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East Croydon Area Power Surge Yesterday

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East Croydon Area Power Surge Yesterday 19/12/2019 at 18:25 #122346
Edgemaster
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Network Rail have produced a good write up of what went wrong with yesterday's signalling systems failure in the East Croydon area, which simultaneously took out 4 interlocking areas. A power surge lasting 20s tripped out various different control systems in each interlocking resulting in all signals in the area reverting to danger and systems requiring manual reset.

https://www.networkrail.co.uk/running-the-railway/our-regions/southern/disruption-at-victoria-and-london-bridge/

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East Croydon Area Power Surge Yesterday 20/12/2019 at 08:23 #122357
JWNoctis
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Not directly relevant, but I'm being reminded of this article on 1930's third-rail electrification, power frame, and the Brighton Belle:

https://www.railwaywondersoftheworld.com/electric-power-grand-scale.html

I wonder, but honestly have no idea, what 20s of power surge would have done in those times, or later during the PSB era.

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East Croydon Area Power Surge Yesterday 20/12/2019 at 09:05 #122358
kbarber
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JWNoctis in post 122357 said:
Not directly relevant, but I'm being reminded of this article on 1930's third-rail electrification, power frame, and the Brighton Belle:

https://www.railwaywondersoftheworld.com/electric-power-grand-scale.html

I wonder, but honestly have no idea, what 20s of power surge would have done in those times, or later during the PSB era.
Nuffink guv. An L frame or a K frame wouldn't notice, I doubt that a surge would be enough to harm any lamps and the relays would be pretty much unaffected as well. And the trains wouldn't worry either; good old fashioned contactors & starting resistances would likewise be unaffected, though a driver might notice his train performing a littl ebetter than usual.

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East Croydon Area Power Surge Yesterday 20/12/2019 at 13:41 #122363
Edgemaster
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It's interesting to note that the NR article didn't specify by how much the supply voltage was over the nominal value, I wonder how much tolerance the various equipment transformers have?

Quote:
I wonder, but honestly have no idea, what 20s of power surge would have done in those times, or later during the PSB era.
The interlockings impacted are in the PSB era. Three of the four noted are freewired or route relay interlockings controlled by TDM from Three Bridges ASC. The report notes that the TDM (telecoms) equipment had its power supply tripped. The fourth interlocking that failed at Streatham was resignalled in 2016 with a computer based interlocking and recontrolled at the same time from Victoria ASC to Three Bridges ROC.

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East Croydon Area Power Surge Yesterday 20/12/2019 at 16:33 #122366
clive
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It all comes down to what kind of protection you have on the front end of your power supply. From memory, the Farnley Junction fatal collision in the ?1970s was partly due to power supply surges.

A computer-based system is more likely to have good protection because it's more sensitive. In many cases, the Uninterruptable Power Supply you put there to deal with unexpected power cuts also does a good job of regulating the supply.

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East Croydon Area Power Surge Yesterday 21/12/2019 at 12:47 #122379
slatteryc
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I've not seen the south London rail network knocked out so comprehensively in a very long time
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East Croydon Area Power Surge Yesterday 23/12/2019 at 00:58 #122392
JWNoctis
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Most interesting, thanks.

It's kind of...I don't know, terrifying? That they apparently did not have failover on overvoltage in their power supply, even though overvoltage and power surge is normally very uncommon these days.

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