Amending the outputs for Transpower's Bombay 110 kV bus security project

On 30 September 2013, Transpower submitted to the Commission a proposal to amend the outputs of the Bombay 110 kV bus security project.

Transpower has made the changes to outputs listed below and applied for us to approve them.

  1. Transpower installed a high impedance bus bar protection scheme, instead of the low impedance bus zone protection scheme.
  2. Transpower removed the compressor house and compressors, instead of relocating them.

During the implementation phase of the project, Transpower discovered that it could not efficiently deliver one of the approved project outputs – install the bus coupler circuit breaker - due to physical constraints at the Bombay substation site. Transpower assessed that it was less expensive to deliver an alternative solution of replacing some of the existing circuit breakers, rather than overcome the physical constraints. Transpower implemented the alternative solution and now seeks our approval to amend the project outputs. Change in outputs has not affected the level of transmission service delivered by the project.