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One and a half breaker scheme of bus bar arrangement

Schematic drawing:
  • Generally utilized in EHV sub stations (400KV and above)
  • Needs three breakers for two circuits
  • The number of breakers per circuit is 1½. Hence, the name is given as one and a half breaker scheme.
  • ½ breaker is more per circuit
  • Such arrangement is particularly suitable for switchyard   in large generating stations where very high power block is to be handled by individual circuit ( say 500MW)
  • In GEB, one and a half breaker arrangement scheme is at Wanakbori TPS on 400KV circuits.
  • In PGCIL, it is at Dehgam S/S.
  • The higher cost is justified because of higher security and bypass facility.
  • Either of the two buses (Main bus I or Main bus II) can be taken out of service for maintenance
  • Any circuit can be switched off for the purpose of maintenance without the provision of bypass
  • Bus failure does not remove any circuit from service. 

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