Sunday, February 13, 2005

Where were you when the lights went out?

There is an interesting paradox in the UK regarding our infrastructure. The electricity distribution network is totally reliant on telecommunications, whilst the telecommunications network is reliant on electricity. BT et-al can keep the phone network going without the mains as long as their diesel supplies hold up but the reverse is not entirely true.

It is to do with power stations coming on and off line. They have to join the national grid in a very controlled manner and will conversely dip out at the slightest sign of trouble as running on the grid out of sync can be very expensive indeed in new switchgear, generators and turbine halls. The electricity grid providers expect a very fast response over their private comms circuits, typically propagation delays of no more than 10mS. They got it on the original analogue circuits and it was retained when they were moved onto digital circuits running on the then new PDH hierarchy subsequently superceded by SDH.

There is a rather big fly in the ointment, however, in the form of BT's forthcoming 21st Century network, it seems it isn't suitable for 20th century power generation as the latency on the new asynchronous IP solution will be no better than 40mS. It also seems that the obligation to provide a guaranteed latency figure has been forgotten about in the mists of time. So, it seems to be a bit of a stalemate then and we can expect the introduction of BT's new solution to be a little problematic.

I asked my well informed colleague whether there were actually plans in place to bring up the national grid in the event of total shutdown. It seems that they do exist at a regional level. How long would it take? About a week.....

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