▁locomot ives ▁power ed ▁by ▁ 5 0   Hz ▁altern ating ▁current . ▁It ▁arranged ▁the ▁supply ▁contract s ▁for ▁the ▁W AM - 1 , ▁W AG - 1 ▁and ▁W AG - 3 ▁locomot ives ▁and ▁its ▁spare ▁parts . ▁ ▁The ▁first ▁section ▁elect r ified ▁with ▁the ▁ 2 5 ▁k V ▁AC ▁system ▁was ▁Raj ▁Kh ars wan – D ongo ap osi , ▁on ▁the ▁South ▁Eastern ▁Railway , ▁on ▁ 1 5 ▁December ▁ 1 9 5 9 ▁and ▁first ▁electric ▁train ▁run . ▁The ▁first ▁ 2 5 ▁k V ▁AC ▁EM Us , ▁for ▁Kol k ata ▁sub urban ▁service , ▁were ▁introduced ▁in ▁September ▁ 1 9 6 2 . ▁ ▁Con version ▁Consider ing ▁the ▁limitations ▁of ▁the ▁existing ▁DC ▁tra ction ▁system , ▁a ▁decision ▁was ▁made ▁to ▁convert ▁it ▁to ▁ 2 5 ▁k V ▁AC ▁tra ction ▁in ▁ 1 9 9 6 - 9 7 . ▁Con version ▁from ▁DC ▁to ▁AC ▁tra ction ▁was ▁completed ▁in ▁ 2 0 1 2 ▁by ▁Western ▁Railway ▁and ▁in ▁ 2 0 1 6 ▁by ▁Central ▁Railway . ▁With ▁this , ▁the ▁entire ▁elect r ified ▁main line ▁rail ▁network ▁in ▁India ▁uses ▁ 2 5 ▁k V ▁AC ; ▁DC ▁is ▁used ▁only ▁for ▁metros ▁and ▁tr ams . ▁ ▁Organisation ▁The ▁elect r ification ▁office ▁was ▁established ▁in ▁Cal cut ta ▁as ▁Project ▁Office ▁for ▁Railway ▁Elect r ification ▁( PO RE ) ▁in ▁ 1 9