Article: In the UK, the London, Brighton and South Coast Railway pioneered overhead electrification of its suburban lines in London, London Bridge to Victoria being opened to traffic on 1 December 1909. Victoria to Crystal Palace via Balham and West Norwood opened in May 1911. Peckham Rye to West Norwood opened in June 1912. Further extensions were not made owing to the First World War. Two lines opened in 1925 under the Southern Railway serving Coulsdon North and Sutton railway station. The lines were electrified at 6.7 kV 25 Hz. It was announced in 1926 that all lines were to be converted to DC third rail and the last overhead electric service ran in September 1929.

Now answer this question: What voltage was used in the two lines opened in 1925 of Southern Railway?
6.7 kV 25 Hz
Artikel: I Storbritannien var London, Brighton och South Coast Railway pionjärer när det gällde att elektrifiera sina förortslinjer i London, London Bridge till Victoria som öppnades för trafik den 1 december 1909. Victoria till Crystal Palace via Balham och West Norwood öppnade i maj 1911. Peckham Rye till West Norwood öppnade i juni 1912. Ytterligare utvidgningar gjordes inte på grund av första världskriget. Två linjer öppnade 1925 under Southern Railway som betjänade Coulsdon North och Suttons järnvägsstation. Linjerna elektrifierades vid 6,7 kV 25 Hz. Det meddelades 1926 att alla linjer skulle byggas om till DC tredje järnväg och den sista överliggande eldriften kördes i september 1929. Svara nu på denna fråga: Vilken spänning användes i de två linjer som öppnades 1925 av Södra järnvägen?
Article: In the United Kingdom, the London, Brighton and South Coast Railway were pioneers in electrifying their suburban lines in London, London Bridge to Victoria opened to traffic on 1 December 1909. Victoria to Crystal Palace via Balham and West Norwood opened in May 1911. Peckham Rye to West Norwood opened in June 1912. Further enlargements were not made due to World War I. Two lines opened in 1925 under the Southern Railway serving Coulsdon North and Sutton railway station. The lines were electrified at 6.7 kV 25 Hz. It was announced in 1926 that all lines would be converted to DC third railway and the last overhead electric drive was run in September 1929. Now answer this question: What tension was used in the two lines opened in 1925 by the Southern Railway?
6,7 kV 25 Hz
6,7 kV 25 Hz