Automatic Working of Circuit Breaker in Neutral Section

Abstract

Power is generated and transmitted using three phase a. c. supply in India. AC Traction system in India uses 25kV, single phase for its operation. Traction system consumes a large amount of power for its operation. The Overhead Equipment of railways which is single phase AC, is fed from a three-phase transmission network using substations located at regular intervals. This may lead to an unbalance in the voltage of the system. To avoid this unbalance and to maintain stability in supply network and reliable operation of the power system as well as the traction system the overhead equipment’s are fed from three phase supply by a consecutive change of the phase. The overhead equipment is fed from (say) R-phase for a distance of about 45km then by B-phase and then by Y-phase and the cycle continues. These sections of each phase are insulated from each other using an insulator. This insulator section is called Neutral Section and is made of materials like PTFE (poly tetra flouro ethylene), resin bonded glass fibers core protected with wear resistant ceramic beads, etc. this section is also called as dead section. In initial stages of development of AC traction, the pantograph used to be lowered during this neutral section. Nowadays with the development of science, the pantograph slides smoothly through the neutral section and is not lowered. The locomotive is disconnected during the neutral section to avoid occurrence of fault, transient disturbances and sparking lead to a fault. For this purpose, the motorman operates the circuit breaker manually and switches off the locomotive. The aim of our project is to automate this operation of circuit breaker in electrical locomotives which will lead to reduction in losses due dead time of loco in neutral section.