Regulatory Investment Tests for Distribution

Under Clause 5.17 of the National Electricity Rules (NER), Jemena and other distributors are required to undertake Regulatory Investment Tests for Distribution (RIT-Ds) for some network investment projects to support consistent, clear and efficient planning processes within the National Electricity Market. Below you’ll find more information on RIT-D projects that have been completed or are currently underway.

Augmentation project RIT-Ds

Jemena has completed the following augmentation project RIT-Ds. These projects are currently under construction and are expected to be completed in 2019:

Replacement project RIT-Ds

Jemena is currently undertaking the following replacement project RIT-Ds:

The following table includes a list of replacement projects excluded from the RIT-D process because they satisfy the criteria for a committed project as defined in the AER’s RIT-D Application Guidelines on or prior to 30 January 2018. These projects have been identified in Jemena’s Distribution Annual Planning Reports from 2014 onwards.

Project Name

Project Description

Scheduled Completion

Fairfield Zone Substation transformer replacement

Fairfield Zone Substation (FF) comprises three 22/6.6 kV 10/13.5 MVA transformers and three 6.6 kV buses supplying six Jemena 6.6 kV feeder lines. The substation also supplies six CitiPower 6.6 kV feeder lines. FF supplies areas of Fairfield, Alphington and Ivanhoe.

The existing FF transformers were manufactured in 1955. Due to the age and condition of the transformers, as confirmed by paper samples taken from the winding leads of the No.1, No.2 and No.3 transformers in 2013 and 2014, the transformers require replacement to maintain acceptable levels of supply reliability.

To manage the risk associated with the aging transformers at FF, Jemena will be replacing two of the transformers with 12/18 MVA 22/11/6.6 kV dual secondary winding units. The existing No. 3 10/13 MVA transformer will be retained as a hot spare.

July 2019


Preston Conversion Stage 6

Preston Zone Substation (P) comprises two 66/6.6 kV 20 MVA transformer and two 6.6 kV buses supplying five 6.6 kV feeder lines. P supplies areas of Preston. P was originally commissioned in the late 1950s. Due to the age and poor condition , many of the zone substation assets require replacement over the next five to ten year period to maintain acceptable levels of safety and supply reliability.

To ensure continued reliability and to avoid inefficient maintenance works and like-for-like replacements of poor condition zone substation components over the next five to ten years, Jemena developed a strategic plan to convert its distribution network from 6.6 kV to 22 kV in the Preston and East Preston. The conversion program commenced in 2008 and is planned to be completed in stages by around 2023.

The P conversion stage 6 project involves decommissioning the existing Preston Zone Substation and establishing a new Preston Zone Substation (PTN) consisting of two 66/22 kV 20/33 MVA transformers on the existing site.

November 2019

Essendon Zone Substation transformer replacement

Essendon Zone Substation (ES) comprises two 66/11 kV 20/27 MVA transformers and two 11 kV buses supplying ten 11 kV feeder lines. ES supplies areas of Essendon, Moonee Ponds, Ascot Vale and Niddrie.

The existing ES transformers were manufactured in 1965.  Due to the age and condition of the transformers, as confirmed by a paper sample degree of polymerisation test conducted on the No.1 transformer in 2013, the transformers require replacement within the forward planning period to maintain acceptable levels of supply reliability. The two transformers will be replaced with 66/11 kV 20/33 MVA modern equivalent units.

November 2019