Tim Humphreys ex Mudhen
Western Thunderer
Another day spent spent in front of the log stove checking records.; primarily from Trains Illustrated and Modern Railways with a little conjecture. Great fun going through them and finding all kinds of interesting articles. i don't know how i ever had time to go to work
Firstly the issue of dual voltage on the LMR electrification, did they or didn't they?
In 1956 BTC announced the decision to electrify the Euston to Manchester/Liverpool route at 25k ac rather 1500 dc. There was a caveat added stating that more tunnels and bridges would need to be modified for ac than dc. As a result where this was not practicable, for example long tunnels and through built-up areas, the line voltage would be reduced to 6.25kv where reduced clearances would be satisfactory. Confirmation of this choice was reinforced by the announcing of the placing of contracts for the first locomotives which stated that they would operate on 25kv/6.25kv. The first batches of locos were delivered in 1960 with this configuration.
Later in the year on announcing that stage 1 was completed between Crewe and Manchester the use of 25kv only is mentioned, nothing on 6.25kv. Great detail is given to the amount of work undertaken to increase clearances which would lead me to suggest that no 6.25kv sections were included.
In August 1963 Modern Raiways reports: After lengthy discussion with the Ministry of Transport and equally lengthy experiments on the actual equipment the MOT has given dispensation for a reduction in electrical clearance from 11in to 8in under special conditions.In addition itwas found that if the LMR were to adopt the standard 13ft 1in load gauge in place of the previous 13ft 6in ( a legacy of the LNWR) it would be possible to operate the Euston-Manchester-Liverpool scheme throughout on 25kv and completely eliminte the complication and expense of voltage changeover equipment.
After much digging through my references I can't determine whether any stretches of 6.25kv were constructed on the whole route through to Euston. This could well have happened in some areas in the north west where the EMUs built for service in this area were equipped to run on the two voltages.
Great Eastern electrification - extent of 6.25kv operation.
After conversion from 1500dc the 6.25kv system ran from Liverpool Street to Shenfield and then on to Southend. The line between Shenfield and Chelmsford has always been 25kv.
To the North east of London the 6.25kv extended to a point just south of Cheshunt station.
At later dates, not discovered so far but probably coinciding with the introduction of electric locomotives on the GE I believe, all lines were converted to 25kv. The GE had huge problems on the NE London section with dual voltage; there is detailed description in the August 1961 Trains Illustrated. The problems were solved by modify the trains and not by changing voltage to 25kv.
The Colchester to Clacton and Walton section was officially opened on the 13th April 1959 as a test bed for 25kv electrification although it had been operating since 16th March. Many if not all EMU sets were tested in public service, on this line including the LTSR stock.
There is much evidence that all EMUs built for the Great Eastern right through to the introduction of the Clacton units were designed to operate on two voltages. This was achieved as follows, to quote, Current is fed from the pantograph through an air blast circuit breaker to the voltage changeover switch, which connects to the four sections of the transformer primary in series for 25kv and in parallel for 6.25kv operation.
Thats all for now folks
Tim
Firstly the issue of dual voltage on the LMR electrification, did they or didn't they?
In 1956 BTC announced the decision to electrify the Euston to Manchester/Liverpool route at 25k ac rather 1500 dc. There was a caveat added stating that more tunnels and bridges would need to be modified for ac than dc. As a result where this was not practicable, for example long tunnels and through built-up areas, the line voltage would be reduced to 6.25kv where reduced clearances would be satisfactory. Confirmation of this choice was reinforced by the announcing of the placing of contracts for the first locomotives which stated that they would operate on 25kv/6.25kv. The first batches of locos were delivered in 1960 with this configuration.
Later in the year on announcing that stage 1 was completed between Crewe and Manchester the use of 25kv only is mentioned, nothing on 6.25kv. Great detail is given to the amount of work undertaken to increase clearances which would lead me to suggest that no 6.25kv sections were included.
In August 1963 Modern Raiways reports: After lengthy discussion with the Ministry of Transport and equally lengthy experiments on the actual equipment the MOT has given dispensation for a reduction in electrical clearance from 11in to 8in under special conditions.In addition itwas found that if the LMR were to adopt the standard 13ft 1in load gauge in place of the previous 13ft 6in ( a legacy of the LNWR) it would be possible to operate the Euston-Manchester-Liverpool scheme throughout on 25kv and completely eliminte the complication and expense of voltage changeover equipment.
After much digging through my references I can't determine whether any stretches of 6.25kv were constructed on the whole route through to Euston. This could well have happened in some areas in the north west where the EMUs built for service in this area were equipped to run on the two voltages.
Great Eastern electrification - extent of 6.25kv operation.
After conversion from 1500dc the 6.25kv system ran from Liverpool Street to Shenfield and then on to Southend. The line between Shenfield and Chelmsford has always been 25kv.
To the North east of London the 6.25kv extended to a point just south of Cheshunt station.
At later dates, not discovered so far but probably coinciding with the introduction of electric locomotives on the GE I believe, all lines were converted to 25kv. The GE had huge problems on the NE London section with dual voltage; there is detailed description in the August 1961 Trains Illustrated. The problems were solved by modify the trains and not by changing voltage to 25kv.
The Colchester to Clacton and Walton section was officially opened on the 13th April 1959 as a test bed for 25kv electrification although it had been operating since 16th March. Many if not all EMU sets were tested in public service, on this line including the LTSR stock.
There is much evidence that all EMUs built for the Great Eastern right through to the introduction of the Clacton units were designed to operate on two voltages. This was achieved as follows, to quote, Current is fed from the pantograph through an air blast circuit breaker to the voltage changeover switch, which connects to the four sections of the transformer primary in series for 25kv and in parallel for 6.25kv operation.
Thats all for now folks
Tim
. Perhaps we should just have a thread on rail electrification in general.
