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Post by tubeprune on Jun 23, 2022 16:37:38 GMT
I noticed that a number of S Stock trains reported: "Correct Operations Protection" (COP) issues yesterday after a power surge at West Ham. Can anyone tell me what this COP is? Is it to do with downstream circuit breaker reactions to traction supply faults?
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Post by t697 on Jun 23, 2022 17:08:19 GMT
Correct Operation Protection.
It's the S stock and 09TS signalling interference detection/protection. Monitors for different frequencies, threshold signal levels and durations across a programmed spectrum. Any exceedance above a programmed threshold and the High Speed Circuit Breakers for that shoegear car are opened, isolating the equipment from the traction supply.
Unfortunately such devices can't tell the difference between train generated interference caused by a train fault and traction supply carried interference such as in a power supply surge or other event.
There is work in progress to address the recurring issue in this area, including plans for desensitising the COP at a particular frequency that isn't relevant to signalling. All as I understand it, others may be along to correct this.
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Post by Dstock7080 on Jun 23, 2022 17:16:47 GMT
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Colin
Advisor
My preserved fire engine!
Posts: 11,349
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Post by Colin on Jun 23, 2022 20:37:38 GMT
It's the S stock and 09TS signalling interference detection/protection. Monitors for different frequencies, threshold signal levels and durations across a programmed spectrum. As a driver of S stock, its news to me that it monitors signalling frequencies! Maybe it's a lack of knowledge on the part of those that deliver our training but drivers are trained that the COP simply monitors the traction current supply onto the train and it'll throw its toys out of its pram if there's a spike above a predetermined level. We have a button in the train cab called ice mode and we've been trained that it relaxes the parameters of the COP during icy conditions when the traction current is liable to be "more spikey". Ice Mode has been tried to mitigate the recent issues but was found to be ineffective. An internal update bulletin was put out this evening and that blames the current issue squarely on Network Rail traction current supplies adjacent to the District line. My understanding is that the S stock trains/COP are being affected by very high voltages present in the positive rail. |
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Post by jimbo on Jun 23, 2022 21:33:52 GMT
Why is this happening after ten years in service? What has changed?
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Post by t697 on Jun 23, 2022 21:41:40 GMT
Why is this happening after ten years in service? What has changed? It appears that there have been changes on the supply side. I've heard it speculated that the reduction in traditional huge coal fired power stations and increase in individually smaller generators such as wind and solar may be relevant. |
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Post by tubeprune on Jun 24, 2022 5:18:43 GMT
Correct Operation Protection. It's the S stock and 09TS signalling interference detection/protection. Monitors for different frequencies, threshold signal levels and durations across a programmed spectrum. Any exceedance above a programmed threshold and the High Speed Circuit Breakers for that shoegear car are opened, isolating the equipment from the traction supply. Unfortunately such devices can't tell the difference between train generated interference caused by a train fault and traction supply carried interference such as in a power supply surge or other event. There is work in progress to address the recurring issue in this area, including plans for desensitising the COP at a particular frequency that isn't relevant to signalling. All as I understand it, others may be along to correct this. Very interesting, thanks for this. I always understood that the track circuit frequency had to be modified to avoid problems with traction interference and that 125Hz was the preferred supply frequency. So this is a sort of 'belt and braces' approach? |
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Post by tubeprune on Jun 24, 2022 5:32:58 GMT
Interesting that it has been going on for so long. And that it's not confined to just one traction section. Then, one has to ask, if it is connected with high positive rail voltage, why don't the sub-station breakers open? And, what has this to do with the COP which seems to be to do with frequency protection? Forgive me, as my understanding of electricity supplies is at Apprentice level -1 but I'm trying to get to grips with it because of my writing a series on the history of LU signalling. |
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Post by t697 on Jun 24, 2022 13:16:44 GMT
Very interesting, thanks for this. I always understood that the track circuit frequency had to be modified to avoid problems with traction interference and that 125Hz was the preferred supply frequency. So this is a sort of 'belt and braces' approach? The COP monitors for all relevant signalling frequencies and their associated safety thresholds. You are correct that 33 1/3 Hz track circuits were removed as part of the original infrastructure preparations for S stock. In some places this was by 125Hz replacement but in other places different track circuit types were used. |
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Post by zbang on Jun 24, 2022 16:33:52 GMT
I've heard it speculated that the reduction in traditional huge coal fired power stations and increase in individually smaller generators such as wind and solar may be relevant. I'm not sure that passes the engineering "sniff test". Yes, fossil plants use rotating machines and wind/solar use inverters, and they latter can generate multiple harmonics in the output, but generally only the fundamental freq should survive transmission of more than a few KM at the outside. AFAIK large-scale inverter facilities try hard to keep the higher harmonics from escaping their plant.
If electrical noise is getting in to the traction power, it pretty much either has to get in through the rectifiers/converters or be induced by local sources.
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Post by d7666 on Jun 24, 2022 18:59:10 GMT
I've heard it speculated that the reduction in traditional huge coal fired power stations and increase in individually smaller generators such as wind and solar may be relevant. I'm not sure that passes the engineering "sniff test". Yes, fossil plants use rotating machines and wind/solar use inverters, and they latter can generate multiple harmonics in the output, but generally only the fundamental freq should survive transmission of more than a few KM at the outside. AFAIK large-scale inverter facilities try hard to keep the higher harmonics from escaping their plant. If electrical noise is getting in to the traction power, it pretty much either has to get in through the rectifiers/converters or be induced by local sources.
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Post by Chris L on Jun 24, 2022 19:39:57 GMT
Why is this happening after ten years in service? What has changed? It appears that there have been changes on the supply side. I've heard it speculated that the reduction in traditional huge coal fired power stations and increase in individually smaller generators such as wind and solar may be relevant. I wonder what is happening with the updating of Greenwich Power Station with the aim of supplying most of the power to the Underground? |
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Post by AndrewPSSP on Jun 24, 2022 22:30:21 GMT
Is LU going back to in-house electricity supply?
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