harry's dream comes true

[Tim Streater]

Gridwatch says we're now running on DC.

[Andy Burns]

Just as you post, all the needles (except frequency) jump back up ...

[Tim Streater]

Quite. The world obviously switched to DC during the night.

[Tim Watts]

Edison's come back and haunted TNP's server?

[Adrian C]

The needle is probably stuck?

I've tried tapping on the monitor screen to see it that makes a difference, but to no avail. Perhaps, if we all did it, it might move?

Or perhaps a medicinal squirt of WD-40 somewhere...

Or Scotch....

[The Natural Philosopher]

yep. someone rebooted BM reports SOAP server..or whatever it is.

[harryagain]

It's possible in the future that may happen.

Theoretically there could be big reduction in transmission losses. We need an electronic means of stepping DC voltages up and down.

Fault protection would be more difficult.

[ARWadsworth]

Well something has happened.

I have just got back from work to find the computer turned off (and it took ages to start up), the radio alarm clock was playing radio 2 but the time display was not flashing as happens after a power cut, the cctv has recorded continuously so that also suggests no power cut.

The battery powered clock and my watch have both stopped with 7.40 showing.

The CCTV has only one event list showing. That was the postman so no-one has come through the front door to bugger around with anything.

It must have been the switch back from DC to AC that caused it!

[Tim Watts]

It's very hard to beat the efficiency and simplicity of a big-arsed transformer so I'm feeling confident Tesla will not be proved wrong for a long time...

DC has its uses - when you cannot maintain phase (or frequency) lock.

That's an interesting one. The big AC fault breakers are already use oil of SF6 to quench/blow out the arc. I wonder if DC would be much of a challenge.

It makes a difference on low power kit where SF6, oil, etc are not available of course. sure Dave L could relate some Beeb related stories (they had DC power knocking around didn't they?)

[The Natural Philosopher]

Brownout

Not enough to take down the radio completely, but enough to take the computer down.

[The Natural Philosopher]

I remember going round the French interconmnector many years ago when it was still 'new'

"We can strike and hold an arc, off the disconnected cable, for 40 minutes" the man said.

DC is harder to switch. Arcs. AC breaks arcs.

[damduck-egg]

Look out for a big Robot called Gort.

G.Harman

[Andy Champ]

Seems to me a B***y great relay in a vacuum would help. Or would the arc run in vapourised contact?

Andy

[Tim Watts]

Metal ions...

[js.b1]

The largest losses are in LV not MV or HV, so if they were to go DC it would be for the LV network?

Disconnecting DC is hard because it is easier for an arc to establish (no AC cycle) and thus full fault current develop, whereupon metal contacts erode into toasty plasma.

SF6 is one very nasty substance too, definately one for the mother in law...

... talking of which, why is there no DIY guillotine construction on uk.d-i-y... or has the death of distance resulted in the death of effort, supplanting by the angle grinder?

[Andy Burns]

In what way? Plenty of videos of people inhaling it for the opposite of the Helium mickey mouse effect, granted the helium will tend to float up and out of your lungs where the SF6 will "pool" at the bottom of them unless you exhale it ...

[The Natural Philosopher]

yes.

[Dave Liquorice]

The last brown out we had confused the heck out of me. It started about 0400 and something woke me up, might have been the text arriving to tell me that the ADSL had gone off unexpectedly. The CFL lights worked but ordinary flourescents wouldn't even try to strike. The server, network switch and WiFi where still on but the ADSL modem wasn't happy nor the DECT phone. Having some things working normally, some badly and others not at all is *very* confusing when half asleep.

Dug out meter and the volts were down at 140. On the basis that 140v might not be liked, as in hot and smelly and being half asleep. I tripped most of the MCBs leaving just one ring on with a table lamp and very dim tungsten bulb. Power finally disappeared about 0930 and was off for the next 30 hours as they replaced the broken poles and repaired the lines brought down by icing.

[The Other Mike]

The gas is near harmless apart from asphyxiation. After it has been exposed to arcing then there are fluorine compounds formed that are not particularly friendly to humans.

A significant proportion of breakers on the supergrid system use compressed air as the operating, insulating and spark extinguishing medium. Some on the 275kV network are oil filled but are rapidly being replaced as soon as they come close to the end of their service life. The risk of oil leaks is too high. Just about all that have been fitted in the past 20 years or so have been SF6 - the first ones in the UK being installed in the mid to late 1970's.

[The Other Mike]

Vacuum breakers on do exist on AC distribution networks.