Continental europe having problems with 50Hz

[The Other Mike]

Isolating the grids into separate frequency regions is useful with a relatively weak connection but it's not just for system stability and frequency purposes, the losses are lower and above all you have the ability to alter power transfer. If the UK agrees with France for a 500MW export from our end that is nothing more than a few key presses away. They can set a specific export level almost regardless of the prevailing conditions on the AC network with small balancing adjustments in the order of 10's of MW's easy to make. The effect of that transfer will be to make the UK frequency and voltage to drop and the continental frequency and voltage to rise. That will be corrected by the generator governors responding throttling back the continent and raising in the UK.

Reverting to a fully floating state and reversing flow without physically breaking the connection is also extremely rapid.

That transfer adjustment can be done on an AC network with quadrature boosters, but then the losses end to end would be significantly higher and there would be no separation of frequency region.

The original link built back in the 60's did, the 2GW link from the 80's uses thyristors. Fully updated and refitted a few years ago with a new control scheme and uprated power electronics.

[Martin]

Continental electric clocks are showing 5 minutes slow, but still 55 minutes ahead of UK :-)

[The Natural Philosopher]

Yes. The propagation delay across the USA mandates that at 60Hz you really dont wannna be THAT big..ortherwise your i8nphasde geretair is out of phase at the other side of the country.

I suspect that the European grid may yet fragment a little more into chinks with DC interconnectirs.

about 2000km is as big as I think you want to be

[Tim Streater]

phase generator ??

[Terry Casey]

Ah yes, I remember them well - bit our mains driven Smiths Sectric clock was always right to the second at 8am the following day!

[Dave Plowman (News)]

I've just adjusted my mains locked large LED digital clock by a minute - for the second time this year. First time I've had to bother - except when the hour changes.

[Johnny B Good]

Hum bars would have only become apparent with the advent of colour TV broadcasting which started mid 1967 in the UK. Prior to that, the monochrome broadcasts (both 405 and 625 line) were locked to the national grid.

I remember admiring the frequent adjustments being made (about every 15 seconds or so) by the national grid when watching the barely perceivable hum bars roll up and down the mid grey, "after hours" raster display on our TV set in the late 70s when it was obvious the master power station (s) was (were) being controlled from a crystal/atomic clock reference source to retain the grid's state of hard won resynchronisation with 'real time' during the wee small hours.

[charles]

I'm pretty sure the BBC went off mains lock once BBC2 turned up.

[Marland]

Andrew Gabriel

Germany and Austria also have a separate grid to distribute power for their railways,due to the electrification commencing in the 1900?s and the characteristics of motors of the era a low frequency of 16 and two thirds was adopted. This low frequency is also used in Switzerland and Scandinavia but they tend to generate from nearby hydro or convert from the 50hz grid where required.

GH

[Max Demian]

They must have 'normous transformers.

[Dave Plowman (News)]

Not so. They went off mains lock some time before colour. I think it may have been not long after BBC2 started.

[Johnny B Good]

Interesting, I wasn't aware that they'd divorced the system from the mains frequency ahead of time. Prior to the start of actual colour broadcasting, the 625 line system could have remained locked to the national grid frequency. It was only when the PAL colour system came into use that they were obliged to synchronise everything to the colour burst frequency and run independently of the national grid reference which was no longer stable enough in the short term to be of any use in the PAL system.

Presumably, this change was implemented early on in readiness for colour transmissions, perhaps to ease the final transition to a system that could no longer be locked to the mains frequency.

[Andrew Gabriel]

3 times the size, and they have to be carried by the train.

However, they couldn't make large powerful motors which ran on 50Hz at the time, because the winding inductance would be too high to get the necessary power in without the windings having to operate at voltages which winding insulation couldn't withstand.

[Dave Plowman (News)]

It may have been to do with the increasing use of outside broadcasts and so on as inserts to programmes. Think things like Nationwide. Where those might use their own generator or battery supply. You could lock the studio to a pulse generator anywhere, allowing pictures to be mixed between the two. Terms like genlock and natlock were bandied about at the time. And of course a VTR needs a stable 50 Hz reference too. Which mains simply isn't.

If a VTR is locked to mains, its playing time will vary with that mains frequency. Not exactly ideal.

[Max Demian]

They could have used DC generation, or rectified the AC (if there were suitable rectifiers in those days).

[tabbypurr]

16Hz is better able to overcome stiction due to its (physically) pulsing na ture.

NT

[Dave Plowman (News)]

They'd just nick the car instead...

[tabbypurr]

the majority of uk burglaries are hot prowl

NT

[Max Demian]

I thought electric trains connect(ed) their motors in parallel mode to start off, which is why they always (used to) start with a jerk.

[James Wilkinson Sword]

Too traceable, and insured anyway.