THE ELECTRIFICATION OF MADRID-AVILA-SEGOVIA LINE
The electrification Madrid-Avila-Segovia (MAS) was the first one acomplished by Renfe, although its project was done in 1928, encharged by the North Company. This was a line with strong ramps, wich was very normal by that time in electrifications. This fact supposed to substitute the steam traction only on the trajects where bigger power was needed. This point of view would gradually change in Renfe's different plans of electrification.
The project of electrification was rewiewed in 1934 and the works didn't start until 1935, but they were suddenly interrupted by the beggining of the Civil War. Renfe took the project of the North Company and it finished with the electrification of the M.A.S, with a system of continuous power of 1.500 v in 1994. Its official inaguration was on the 9 th February of 1946.
To the electrification of the M.A.S. (Madrid-Avila-Segovia line), the energy was supplied to the substations with alternating power of 46.000 volts in Madrid, Otero and Avila. The suppliers were: Hidroeléctrica Española, Iberduero and Unión Eléctrica Madrileña.
The line had a total of eleven substations, wich received the energy on alterning current and transformed it into continous current at 1.500 v, in 1994. This transformation was done by means of switches of 750 kw of power, joint toghether in groups of two in order to form transformation groups of 1.500 kw, with a tension of 1.500 v, wich is the supply of the contac line.
One of the most important station of this line was Las Matas, wich was officialy inagurated by the head of the Spanish Government by those years, Francisco Franco.
The electrification meant a big effort for Renfe and for the country in general. As there was not enough copper available to manufacture the neccesary contact wire, it became neccesary to melt some coins made of that metal to solve the problem of the raw material.
The line Madrid-Avila-Segovia is supplied by a transport line in high tension wich is known as line Y.
On the 11th April of 1972, the tension of the M.A.S. was changed from 1.500 v to 3.000 v. Although the tension of 1.500 v gave excellent results, the transformation was recomended for some important reasons: increase the power, increase the electric tension , modernizing the system of electrification, comand the stations and renewing the catenary.
In this sense, the group of rectification of mercury steam installed in 1966 in Avila substation, was replaced by a rectification of silicon in order to be applied to different groups; the eleven substations of the line were remote controlled from a unique post installed in Villalba.
The chosen material for the traction on this line was formed by locomotives serie 7.400 and 7.500 and train units of the serie 300.
Before receiving the locomotives serie 7.400, the line was served by machines serie 7.000 and 7.800 comming from the electrifications of Catalonia. Locomotives serie 7.400 were on service between 1944 and 1950. They were buildt by Devis (Macosa) and Sechreroh, and they were the first electric locomotives required by Renfe. The were used to tow freight trains in the line Madrid-Avila-Segovia. They had their base in the deposits of Príncipe Pío station.
Between 1944 and 1954 some locomotives of that serie went to Torre del Bierzo, where they would tow trains in the electrificated rump of Torre Brañuelas, wich was temporally on service at 1.500 v. until 1949, when it was transformed to 3.000 v. when the electrification of Torre to Ponferrada was inagurated.
As there was a change of tension on the M.A.S line in 1972, locomotives of the serie 7.400 were transfered to the Vasc Country, where electrifications at 1.500 v. were still kept. In 1978 they definitely stoped running for Renfe.
Locomotives serie 7.500 were the most powerful ones, from Renfe until the arrival of the japaneese ones, serir 279, in 1967. This locomotive was asigned to the line Madrid-Avila-Segovia in order to tow passenger trains. The serie was formed by twelve locomotives, with a total weigh of 147 tons and a continuous power of 2.580 Kw. They were buildt by CAF, Brown Bovery Oerlikon, between 1944 and 1945.
This locomotives belong to the type 2 CoCo 2 (two free axis in each extreme and six axis in engines). The engine axis and bogies are held in two big wheelbarrows, over them it laid the box of the locomotive.
The bogies are used to take the bends easily ant to improve its stability for high speeds.
The locomotives also have six traction engines and each one propels an axis. Locomotives serie 7.500 were transported in 1972 to the Vasc Country and they stoped running for Renfe in July 1972.
The electric units of the serie 300 were the first vehicles of this kind (normal gauge) circulating in Spain. The units of this train are specially designed to the passenger traffic, mainly suburban lines. They appeared in Spain at the same time than the first electrifications made on lines of the north of Spain by 1930. The units numbers 349 to 378 were received by Renfe between 1943 and 1945 in order to give service in the line Madrid-Avila-Segovia.
The mechanic side of those units was made by Naval and the elcectric equipement by the American companies Metropolitan Vickers and Westinghouse. The Spanish companies Cenemensa and Experiencias Industriales de Aranjuez cooperate as well in the construction.
Is composition is formed by two cars: engine and towing. The inside distribution has two departments for passengers and one central platform with some doors. Apart from these doors, there are another small doors in both sides of the car.
The engine car has a van and sixty seven sits. The towing car has one hundred and four sits.
Inmaculada García Lozano
Railway Historian
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