High-Seismic-Performance 550 kV Instrument Transformers for a Transmission Hub Project in Peru

As part of Peru’s 2017–2026 National Transmission Plan, the project strengthens high-voltage transmission infrastructure in northern Peru. The region’s seismic activity and coastal climate placed stringent requirements on equipment selection, with particular emphasis on seismic performance, environmental resistance, and long-term reliability.

• 0.5 g seismic qualification — Strong seismic activity in Peru places high mechanical demands on tall instrument transformers. The project required the equipment to meet a 0.5 g seismic rating in accordance with IEEE 693, validated by full-scale shake-table testing.
• Coastal salt spray and humidity — High humidity and salt spray in Piura and Tumbes increase the risk of corrosion and sealing degradation, requiring enhanced protection for exposed components and critical joints.
• Multi-type batch supply — The project covered four instrument transformer types with different structural and testing requirements, requiring consistent engineering, manufacturing, and quality control across 157 units.

• Seismic-resistant structural optimization — Sieyuan optimized porcelain bushing strength, flange connections, center-of-gravity height, and base stiffness through seismic, electric-field, and thermal simulations. Cemented connections between porcelain bushings and metal components enhance structural integrity and reduce stress concentration under seismic loading.
• Full-scale shake-table validation — Sieyuan conducted full-scale shake-table tests using seismic time-history curves in accordance with IEEE 693. Critical acceleration and strain responses were monitored, followed by post-test inspection. No damage was identified in the porcelain bushings, cemented joints, or internal windings, and formal seismic qualification reports were obtained.
• Corrosion protection and batch quality control — Aluminum alloy was used for exposed metal components to improve salt-spray resistance. For CTs, robotic argon-arc welding formed integrated, gasket-free oil-reservoir joints, reducing gasket-related sealing risks. Standardized manufacturing and quality control ensured consistency across the 157-unit batch.

• 0.5 g full-scale seismic qualification — Physical shake-table testing verified the equipment’s seismic performance in accordance with IEEE 693, with formal qualification reports provided.
• Porcelain-to-metal cemented joint technology — Cemented joints between porcelain bushings and metal components enhance structural integrity under seismic loading.
• Gasket-free welded structure — Robotic argon-arc welding integrates CT oil reservoirs and reduces gasket-related sealing risks.
• Aluminum-alloy corrosion protection — Exposed metal components were optimized for the project’s coastal salt-spray and high-humidity conditions.