What is (was?) this electrical building for?

[EM2]

Way back in the mists of time, I started my career as a trainee S&T technician, based at Chislehurst Junction signal box.
Just opposite the box was a large brick structure, which I know was connected somehow with the electrical system, bit I have forgotten exactly how. We even visited it once, but what the machinery within was for, I have completely forgotten!
On this Google Maps screen, the signal box was on the large grey patch on the left, the structure I'm interested in is the centre, between the two main lines.
https://goo.gl/maps/Amob6ECdxk32

 

[Elecman]

Looks like a DC Traction substation to me

 

[yorksrob]

Yes, one of the early, quite impressive ones. They've got smaller over the years.

 

[John Webb]

Is it the building just visible on the left of this elderly photo? (Click on photo to go to the larger original.)
Victoria - Kent Coast express near Bickley Junction, 1950

© Copyright Ben Brooksbank and licensed for reuse under this Creative Commons Licence.
If so, then yes, it's an electric substation where the incoming AC voltage from the grid, at probably 11kV or 33kV, was transformed down and rectified to provide the DC traction current for the third rail. The conversion was done originally by rotary converters - a motor/generator set - or by mercury arc rectifiers; these were both bulky and need a lot of space. Modern 'solid-state' rectifiers take up much less space so the substations are much smaller.

 

[EM2]

Ah, yes! That sounds very familiar.
Thanks all.

 

[contrex]

I believe these substations were nicknamed "cathedrals" in Southern Railway days, and needed to have an overhead crane to move the rotaries into and out of their positions.

 

[bramling]

I believe these substations were nicknamed "cathedrals" in Southern Railway days, and needed to have an overhead crane to move the rotaries into and out of their positions.

Indeed, the SECR design is particularly attractive, all three of the Southern constituents having their own design. All surviving examples were re-equipped in the 1950s from when onwards they were massively oversized, at the same time the electrification was completely redesigned such that not all were required in the new setup.

Similar ones survive in use at Victoria, Loughborough Junction, Nunhead, Shortlands, Cannon Street, Lewisham, Grove Park, Albany Park, Charlton, Plumstead, Belvedere and Dartford. The remainder have been lost over the years.

 

[theageofthetra]

I believe these substations were nicknamed "cathedrals" in Southern Railway days, and needed to have an overhead crane to move the rotaries into and out of their positions.

That's interesting about the cranes. I always assumed they were so big due to the heat generated by the early equipment but having a traverser crane would explain it. Are there any pictures about of the interiors of them.?

 

[yorksrob]

I believe there used to be one at Eltham Park at one stage.

 

[bramling]

I believe there used to be one at Eltham Park at one stage.

Yes this one simply vanished at some point, having been redundant since the 1950s (replaced by new substations either side at Eltham Well Hall and Bexleyheath). Three others have also gone - Upper Sydenham which presumably also became redundant in the 1950s, Elmers End which for some reason was replaced with a new substation immediately adjacent in the 1950s and survived empty until about the 1990s IIRC; and Barnehurst which became a (ridiculously over-sized!) TP Hut in the 1950s, and survived as such until very recently when it was demolished to make way for being converted back to a substation as part of the 12-car works.

How anyone can have the heart to demolish such an attractive building I’ll never know!

 

[yorksrob]

Yes this one simply vanished at some point, having been redundant since the 1950s (replaced by new substations either side at Eltham Well Hall and Bexleyheath). Three others have also gone - Upper Sydenham which presumably also became redundant in the 1950s, Elmers End which for some reason was replaced with a new substation immediately adjacent in the 1950s and survived empty until about the 1990s IIRC; and Barnehurst which became a (ridiculously over-sized!) TP Hut in the 1950s, and survived as such until very recently when it was demolished to make way for being converted back to a substation as part of the 12-car works.

How anyone can have the heart to demolish such an attractive building I’ll never know!

Indeed. What a pity they didn't reuse the Barnhurst one .

 

[swt_passenger]

I’m thinking that Raynes Park, can be seen located in the branch ‘triangle’, was repurposed as one of the Wessex electrification control rooms, (ECRs)?

 

[bramling]

I’m thinking that Raynes Park, can be seen located in the branch ‘triangle’, was repurposed as one of the Wessex electrification control rooms, (ECRs)?

Not quite. The ECR was purpose built (again as part of the 1950s scheme IIRC) and sits alongside the old substation. That substation was another which fell out of use for its original purpose although I believe it then became another extra-large TP hut. I’m not sure whether it’s since been upgraded back to a substation as part of the power supply upgrades. Plenty of cathedral substations still survive on the south western and south central divisions too, and a few on Merseyrail and on the North London lines for that matter. Not to mention plenty on London Underground, mostly still in use.

 

[HaggisBotherer]

The Southern Railway concrete version is a style I've always been oddly fond of
https://www.geograph.org.uk/photo/4497815

 

[contrex]

the SECR design is particularly attractive, all three of the Southern constituents having their own design.

As I understood it, only the LSWR and the LBSCR had any electrification before the Grouping in 1922 that formed the Southern Railway, and of those, only the LSWR used third rail DC. All of the pre-BR era electrification in the former SECR area was done by the Southern Railway from about 1925 on, using the LSWR system. Designs varied from one SR scheme to another, and some R/C stations were re-used for mercury arc equipment, I think.

There is an excellent RMWeb page giving details - http://www.rmweb.co.uk/community/index.php?/topic/103304-substations-and-tp-huts/

 

[John Webb]

I believe these substations were nicknamed "cathedrals" in Southern Railway days, and needed to have an overhead crane to move the rotaries into and out of their positions.

The Mercury Arc rectifiers weren't lightweight either - and being a large quantity of mercury in a large glass vessel, needed considerable care when being moved, I have been told.

 

[yorksrob]

As I understood it, only the LSWR and the LBSCR had any electrification before the Grouping in 1922 that formed the Southern railway, and of those, only the LSWR used third rail DC. All of the pre-BR era electrification in the former SECR area was done by the Southern Railway from about 1925 on, using the LSWR system. Designs varied from one SR scheme to another, and some R/C stations were re-used for mercury arc equipment, I think.

There is an excellent RMWeb page giving details - http://www.rmweb.co.uk/community/index.php?/topic/103304-substations-and-tp-huts/

That's an interesting page. It's amusing that we've gone from cathedrals to small factory type buildings, to bungalows, to shipping containers. Minaturisation writ large !

 

[contrex]

Glass bulb mercury arc rectifiers were only practical up to about 500 amps each. A substation of 2500 kW capacity would need two banks in parallel, each of six or eight bulbs, whereas from about 1925, by using steel tank type mercury arc rectifiers, only one or two could support the load. In 1927, the Southern bought 23 of these, 2500 kW capacity, from Bruce Peebles & Co for schemes in the Eastbourne, Hastings and Sevenoaks areas. That same company was the main subcontractor for the 1950s Woodhead scheme.

Arc type rectifiers co-existed alongside older rotary equipment, for decades until it was life expired, when the 1955 Barnes Bridge accident happened, a substation operator knew that something had happened when his rotary set began to run down. The 1950s "50 cycle scheme" was the conversion of the SR AC distribution system from 25 cycles (Hz) to 50 once the old rotaries were retired. The rotaries needed the lower frequency (like the trains in Germany, Austria, Sweden, etc on 16 2/3 Hz)

 

[t_star2001uk]

I can remember the one that used to be beside South Side training school at Waterloo. When we did short circuit bar training we went in to watch the high speed circuit breaker tripping. Interesting stuff..

 

[bramling]

That's an interesting page. It's amusing that we've gone from cathedrals to small factory type buildings, to bungalows, to shipping containers. Minaturisation writ large !

What mildly amuses me is the fact that one of the so-called benefits of the modern containerised types is supposed to be that they're quick and easy to install. Yet this never quite seems to be the case in practice - there still ends up being a massive site compound with works ongoing for months and months!

 

[yorksrob]

What mildly amuses me is the fact that one of the so-called benefits of the modern containerised types is supposed to be that they're quick and easy to install. Yet this never quite seems to be the case in practice - there still ends up being a massive site compound with works ongoing for months and months!

Indeed. For that amount of time they might as well build it out of brick. At least it will fit in with the countryside better.

 

[bramling]

Indeed. For that amount of time they might as well build it out of brick. At least it will fit in with the countryside better.

The older ones certainly do seem to hold up well, it’s one of those parts of the railway which often provides a link to the past.

I must admit to being a bit of a sucker for substations - even the 1950s and 1960s brick bungalow types (eg London suburban and Kent Coast electrification) to me exhibit a certain sinister charm. Then there’s the couple of London Underground ones built in redundant lift shafts which are also rather impressive along with all the associated cable tunnels. And anyone whose ever visited an ECR can’t fail to be impressed by the calm laid-back professionalism of these specialist staff.

 

[theageofthetra]

Glass bulb mercury arc rectifiers were only practical up to about 500 amps each. A substation of 2500 kW capacity would need two banks in parallel, each of six or eight bulbs, whereas from about 1925, by using steel tank type mercury arc rectifiers, only one or two could support the load. In 1927, the Southern bought 23 of these, 2500 kW capacity, from Bruce Peebles & Co for schemes in the Eastbourne, Hastings and Sevenoaks areas. That same company was the main subcontractor for the 1950s Woodhead scheme.

Arc type rectifiers co-existed alongside older rotary equipment, for decades until it was life expired, when the 1955 Barnes Bridge accident happened, a substation operator knew that something had happened when his rotary set began to run down. The 1950s "50 cycle scheme" was the conversion of the SR AC distribution system from 25 cycles (Hz) to 50 once the old rotaries were retired. The rotaries needed the lower frequency (like the trains in Germany, Austria, Sweden, etc on 16 2/3 Hz)

Fascinating. Thanks