Low mains voltage

[28XX]

Unless I'm missing something that tells us what a voltmeter is, as if we didn't know already, but doesn't tell us how to go about measuring one's domestic supply? Are you sticking the device shown into your 13amp sockets? Methinks not.

That's exactly what you do. But safer to make it via a fixed, insulated connection between your multimeter and a fused plug.

[Titan]

No Martin, it isn't. A device with a specific power rating will consume more current when the voltage drops. P=U/I so a 1kW apparatus will consume 4.14Amps on 239V, while at 216V it saps 4.63 Amps from the National Grid.

 

 

???

 

For a simple resistive heating element the curve is not a straight line, but the gradient doesn't go negative. More volts = more amps, regardless of the element temperature. Here is the curve for a lamp filament:

 

 

Martin.

 

You are both right, sort of. Dutch Masters mistake was implying (probably not intentionally) that all devices rated at a specific voltage will take more current at a lower one. Some will, some won't. If a device has a specific rating at a specific voltage, that is exactly what it will do at that particular voltage, It is by itself no guide as to what the performance will be at other voltages. Another example is an induction motor. It's rpm is dependent on frequency. If the voltage drops but the frequency remains the same, it will still turn at the same rpm and give the same torque, but the current drawn will go up. The current could get high enough to burn it out, despite it running at normal speed and load. However the majority of domestic motors will be of the series wound or universal type, which would just run more slowly and take less current, even if they had exactly the same rating at the same voltage as the induction motor. Purely resistive loads power will drop. Other electronic equipment may vary.

[ZiderHead]

Are you sticking the device shown into your 13amp sockets?  Methinks not.

 

Only if you know what you're doing, and only if your meter and test leads are at least CAT III rated. 

[martin_wynne]

Purely resistive loads power will drop.

 

Which represents the vast majority of domestic power consumption.

 

Martin.

[Budgie]

Watts = Volts X Amps.

That's only true if the voltage and current are in phase. That's why you see the abbreviation VA used.

 

See https://en.wikipedia.org/wiki/AC_power

[martin_wynne]

1am and it's back to 236V.

 

Not a good day for National Grid, bearing in mind that we are only in the first week of November and the weather is mild.

 

"National Grid earlier issued a Notification of Inadequate System Margin (NISM) ... The company last issued a NISM in February 2012, and before that in 2009."

 

Martin.

[martin_wynne]

IIRC there's at least one high voltage link to the Continental grid, so purchase of power elsewhere shouldn't be too much of a problem, provided said link(s) can handle the extra load.

 

And provided they have some to spare in mid-winter. I'm not clear why we should be relying on our neighbours to bail us out.

 

Martin.

[Nearholmer]

Does seem a very strange time of year, and exceedingly mild weather, to be getting into these issues.

 

I wonder if there are a lot of scheduled plant outages right now for "pre-winter" maintenance, and that the planning-assumptions were that there would be more from wind than has been the case for the past few days.

 

Clearly getting rather tight, though.

 

K

[Pannier Tank]

Only if you know what you're doing, and only if your meter and test leads are at least CAT III rated.

 

and not forgetting to use GS38 Fused Test Leads.

[Austrag]

You don't need to worry too much at 216 volts, In the last week here we have suffered three power cuts, twice around mid afternoon and the last at 2.30 AM. The ensueing mayhem with alarms sounding was a real shock to my system and added to the buggeration factor of resetting appliances in the morning.

[Clive Mortimore]

Does seem a very strange time of year, and exceedingly mild weather, to be getting into these issues.

 

I wonder if there are a lot of scheduled plant outages right now for "pre-winter" maintenance, and that the planning-assumptions were that there would be more from wind than has been the case for the past few days.

 

Clearly getting rather tight, though.

 

K

As I stated earlier in this thread, those of us who live in the UK might have noticed the lack of wind and how cloudy/foggy it has been. No wind generation and the extra demand on lighting a dull day makes have been contributors to the problem. The closure of base load coal power stations with no replacements may not helped as well.

[kevinlms]

Does seem a very strange time of year, and exceedingly mild weather, to be getting into these issues.

 

I wonder if there are a lot of scheduled plant outages right now for "pre-winter" maintenance, and that the planning-assumptions were that there would be more from wind than has been the case for the past few days.

 

Clearly getting rather tight, though.

 

K

The different type of electricity plants, have different times required to generate more electricity on demand. My understanding is that thermal plants such as coal, require a day or so to fire up & become operational. At the other end, plants like hydro-electric & be turned on very quickly, at very short notice.

 

https://en.wikipedia.org/wiki/Dispatchable_generation

[Sheffield]

Relying on the neighbors, Ireland and France, may be a short term fix, but if it is decided to have a divorce from the EU, and this divorce goes nasty as they often do they may not be willing to help. Lets hope the Chinese get a move on.

It is unfortunate that power generation on a national scale requires planning over a longer period than a parliament lasts, so does not happen sensibly.

[kevinlms]

And provided they have some to spare in mid-winter. I'm not clear why we should be relying on our neighbours to bail us out.

 

Martin.

Apparently common practice for European countries to help each other out. Even France which is largely dependent on nuclear, has problems in sudden cold/hot spells & relies on Germany, as their own system isn't flexible enough.

 

https://en.wikipedia.org/wiki/Nuclear_power_in_France

 

Australia doesn't have international neighbours to help out in times of peak! Only the Basslink from Tasmania,

 

https://en.wikipedia.org/wiki/Basslink

[Nearholmer]

Worrying about borrowing electricity from our immediate neighbours?

 

Er, aren't we seriously reliant upon various slightly sinister blokes who live about ten country's down the road for most of the fuel that goes into our own generating plants?

 

Enough to put the wind up you, especially when there's no wind up your wind-turbines, it is.

 

K

[APOLLO]

Tonight, at peak time (5pm to 7pm) have a look at this site.

 

http://www.ukenergywatch.org/Electricity/PowerStations

 

Filter out the non-coal power stations (untick the boxes to the right, leaving only coal ticked). Then Zoom in and have a look at each station in turn, especially the big ones Fiddlers Ferry (near Liverpool) and the big uns over in Yorkshire. You can see to the right under information the current generation along with the plants max capacity. Only Drax was near capacity last night, and that burns biomass (wood pellets) along with coal. Currently Drax is 3182 as against 3870 max as it was last night.

 

Fiddlers Ferry certainly is nowhere near capacity. 450mw current as against 1980 max as I type. The other Yorkshire stations (not Drax) are similar (nowhere near full capacity).

Like I said, have a look at peak tonight - I will.

 

We are being told pork pies re plants down due to tech problems. They are simply refusing to burn coal at the moment in my opinion. "Test run" for next year ?.

 

A couple of big ones will close next year, Longannet (Scotland), and Eggborough (Yorkshire) both next March. That's 2304 + 1960, Total 4264MW offline for good.

 

Brit15

[The Stationmaster]

Yes. Have a look at the National Grid real time frequency. A bit up and down at the moment. As far as I know the balance of ups (over 50Hz) and downs (under 50 Hz) needs to balance over a set time (whatever that is - anyone know ?).

 

http://www2.nationalgrid.com/uk/Industry-information/electricity-transmission-operational-data/

 

Another interesting site

 

http://www.gridwatch.templar.co.uk/

 

And a scary one

 

http://www.dailymail.co.uk/news/article-2810651/Will-lights-winter-Biggest-danger-power-blackouts-eight-years-forces-energy-bosses-consider-paying-factories-shut-down.html

 

Ex National Grid gas engineer myself. Stocking up on various things as said. I'm not joking, and hope we squeeze through the coming winter - but we WILL get caught out sooner or later.

 

Edited to add - I see coal is generating only around 25% of the national demand at the moment. Last winter it was consistently around 35 to 40%. Is the shutdown of coal plant hitting already ?. If so, god help us over winter.

 

Brit15

The problem is that the decision to replace the large coal fired stations should have been made 12 years ago but the politicians preferred to mess about with other things while at the same time subsequently agreeing that those stations would be gradually taken offline leaving no incentive to modernise many of them.

 

The situation now is that with changes in subsidies and taxes it is totally uneconomic to buy coal to make electricity and unless that changes coal fired plants will close just because they exhaust their coal stocks - already soem big generators are predicting they will close coal fired plant in the spring for that reason, if it is a very hard winter and demand rises the stations will close sooner.

[Nearholmer]

Kevinlms

 

Yep, its all about the mix of sources to match load at minimum cost, and that's where "planning assumptions" come in, and if the plan envisaged xxxMW of wind-source, at a, b, & c places, and wasn't revised quickly enough in the light of emerging weather forecasts, and/or some chunk of plant that was envisaged available in the plan went sick at short notice, or the plan always envisaged the possibility of having to apply " extreme measures", or if it was just a rubbish (overly risky) plan in the first place .........

 

As with many things we talk about here (model and real railways very definitely excepted) we are a tad short of facts.

 

Kevin

[jjb1970]

The grid already has pull back schedules in place to interrupt supplies to given consumers to protect the grid. That is a staggered program and if domestic supplies are interrupted then there really has been a catastrophic collapse of the supply side of the system. A lot of industrial consumers get significantly discounted supplies in return for being on an interruptible supply arrangement.

 

Energy policy has been a mess for many years and it isn’t helped by a planning process which increases the risks and costs of any potential new investment in power stations. And the attitude of the environmental lobby means that quite aside from the planning process few companies will go anywhere near coal with a bargepole in the UK in terms of new construction. My former employer planned two new coal units at Kingsnorth (Kingsnorth 5 & 6), they were to be super-critical units with full emissions abatement and planned for carbon capture and storage. If you listened to the eco lobby the plant was going to be the equivalent of Bhopal on the Thames and the political pressure meant that quite aside from planning considerations E.ON just walked away as it was not worth the heat. Keep in mind our foreign owned energy companies have no real reason to invest in the UK and if it is easier to invest in other countries then that’s what they’ll do.

 

I support clean energy and renewable energy. I think it is the future however there is a transition to a genuinely low carbon future during which we will still rely on other forms of power. And until we develop large scale energy storage systems or renewable technology which is not intermittent then we need a means of both regulating the system when the wind is blowing quite well (peak lopping) and also to provide the energy we need when we have periods where environmental conditions pull the floor from under the wind farms. And that means coal and gas realistically. Longer term I hope that new generation nukes will provide a sufficient buffer to maintain the system under anticipated perturbations. And then we find another example of the law of unintended consequence, in the current land scape fossil plants have to be flexible to go on and off line quickly and also operate at variable load when they are on line. With most fossil fuel power plants you can have flexibility or you can have efficiency but if you want flexibility you will suffer an efficiency penalty. So the effect of renewables is to lower the efficiency of fossil plants. For many years two shifting has been normal for many coal plants and CCGTs, technically they do it and it is not a problem however they are less efficient than they could be basically because of metallurgy. And then there is cost, if you want CCGT and coal plants available to support the grid in winter then somebody has to pay for them, they still need maintenance, fuel, staff etc. There used to be a few small fast response plants which were designed to dump a lot of power into the system quickly (a bit like pump storage) and damn efficiency, Taylor’s Lane in Willesden is one of these however again somebody has to pay for plants which are hopefully very rarely used.

 

With regards to Europe, keep in mind that the German system is a shambles as well thanks to their governments decision on nuclear plants and some of the other European systems aren’t that great either so relying on the interconnectors with Europe may not be such a good idea.

[Vanders]

Tonight, at peak time (5pm to 7pm) have a look at this site.

 

http://www.ukenergywatch.org/Electricity/PowerStations

 

Filter out the non-coal power stations (untick the boxes to the right, leaving only coal ticked). Then Zoom in and have a look at each station in turn, especially the big ones Fiddlers Ferry (near Liverpool) and the big uns over in Yorkshire. You can see to the right under information the current generation along with the plants max capacity. Only Drax was near capacity last night, and that burns biomass (wood pellets) along with coal. Currently Drax is 3182 as against 3870 max as it was last night.

I just took a look at one of my local nuclear plants (Hinkley B ) and the page shows it's currently generating 970MW...with a maximum of 860MW! I'm not sure how far I trust the data there...

[APOLLO]

On the gas side of things interuptable loads were never meant to be, or thought of as, "Extreme measures". Winter gas loads are mainly weather dependant, and when it gets cold gas demand rises and the loads are interrupted, no big deal, not even newsworthy. No one suffers as adequate alternatives are in place, as a condition of getting cheaper gas when gas loads are not critical (summer). Over many winters gas loads have been interrupted quite a number of times without any worry about domestic supplies. There again, engineers were in charge of the industry back then (even for quite a few years after gas privatisation in 1986).

 

Yesterdays "extreme measures" thing is very worrying seeing as its early November and the weather is mild. We have not had a significant frost so far. (Lancashire)

The "extreme" measures are meant to both shed loads (industrial) and buy in, at great expense, "spare" capacity. This spare capacity will decrease by a considerable margin next year when the coal stations mentioned close for good (not mothballed). If we scrape through this winter then 2016/17 will be a bigger worry.

 

As to renewable energy. Great if you can get enough.

 

How many windmills / solar panels does it take to replace a 2000MW coal fired power station, especially at 6pm on a still, freezing cold, dark winters night. THIS is THE

problem.

 

Then there is this. I can't comment regarding the ramifications of closure (as I simply don't know) - but it can't be good. Yes it's 40 years old and life expired, but again, I suspect it's just about not spending the money on replacement. Some interesting letters in the links.

 

http://www2.nationalgrid.com/UK/Services/LNG-Storage/consultation/

 

Brit15

[APOLLO]

I just took a look at one of my local nuclear plants (Hinkley B ) and the page shows it's currently generating 970MW...with a maximum of 860MW! I'm not sure how far I trust the data there...

 

Wait till it goes dark - an eerie green glow around the plant will account for the surplus !!!!!!!!!

 

Brit15

[martin_wynne]

As to renewable energy. Great if you can get enough.

 

How many windmills / solar panels does it take to replace a 2000MW coal fired power station, especially at 6pm on a still, freezing cold, dark winters night. THIS is THE

problem.

 

But this doesn't require sun or wind:

 

 http://www.bbc.co.uk/news/science-environment-31682529

 

Why haven't we been pushing ahead with these schemes all around the coast? Bearing in mind that the tides are utterly predictable: https://en.wikipedia.org/wiki/King_Canute_and_the_waves

 

Martin.

[APOLLO]

AND the UK has one of the highest tidal ranges in the world. From 4 metres (13.1 ft) neap tide to 10 metres (32.8 ft) spring tide, the River Mersey has the second highest tidal range in Britain – second only to the River Severn. The river Severn has the third highest tidal range in the world, only the bay of Fundy (north America) and Ungava bay ( Hudson straits) are bigger. The tidal range on the Severn can be as much as 15m (49ft), this combined to the 'funnel' shaped estuary causes the incoming tide to create the Severn bore.

 

All this energy, four times a day (twice in, twice out), and we are an Island with many suitable estuaries, Severn, Morecambe Bay etc.

 

Still, the towel folder knows better.

 

Brit15

[Fat Controller]

Wait till it goes dark - an eerie green glow around the plant will account for the surplus !!!!!!!!!

 

Brit15

Do power stations have a 'one-hour' rating, as some electric motors used to have?