of-spec (-6% =

216.2V). Mustn't grumble, I suppose).

Actually, I've just plugged in my ex-colleague's meter again, and I see it's nearly 235V. Previously, it's never exceeded 231V. Could it be, that at the power stations, even though the weather is unusually mild, they are making absolutely sure that they use up their allocated stocks of coal?

[The Natural Philosopher]

yes..the actual voltage SHOULD be around 230v but for legacy reasons its quite broad.

They will up the tap if a lot of power is being drawn..but some isntallations don't have taps..

[The Natural Philosopher]

well yes and no,, they are doing that, but mostly the power is being exported to the continent where unremitting Green policies seem to have resulted in a general shortfall.

What we are seeing though is a bit more voltage and frequency instability - the fast response balancer is Dinorwig, and I've seen that running flat out recently. That means they have to try and baalnce with CCGT - the coal stations CAN balance but take a significant period to ramp up and down.

[Andy Burns]

Mine's been high for years, a few months ago they turned to do some work on the substation at the top of the road, a BFO artic sized diesel generator arrived and thundered away for about 6 hours while they "did something".

When the work was complete I made a point of checking the before and after voltages from my UPS, thinking they might have adjusted the taps as part of the work ... still fluctuates between 249 and 254 over the course of a day.

[The Other Mike]

That might have been an aim, but mainly as a result of when it was feasible to do most of the catching up - overnight, with lower loads and an excess of generation.

10 seconds error needing to be corrected over 8 hours only needs 500 cycles extra , or a couple of 10ths of a hertz above 50 to catch up. That equates to running all the 2 pole generators at a bit over 3001 rpm rather than 3000, it takes a bit more fuel, but is trivial to achieve.

[John Rumm]

It sounds like your supply has been moved down a tap, or the loading conditions elsewhere on your phase have changed.

I am not aware of any policy to transition distribution to 230V though.

[Ian Jackson]

I think I'll have to amend my claim that, recently, my mains voltage had never risen above 231V (although this was certainly the case from January (when I first acquired the home-made meter) until September. However, as a result of me doing a bit of tidying up, and it's been unplugged for the last two months.

As a result of this thread, I plugged the meter in again. Yesterday evening, it was around 228V. But, later on, it rose to 235V, and it's still there this morning. [I'll check the reading on a 'proper' meter.] However, I suppose it's just possible that they might have tweaked the voltage up a notch.

[Nick Odell]

When I lived in the wilds of remote Cambridgeshire, my electrickery went through a phase (sorry!) of peaking at around 190v, measured with an analogue multimeter). When it got to a stage where some things were just not working properly, I called the electricity company and on investigation they found a corroded connection in the miles of cable that came over the fields to my house. After they fixed that, I got

240v with hardly any variation. I don't suppose that could be relevant to your experience, could it?

Nick

[Goalie of the Century]

In message , Mike Tomlinson writes

types of generation too.

[Ian Jackson]

In message , Nick Odell writes

Anything is possible, but I can't really say I have a problem. It's been sitting at a steady 235V all afternoon, but I now (5.30pm) I see it has now dropped to a somewhat 'wavery' 225V (occasionally kicking up and down by a couple of volts). Can't really complain about that! Having finished my tidying up, I'll now leave the meter plugged in, and keep an occasional eye on it again.