Siemens SI 7 MVA Tasnetworks STATCOM Transformers

When Siemens Ltd required a specialized transformer for TasNetworks' STATCOM system in Tasmania, Hunter Transformers was engaged to deliver two high-performance 7 MVA 22/0.630 kV dual-secondary units engineered for grid stability and voltage support across Tasmania's power network. These hermetically sealed transformers, featuring two independent 3.5MVA secondary windings in Dyn11yn11 configuration, represented our first collaboration with the international Siemens brand—a partnership forged during a time of critical need that demanded exceptional engineering standards and comprehensive technical documentation.

Engineering for Four Decades of Reliable Service

The transformer was engineered with an extraordinary 40-year design life, incorporating conservative design measures and premium corrosion protection to ensure long-term reliability in Tasmania's challenging coastal climate. Specified to C4 corrosion category with RAL7033 grey finish (equivalent to Australian Standard N35), every aspect of the design prioritised durability and maintainability. The hermetically sealed construction eliminates the conservator tank while maintaining full accessibility for dissolved gas analysis (DGA) sampling—a critical requirement for TasNetworks' two-year condition monitoring program. Hunter Transformers developed specialized oil sampling procedures and integrated a 12mm BSP ball valve assembly to enable routine DGA testing without compromising the sealed integrity of the unit.

The complex bushing arrangement presented significant engineering challenges, with extensive cable connections requiring precise layout optimization. The LV cable boxes were designed to accommodate 6-8 power cables of 300-400mm² per phase, with heavy-duty copper busbars and removable front covers featuring dual-side handles for maintenance access. HV bushings utilized Type C fully insulated configuration to maintain critical clearances within the compact tank design. Throughout the engineering process, our team worked closely with Siemens to address detailed technical requirements—from WTI CT ratio specifications (400/5A on Phase A) to marshalling box internalization with integrated thermostat-controlled heaters, pressure relief valve contacts for protection coordination, and comprehensive earthing arrangements.

Collaborative Partnership and Technical Excellence

Throughout this project, Hunter Transformers demonstrated a level of technical rigor and documentation standards befitting collaboration with an international engineering leader. From initial GA drawing submissions through multiple revision cycles, our team maintained responsive communication and meticulous attention to customer requirements. Sales Manager Steve Kendall and Electrical Engineer Bill Song worked in close partnership with Siemens' project team, addressing technical queries ranging from bushing clearances and cable box panel weights to paint specifications and sampling valve configurations.

Recognizing the value of our customers' time while maintaining transparency in quality assurance, we introduced an innovative video FAT approach for this project. Rather than requiring witness attendance at factory testing overseas, Hunter Transformers developed comprehensive video documentation of each Factory Acceptance Test. This methodology captured environmental conditions, test connections, and real-time instrument readings in clearly labeled segments synchronized with written test reports. The approach transformed what traditionally requires four hours of on-site witnessing into an efficient 15-minute video review with optional Teams meetings for live technical discussion—delivering complete transparency while respecting engineering resources. The FAT was successfully conducted in September 2023, maintaining project schedules and demonstrating our commitment to innovative quality assurance methods.

Supporting Australia's Power Network Infrastructure

Our successful delivery of this specialized STATCOM transformer for TasNetworks demonstrates Hunter Transformers' capability to meet the exacting standards of international engineering firms and critical power infrastructure projects. Engineered to withstand greater electrical and thermal stress with minimal wear over its 40-year design life, this transformer now serves as a vital component of Tasmania's grid stability infrastructure—supporting voltage regulation and power quality across the island state's network. Through this collaboration with Siemens, we are proud to contribute to Australia's energy security and grid reliability, reinforcing our commitment to engineering excellence, long-term performance, and the partnerships that strengthen our nation's electrical infrastructure.