Early Electrics (or ‘a non-standard, experimental or unique historic electrification questions thread’)

[mike57]

Surely a quarter of the losses for the same conductor rail, (I^2xR).

Yes, but resistive losses in the feed conductors are not the only losses, although it does depend on where you start when looking at losses, overall based on experience in other industries I would say going from 630v to 1200v would reduce distribution losses on the DC side by a factor of ~3. Leakages will be higher at 1200v for example, but resistive losses will be the biggest factor, hence why France are considering 9kV DC for 1500v DC lines .

 

[Sun Chariot]

Id assume that’s because they might have had spare room, as I don’t believe those early electrics were third rail side contact

Yes, I used to wonder why the AL3 and AL4 culprits weren't stored at Longsight instead (as Piccadilly to Bury involves a shunt via Salford to access Victoria and then onto Bury line).

Bury steam shed certainly had the covered space; and so I suspect it was used as sufficiently out of the public eye, to avoid embarrassment. Shiny new AC locos not operable...

When I visited Bury steam shed - early 1991 - the recently-withdrawn fleet of 504 EMUs were easily accommodated within, and in front of, the old shed.

 

[AM9]

Yes, but resistive losses in the feed conductors are not the only losses, although it does depend on where you start when looking at losses, overall based on experience in other industries I would say going from 630v to 1200v would reduce distribution losses on the DC side by a factor of ~3. Leakages will be higher at 1200v for example, but resistive losses will be the biggest factor, hence why France are considering 9kV DC for 1500v DC lines .

I know that I said "same conductor rail", by which I meant was of the same cross sectional area. Of course the return through the running rail(s) and all connecting cables back to the substation is significant to the efficiency of the delivery of power. So the resistive loss for 1200V would be very slightly about 0.275 of that for 630V. Leakage power would depend on weather, ground dryness and state of insulation but I doubt it would be that much outside flood or snow conditions.

 

[GRALISTAIR]

Id assume that’s because they might have had spare room, as I don’t believe those early electrics were third rail side contact

Correct. That was my understanding at the time. They were merely being stored their as I don't think they had space at Crewe Electric Depot, Longsight, Willesden or Glasgow Shields Rd. Still, I was happy to see them (AC overhead locos) stored there. I did have a ride on those side contact electric multiple units from Manchester Victoria to Bury.

 

[AM9]

Correct. That was my understanding at the time. They were merely being stored their as I don't think they had space at Crewe Electric Depot, Longsight, Willesden or Glasgow Shields Rd. Still, I was happy to see them (AC overhead locos) stored there. I did have a ride on those side contact electric multiple units from Manchester Victoria to Bury.

I suppose they sounded and felt just like a 2-car 304 without the transformer hum/buzz and tap changing noises.

 

[hexagon789]

I suppose they sounded and felt just like a 2-car 304 without the transformer hum/buzz and tap changing noises.

Different traction motors though, would that not affect the sound?

The 504s had EE motors, the 304's were BTH.

 

[edwin_m]

Surely, like the normal overhead wire approach, the return current from the conduit is through the rails, so only a positive is needed.

That would appear to make sense, but apparently not so. https://www.tramwayinfo.com/Tramframe.htm?https://www.tramwayinfo.com/Models/Howto/Current.htm

In some systems, like London, the slot was between the rails, usually but not always in the centre of the track. On others the slot was incorporated into the groove of one of the running rails. In the tunnel there were two collector bars, one positive and one negative (the running rails were not used as the return).

There's a photo on this page (also some details of stud and other systems) but it's not very clear. There's a short section of conduit in the London Transport Museum (or was when I visited some years back) and it clearly shows two conductors.

 

[ThirteenArches]

Surely a quarter of the losses for the same conductor rail, (I^2xR).

Yes, I was being lazy - voltage drop was what I was referring to.

 

[GRALISTAIR]

I suppose they sounded and felt just like a 2-car 304 without the transformer hum/buzz and tap changing noises.

Different traction motors though, would that not affect the sound?

The 504s had EE motors, the 304's were BTH.

To be truthful, I don't remember. I cleared them all for sight though.

 

[Harpo]

Different traction motors though, would that not affect the sound?

The 504s had EE motors, the 304's were BTH.

Electric motors are silent. But not the transmission.

 

[Belperpete]

This became an outlier, with a frequency different to the public supply standard of 50Hz (60Hz in USA etc) because it required the railway to have its own power generators and distribution system, as indeed was the case in Germany, Switzerland, etc, with their 16.6Hz systems. Only in recent times have power electronics reached the state where they can convert frequencies straightforwardly, and by this time locomotive motors had moved on as well.

The LSWR DC system produced the DC using massive mercury-arc rectifiers in large glass bulbs (think of a massive flash bulb, about 5 ft or so tall from memory - each one must have contained gallons and gallons of mercury). I can remember seeing some of these in service - the light show when you took the covers off was quite spectacular.

As well as the transformers and rectifiers, the sub-stations also contained rotary converters, as the track-circuits required a 75 Hz supply. 75 Hz AC was used to make the track-circuits immune to the DC traction, and also to the 50 Hz harmonics in the DC. The track-circuits also used phase-sensitive vane relays, to make them immune to both DC and any stray AC voltages. They were later converted to 50 Hz operation, and the rotary converters abolished, when it was found that the vane relays were sufficiently immune to the 50 Hz harmonics in the traction. However, when the mercury arc rectifiers were later replaced by solid-state rectifiers, the DC traction they produced contained far higher harmonic levels which caused interference issues with some S&T equipment.

The old rotary converter station at Clapham Jcn was like a small, brick cathedral, and was repurposed as the S&T training school.

 

[Elecman]

1200dc was possibly chosen for Manchester=- Bury because it allowed a single feeder to be used, from the dedicated power station at Clifton Junction. Twice the voltage, half the current, half the resistive losses for the same cross- section. The wires went over the Clifton viaduct (MY Thirteen Arches) on gantries, which made me do a double- take when I saw the Aerofilms aerial photos of the area. I ran to the history books to find out when the Clifton to Radcliffe line was overhead electric - it never was.

The 3rd rail traction substation was actually located at Manchester Victoria in the arches off Aspin Lane

 

[contrex]

I believe that quote actually referred to the "conventional" wire system with no conduit, and the question was about touching the running rail. On the conduit system there is no wire (except at changeover points) and the conduit contains both positive and negative rails.

Yes, abolutely! I was actually on a jolly to Cardiff today, in 802 011, and had just left Severn Tunnel Junction, when that occurred to me. The word 'plough' popped into my head. The old lady was looking at a running rail. I don't use this site on my phone; I find it unusable.

== Doublepost prevention - post automatically merged: 12 Mar 2025 ==

The LSWR DC system produced the DC using massive mercury-arc rectifiers in large glass bulbs (think of a massive flash bulb, about 5 ft or so tall from memory - each one must have contained gallons and gallons of mercury). I can remember seeing some of these in service - the light show when you took the covers off was quite spectacular.

I was under the impression that the LSWR 1915 scheme used DC traction current provided by rotary converters fed at 11 kV 3-phase from Durnsford Road. The one at Barnes gets quite a mention in the Accident Report on the collision at Barnes Bridge in 1954.

 

[billio]

The 3rd rail traction substation was actually located at Manchester Victoria in the arches off Aspin Lane

1200dc was possibly chosen for Manchester=- Bury because it allowed a single feeder to be used, from the dedicated power station at Clifton Junction. Twice the voltage, half the current, half the resistive losses for the same cross- section. The wires went over the Clifton viaduct (MY Thirteen Arches) on gantries, which made me do a double- take when I saw the Aerofilms aerial photos of the area. I ran to the history books to find out when the Clifton to Radcliffe line was overhead electric - it never was.

And here is a picture of the overhead gantries on the viaduct. Why did they need so many wires? These continued on wooden pylons alongside the railway to the substation at Radcliffe. Not sure hw they were taken over the Irwell viaduct at Radcliffe.

 

[Springs Branch]

North of Liverpool is flat and has a mild coastal climate.

North of Manchester is hilly and has (had) a harsh Pennine climate.

Might the Bury system have been chosen on account of its greater oomph, as well as its ice-resistance?

I don’t think the L&Y were at any time considering main line electrification, but there were definitely plans to extend the 1200v Bury system onto the Oldham loop and possibly further.

I wonder if the original plan to also electrify the Oldham Loop was a factor in choosing the side-contact conductor rail (irrespective of the choice of voltage)? Certainly that route goes a bit higher towards the Pennines and more prone to ice and snow disruption than any of the other third rail systems being implemented in the early 20th century.

1200dc was possibly chosen for Manchester=- Bury because it allowed a single feeder to be used, from the dedicated power station at Clifton Junction. Twice the voltage, half the current, half the resistive losses for the same cross- section. The wires went over the Clifton viaduct (MY Thirteen Arches) on gantries, which made me do a double- take when I saw the Aerofilms aerial photos of the area. I ran to the history books to find out when the Clifton to Radcliffe line was overhead electric - it never was.

According to a couple of sources*, there were originally two substations - one at Manchester Victoria and another at Radcliffe. The feeder for the Radcliffe substation ran from the Clifton power station alongside the ex-East Lancashire Railway line from Clifton Junction to Radcliffe & Bury (obviously just using the railway alignment - that line was never electrified).

Between around 1918 and 1952, the side-contact third rail also extended northwards beyond Bury Bolton St. to Holcombe Brook. The Holcombe Brook branch was only around 4 miles long and mostly operated short trains but probably benefited from an extra bit of juice from having a substation at Radcliffe.

I'm not sure whether or not the Radcliffe substation was closed later on. Possibly a result of the Holcombe line shutting, the downturn in Manchester - Bury services from the 1960s and after the convenient right-of-way between Clifton Jn and Radcliffe Central was closed post-Beeching.

There's also a story - presumably from the late 1980s, just before conversion to Metrolink - that one day, during some digging operations in Salford associated with construction of the Windsor Link or Salford Crescent station, there was a flash, a bang and the lights went out and all the trains coasted to a halt far away on the Bury line. Although the L&Y's Clifton power station was long gone, the Bury line's connection to the grid was still made in the Clifton area and used the original buried cable from there to Victoria - and its presence had been forgotten by the modern-day BR engineers.

* For example, Electric Railways of Liverpool and Manchester by Graeme Gleaves.

 

[billio]

This photograph shows the transition from the overhead gantries to the wooden pylons alongside the tracks. The telegraph wires are on the left.

 

[AM9]

This photograph shows the transition from the overhead gantries to the wooden pylons alongside the tracks. The telegraph wires are on the left.

The six wires on the right side of the gantries look like the three phase feeds that the east coast lines in the US have, using railway lands as there would have been no national grid infrastructure then.

 

[Springs Branch]

I’ve heard of it being compared aesthetically to the NYC subway but did it have a frequency vaguely like a subway?

Having used NYC subway between Manhattan Midtown and Jamaica Centre (past Queens), I think the Manchester Bury line and stock were far superior!

Anyone who has ridden on both a Bury Line 504 and the NY Subway within living memory would emphatically agree with @Sun Chariot that there's no comparison!

But it might depend on when that comparison was originally made.

If we're talking about the L&Y's initial electric stock from 1916 versus early NYC subway cars from about the same era - there may have been more similarities. The Subway stock back then was still quite utilitarian but more lightweight and a lot less metallic and "bomb proof" than the trains introduced from the mid-20th Century onwards.

For example, the IRT Composite cars of 1904 vintage:

File:NYCS IRT composite drawing.jpg - Wikimedia Commons

commons.wikimedia.org

File:IRT Composite Interior.jpg - Wikimedia Commons

commons.wikimedia.org

Compared to the look of the 1916 Manchester - Bury stock - seen part way down this page of The Lancashire & Yorkshire Railway Society's website.

 

[mike57]

The LSWR DC system produced the DC using massive mercury-arc rectifiers in large glass bulbs

The initial scheme used rotary converters as at this point in time (1913-1917) mercury arc rectification was still being developed. The first mercury arc rectifiers started to appear in the early 1920s, and I think, but cannot confirm that the first UK application for rail traction was the City and South London railway.

 

[generalnerd]

Anyone who has ridden on both a Bury Line 504 and the NY Subway within living memory would emphatically agree with @Sun Chariot that there's no comparison!

But it might depend on when that comparison was originally made.

If we're talking about the L&Y's initial electric stock from 1916 versus early NYC subway cars from about the same era - there may have been more similarities. The Subway stock back then was still quite utilitarian but more lightweight and a lot less metallic and "bomb proof" than the trains introduced from the mid-20th Century onwards.

For example, the IRT Composite cars of 1904 vintage:

File:NYCS IRT composite drawing.jpg - Wikimedia Commons

commons.wikimedia.org

File:IRT Composite Interior.jpg - Wikimedia Commons

commons.wikimedia.org

Compared to the look of the 1916 Manchester - Bury stock - seen part way down this page of The Lancashire & Yorkshire Railway Society's website.

Ah I see. I was more thinking from a ‘run down’ point of view but looking at some subway stations even now it looked far superior.

 

[Harpo]

Anyone who rode on a 302/4/5/8 will have experienced a very similar ride to a 504. Those who rode on 302 244 may well have travelled in its ex-504 driving trailer.

 

[contrex]

The initial scheme used rotary converters as at this point in time (1913-1917) mercury arc rectification was still being developed. The first mercury arc rectifiers started to appear in the early 1920s, and I think, but cannot confirm that the first UK application for rail traction was the City and South London railway.

If it was, it must surely have been in 1915, when the C&SLR DC-generating power station at Stockwell was closed, and AC supply taken from Lots Road. The former five-wire 'Highfield' DC system was interesting, and a blog by 'machorne' gives some detail:

Obtaining power from the new substations [Stockwell, Elephant & Castle, & Old Street] allowed the efficient but idiosyncratic distribution system to be standardized too. Hitherto the running rails had been at zero volts with the current rails on the northbound line at +500 volts and those on the southbound line at -500 volts. These were supported by feeders at +1000 and -1000 volts respectively (a potential difference of 2000 volts). At the substations were rotating machines called balancers, together with batteries, which sought to maintain consistent traction voltage notwithstanding the lengthy distance from the power house. Section gaps had to be left in the current rails approaching termini so that the traction polarity could be reversed without the risk of a disastrous short circuit. While this ‘Highfield’ 5-wire system wasn’t a model of efficiency it worked well enough until a reliable alternating current high-voltage distribution system came along.

1915 – Events on the London Underground a Century Ago

During 1913 I thought it might be worthwhile to note significant historical events that occurred in years gone by on a month by month basis. A triumph of hope over experience, this proved hopelessl…

machorne.wordpress.com

 

[mike57]

If it was, it must surely have been in 1915, when the C&SLR DC-generating power station at Stockwell was closed, and AC supply taken from Lots Road. The former five-wire 'Highfield' DC system was interesting, and a blog by 'machorne' gives some detail:

I think they were still using rotary converters in 1915. I was told a lot years ago from someone who may have been around shortly after WW1:

"The Yerkes tubes used rotary converters - basically big AC motors that drive DC generator sets. Hence 11KVAC goes in (via big cables from the power station [Lots road]), and each substation produces line voltage."

Also found this, which backs up my theory that it was post 1920 before mecury arcs appeaed: https://digital-library.theiet.org/doi/abs/10.1049/esej:19950411?download=true

 

[contrex]

I think they were still using rotary converters in 1915. I was told a lot years ago from someone who may have been around shortly after WW1:

"The Yerkes tubes used rotary converters - basically big AC motors that drive DC generator sets. Hence 11KVAC goes in (via big cables from the power station [Lots road]), and each substation produces line voltage."

Also found this, which backs up my theory that it was post 1920 before mecury arcs appeaed: https://digital-library.theiet.org/doi/abs/10.1049/esej:19950411?download=true

I am now inclined to think it may have been Balham in 1926, which was again the first LT substation in 1964 to use silicon semiconductor rectifiers.

 

[mike57]

I am now inclined to think it may have been Balham in 1926, which was again the first LT substation in 1964 to use silicon semiconductor rectifiers.

Yes I have heard Balham mentioned more than once, which is a bit of a coincidence as I was born in Balham in the 50s. There are some old pictures floating around of the bit behind Chesnut Grove in the 50s, I will see that sheds any light, as I am sure it was underground related.

The SR placed a large order for Mercury Vapour rectifiers in 1927 which were used for the electrification southwards.

Once the technology was perfected they became the norm for all new stuff. They are pretty robust when used in a fixed installation (unlike the early electrics) and will cope with overloads. Volt drop is 20-30v so efficency is OK, 3-5% losses (25v v 600v).

 

[AM9]

Volt drop is 20-30v so efficency is OK, 3-5% losses (25v v 600v).

That's peanuts compared to the rest of the losses of LVDC electrification.

 

[contrex]

Yes I have heard Balham mentioned more than once, which is a bit of a coincidence as I was born in Balham in the 50s.

I was born in Camberwell in 1952, and my maternal grandmother lived in Oakmead Road, Balham, until she died in 1958.

== Doublepost prevention - post automatically merged: 13 Mar 2025 ==

I think they were still using rotary converters in 1915. I was told a lot years ago from someone who may have been around shortly after WW1:

"The Yerkes tubes used rotary converters - basically big AC motors that drive DC generator sets. Hence 11KVAC goes in (via big cables from the power station [Lots road]), and each substation produces line voltage."

Also found this, which backs up my theory that it was post 1920 before mecury arcs appeaed: https://digital-library.theiet.org/doi/abs/10.1049/esej:19950411?download=true

A true rotary converter (as distinct from a motor-generator set) has one winding, an 'AC side' with slip rings, and a 'DC side' with a commutator. An interesting feature is that they can work either way around, so you could feed DC to the commutator side, the machine would run up, and you could then collect 3-phase AC from the slip rings. In fact there is a YouTube video showing a preserved New York Subway (IRT) rotary being run up from the third rail. I love these beasts.

 

[trebor79]

Electric motors are silent. But not the transmission.

They aren't. AC motors on particular make distinctive noises due to electromagnetic induced vibration.

The old rotary converter station at Clapham Jcn was like a small, brick cathedral, and was repurposed as the S&T training school.

Does it still exist?

 

[Bevan Price]

Volume 2 of John Marshall's History of the L&YR contains a chapter on the electrification. Many of the details agree with those in post #10 above.
Some extra details:
Southport line - a power station at Formby struggled to keep up with power demands at peak hours, so booster battery stations were provided at several locations.
Before the start of regular electric services, a special electric train ran from Liverpool to Southport in 14 minutes - an average of 70 mph, and probably unequalled since then. The initial electric service from Liverpool was 119 trains per day as far as Hall Road, of which 65 continued to Southport (schedule 37 minutes). 17 trains continued from Southport to Crossens; these ran express between Liverpool & Southport, with schedule 25 minutes.

Bury line - the side contact 3rd rail was a requirement for safety of linside workers. Apart from lower voltage drops, no reason if specified for the choice of 1200 V.

L&YR proposed to electrify between Manchester, Oldham, Shaw & Royton, but (housing) developments near the line did not proceed as expected, and the proposal was dropped after 1920.

 

[Taunton]

That would appear to make sense, but apparently not so. https://www.tramwayinfo.com/Tramframe.htm?https://www.tramwayinfo.com/Models/Howto/Current.htm

There's a photo on this page (also some details of stud and other systems) but it's not very clear. There's a short section of conduit in the London Transport Museum (or was when I visited some years back) and it clearly shows two conductors.

I wonder if this was done because of fear of electrolysis of the conduit equipment from return currents to earth through the adjacent running rails.

Must have added to the complexity of the equipment on the car, in particular ensuring that if the wheels were electrically isolated in conduit operation it was assured that the return via conduit was complete, otherwise not only would the car not work (starting with the lights going out) but boarding passengers might receive an electric shock when they touched the handrail while still stood on the ground. This was not unknown in depots if the car came to a stand on spilled sand.