🧵1/n
Further to my blog post yesterday (link in thread), a little more info about the incident at North Hyde substation which triggered the Heathrow shutdown.
The failed transformer was ~60 years old, installed in the 1960's. It tripped out on operation of a "Buccholz" relay.
Further to my blog post yesterday (link in thread), a little more info about the incident at North Hyde substation which triggered the Heathrow shutdown.
The failed transformer was ~60 years old, installed in the 1960's. It tripped out on operation of a "Buccholz" relay.
2/n
A Buccholz relay detects gas in the insulating/cooling oil, formed when it begins to break down under heat. It will also detect surges of oil in the conservator tank - an expansion chamber at the top of the transformer to cater for normal temperature related volume changes.
A Buccholz relay detects gas in the insulating/cooling oil, formed when it begins to break down under heat. It will also detect surges of oil in the conservator tank - an expansion chamber at the top of the transformer to cater for normal temperature related volume changes.
3/n
The failure was apparently sudden - no earlier warning alarms before the trip.
Faults like this are "seen" by many protection components across the network, which act to isolate circuits, try auto-reclosures etc. Obviously the transformer failure was terminal.
The failure was apparently sudden - no earlier warning alarms before the trip.
Faults like this are "seen" by many protection components across the network, which act to isolate circuits, try auto-reclosures etc. Obviously the transformer failure was terminal.
4/n
I would expect the investigation & report to focus on a few issues.
1. What caused the initial failure?
Obviously the age & maintenance history of the transformer will be in the spotlight. Other than on-load tap changers, transformers are essentially static devices.
I would expect the investigation & report to focus on a few issues.
1. What caused the initial failure?
Obviously the age & maintenance history of the transformer will be in the spotlight. Other than on-load tap changers, transformers are essentially static devices.
5/n
They do "vibrate" though from hysterisis - hence the characteristic hum.
2. Did the protection systems perform properly?
There are many potential points of failure, each should be covered.
3. The basic design/layout of the transformer bays at North Hyde.
They do "vibrate" though from hysterisis - hence the characteristic hum.
2. Did the protection systems perform properly?
There are many potential points of failure, each should be covered.
3. The basic design/layout of the transformer bays at North Hyde.
6/n
The close proximity of transformers & lack of concrete separation barriers. The adequacy of fire protection systems etc.
4. Why was this old, non-standard kit still in service?
How far advanced was work to upgrade the 66/22 kV network to 132/33 kV. Was finance a factor.
The close proximity of transformers & lack of concrete separation barriers. The adequacy of fire protection systems etc.
4. Why was this old, non-standard kit still in service?
How far advanced was work to upgrade the 66/22 kV network to 132/33 kV. Was finance a factor.
7/n
All the necessary information should be readily available to genuine experts. The report should take a matter of days - but you can bet it will be far longer.
However, we 𝗮𝗹𝘀𝗼 need a comprehensive report into the woeful failures at Heathrow itself.
All the necessary information should be readily available to genuine experts. The report should take a matter of days - but you can bet it will be far longer.
However, we 𝗮𝗹𝘀𝗼 need a comprehensive report into the woeful failures at Heathrow itself.
8/8
This incident should not have shut down the airport. There is redundancy in the supply arrangements, & Heathrow should have been able to weather the loss of a single intake substation without significant disruption.
I fully expect Woke incompetence to have played a part.
This incident should not have shut down the airport. There is redundancy in the supply arrangements, & Heathrow should have been able to weather the loss of a single intake substation without significant disruption.
I fully expect Woke incompetence to have played a part.
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