Sydney Metro Central Tunnelling Electrical Infrastructure

Overview

The Sydney Metro Central Tunnelling Project, part of Sydney's major metro expansion, involved constructing a new underground rail tunnel. The Acciona Ferrovial Joint Venture was tasked with delivering this critical phase, which required reliable and robust electrical infrastructure to support the tunnel boring machines (TBMs) and associated construction equipment. Key components provided included 33kV metering units, isolation transformers, RMUs (Ring Main Units), containerized switchrooms, high-voltage cables, and switchyard installation. These systems ensured continuous, safe power for tunnelling operations.

Objectives

• To deliver a continuous and reliable power supply to support TBMs, lighting, ventilation, and other essential construction equipment.
• To design and implement a safe and flexible electrical system capable of meeting the high demands and unique challenges of underground tunnelling.
• To provide a modular and adaptable electrical infrastructure that could scale as project requirements evolved.

Key Deliverables

• 33kV Metering Units:
  • Objective: Provide accurate metering of incoming 33kV power for monitoring and control.
  • Execution: 33kV metering units were installed to monitor energy consumption and ensure efficient distribution, allowing for real-time tracking of power usage.
• 33kV/11kV Isolation Transformers (4MVA, 2MVA):
  • Objective: Step down the high-voltage supply (33kV) to 11kV and provide electrical isolation.
  • Execution: Isolation transformers rated at 4MVA and 2MVA were deployed to safely distribute power to the tunnelling operations, ensuring isolation between the high-voltage grid and the underground systems.
• NER (Neutral Earthing Resistor):
  • Objective: Provide fault protection and system stability by controlling fault currents.
  • Execution: NERs were installed to ensure safe grounding and to dissipate fault currents, providing added protection to both the system and workers.
• RMU (Ring Main Unit):
  • Objective: Ensure the reliability of the power distribution network.
  • Execution: RMUs were deployed to manage power distribution, facilitate the isolation of faults, and maintain consistent electrical flow to essential equipment.
• 11kV/415V Containerized Switchrooms (500kVA, 1.5MVA, 2MVA):
  • Objective: Provide flexible and scalable power distribution through modular containerized substations.
  • Execution: Containerized switchrooms were set up to house transformers and switchgear, with 500kVA, 1.5MVA, and 2MVA options, offering adaptability as power needs fluctuated.
• High Voltage Cable:
  • Objective: Ensure the safe transmission of power to critical tunnel equipment.
  • Execution: Specialized high-voltage cables were used to transmit power to TBMs and other machinery, guaranteeing stable operations even in the harsh underground environment.
• Switchyard Installation:
  • Objective: Provide a central location for controlling and protecting electrical circuits.
  • Execution: A switchyard was installed to safely manage power circuits, isolate faults, and allow for easy maintenance while keeping the system operational.

Outcome

The Sydney Metro Central Tunnelling Project successfully integrated the electrical infrastructure provided for the Acciona Ferrovial Joint Venture. The 33kV metering units, isolation transformers, RMUs, containerised switchrooms, and high-voltage cable installation delivered continuous and reliable power, ensuring that tunnelling operations proceeded without interruption.

The modular, flexible design of the electrical system allowed it to adapt to the evolving needs of the project, while the high-voltage protection measures ensured both operational safety and efficiency. The integration of switchgear and earthing systems contributed to maintaining safety standards throughout the tunnelling process.

With the electrical infrastructure operating seamlessly, the project maintained its schedule, meeting both operational and safety goals, and positioning the Sydney Metro Central Tunnelling Project for continued success.