Classic 275,000 volt, 15,000Mva JW420 bulk oil breaker

Mark W · Sep 22, 2022

The above picture was taken at the festival of Britain and it shows a BTH bulk oil breaker, for me this represents the development of the super grid and how Britain was able to assist the world in developing higher transmission voltages.

These units are still in service and in only a few years time they will all be gone with no efforted being made to save at least one example. They have now all exceeded their design life by decades in most cases and have kept the lights on whilst the rest of the world continues with its progression. This breaker was developed in the very early 1950's and only a decade or so before, it was thought that 132kv was the maximum voltage to be used.

No one is trying to save this kit and in a few years time I think several organisations will want to turn the clock back to at least save some examples, walking into a science museum and being presented with this monster would be pretty impressive!!

My personal campaign is to do this, obtain the kit, hide it away and then release it all back into the public eye when people think it has all been scrapped and disposed off.

So, you need to find one first that is being removed in a careful fashion, the problem being that when something like this is being removed the pressure on the engineers to replace with new is massive, no time for sentimental thoughts.......flame torch, get it out!

Load it on to the back of a wagon,

Ensure it is strapped down.

Follow it down the motorway

Install the bushings.

Then have ago at the lad who helped me for not wearing any safety gear!!!

We now have one, to go with the other items I will slowly drip on to this forum.

I have since made contact with the daughter of one of the chief designers of this breaker and she is over the moon that one phase has now been saved for future generations.

Just by chance, one of the very few clips on youtube showing one of these in operation is this very breaker, no link to that film maker just pure luck!

I will start to add some details about how this works and how it could possibly be rated at 275Kv at 15,000Mva

UKMeterman · Sep 24, 2022

jay sean said:
Most National Grid sub stations are protected by electric fences, but Ive been to some where you still get visitors who want to and will steal copper!!!

I did hear of a case, I think it may have been in the USA, where someone stole parts of the earthing grid, then moved on to the control circuits, which triggered the fault thrower. The fault thrower then caused a voltage differernce across site bridged by thoses who stole the earth mat....