Rayo was engaged by ElectraNet to deliver the complete design and construct replacement of Transformer 1 at the Mannum Substation — a critical asset on South Australia’s high-voltage transmission network.
The scope integrates Rayo’s in-house high-voltage specialists with Tier 1 engineering partner APD and trusted subcontractors under a single management framework, giving ElectraNet clear scope ownership and disciplined coordination across design, civil, electrical and commissioning.
ElectraNet owns and operates South Australia’s high-voltage electricity transmission network. As a critical infrastructure operator managing the grid’s transition to renewable energy, ElectraNet continuously renews aging assets to maintain reliability while supporting increased solar and wind generation.
The Mannum Transformer 1 replacement forms part of ElectraNet’s ongoing programme to replace end-of-life transformers and modernise substation infrastructure across the network. The Mannum Transformer 1 has been in service for 61 years and has been assessed to be at the end of its technical life.
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The Mannum Substation is a transmission-level asset. Transformer replacement at this voltage demands precise coordination of design, civil works, high-voltage electrical works and commissioning, executed within network outage constraints and to ElectraNet’s engineering specifications.
Rayo’s delivery model combines APD’s Tier 1 engineering, in-house HV expertise and trusted subcontractors under one framework, with executive-level engagement throughout. Rayos model offers a turn key solution, from design and engineering, to in house transformer assemble, HV testing and secondary commissioning.
Rayo structured the works around a single integrated management framework — APD Tier 1 engineering, in-house HV specialists and trusted subcontractors — giving ElectraNet a single point of accountability across design, civil, electrical and commissioning.
The team applied deep site familiarity from the earlier Transformer 2 emergency replacement at Mannum and drew on recent transformer works at Tailem Bend (Hitachi Energy) and Burronga (Elecnor) delivered by the same core personnel. Key personnel include Liam Casey (General Manager — commissioning and HV operations lead), Lucas Marsh (General Manager SQE, on site for a significant portion of the works), Ben Speer (Construction Supervisor and HV Testing Lead) and Meedo El Hamra (Civil Design Engineer), Andrew Baker, (General Manager – Operations and Maintenance)
Delivery was planned around the network outage window, with outage management, hazard-register review and sequencing controlled through an MS Project programme.
Safety was managed through Rayo’s ISO-aligned SQE system and a Critical Risk Framework informed by Safety-II and Human and Organisational Performance principles: a substation “Buddy System” pairing lower-exposure workers with the most experienced Access Supervisor, an inclusive pre-start induction covering all personnel including delivery drivers and short-term visitors, and a full-time Site Supervisor with a Safety Adviser present for all high-risk construction and lifting activities. Major outdoor construction and lifting works were deliberately scheduled into the March weather window, where Copernicus rainfall data for Mannum and Tailem Bend (2017–2022) shows the lowest precipitation of the year — 8–9 mm across one to two rain days.
Rayo brought direct, recent experience of this exact asset — the same core team delivered the emergency replacement of Mannum Transformer 2 — combined with a broader South Australian transmission track record and a Tier 1 engineering partnership.
For ElectraNet, that meant a delivery partner that is safe, technically robust and tailored to the site: agile, solutions-focused and backed by consistent executive-level engagement.
OEM-standard transformer and high-voltage expertise, delivered with Tier 1 engineering partner APD and Rayo’s in-house HV specialists, aligned to ElectraNet’s engineering contract specifications — including full primary and secondary design, fire and explosion assessment, noise modelling and lightning protection review to AS/NZS 1768. The same construction team delivers transformer assembly, pre-commissioning and primary plant testing, and the same commissioning team delivers protection testing, SCADA site works, switching and energisation — limiting mobilisations and removing siloed handovers.
A dedicated Project Management Office controlling programme, procurement, cost, quality and interfaces, with Rayo as principal contractor across five delivery partners (APD, GE Hughes, Delta, Fleurieu Cranes, Haymans). Outage planning was led directly by Rayo’s General Manager with ElectraNet’s PSO team, with switching, isolation and energisation sequencing built into the Commissioning Management Plan and a live, risk-adjusted MS Project schedule.
A senior team that has delivered transformer works across South Australia’s transmission network —
Liam Casey (General Manager, 15+ years commissioning national HV assets), Andrew Baker (General Manager, 20+ years High Voltage experience) Lucas Marsh (General Manager SQE), Brayden Sommers (Construction Supervisor and HV Testing Lead) and Meedo El Hamra (Civil Design Engineer).
An ISO-certified Safety, Quality and Environmental framework (ISO 9001 / 14001 / 45001) plus CM3 accreditation, led by senior personnel with hands-on site presence — Rayo’s most senior SQE leader on site for a significant portion of the works — with quality built in through ITPs, hold and witness points, and whole-of-lifecycle cultural heritage and native title management.