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Old 8th Mar 2018, 6:09 am   #51
Radio Wrangler
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Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 12,611
Default Re: Electric clocks running slow warning

Quote:
Originally Posted by Nymrod121 View Post
There were three sets and it had to be 'got right' on the Synchroscope - any discrepancy and the relevant set's ACB would trip ... followed by remedial action which included the duty Senior Tx Eng promptly adminstering a firm kick up the TE's backside
[Best quality 'uddersfield accent: ON]

Eeeee! Tha had a proper synchroscope, not just three light bulbs? Luxury, lad!

For those that don't already know, you can see grid frequency, loading and sources data here:

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

The national grid is completely synchronised (except for a major disaster scale fault) so a mechanical analogy would be a drive shaft connecting all generators and all loads. If generation can't make the load demands, the RPM (frequency) drops, and consequentially the voltage drops which gives less power to SOME loads. Low frequency triggers some spare generating capacity into action, much lower frequency and more expensive generators are brought on-line. The grid frequency is both an indicator of the availability versus demand balance, and it is the command structure.

Switch-mode PSUs in loads don't reduce power demand when the supply voltage falls, they increase demanded current to compensate. This increases ohmic losses, drops their supply volts a bit and then compensate for that with even more current demand, so their power demand increases with falling supply volts, creating a destabilising influence.

The drive for energy saving has meant more SMPS, more 'smart motors' and has given us a less-stable network, add in wind fluctuations and the quality of our supply is less than it used to be.

David
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