Application of Sieyuan Electric 550 kV Disconnectors in a Brazilian Photovoltaic Project

Invested by ELECNOR BRASIL LTD, the project supports a large-scale photovoltaic power station in Brazil. The disconnectors were required to operate reliably in a 60 Hz power system and under challenging tropical and heavily polluted conditions.

Beyond standard product specifications, the project included detailed requirements for operational interlocking, control cabinets, secondary wiring, grounding, inspection, and maintenance. These requirements called for targeted customization of the disconnector and its auxiliary systems.

• Tropical and polluted environment — The equipment required enhanced external insulation performance to ensure reliable operation under tropical and polluted conditions.
• 60 Hz grid compatibility — The operating mechanism and control circuits needed to be configured for reliable operation in Brazil’s 60 Hz power system.
• Comprehensive safety requirements — Multiple electrical and mechanical locking functions were required to minimize the risk of misoperation and enhance operational safety.
• Detailed O&M requirements — The project included specific requirements for inspection, wiring, cabinet configuration, grounding, and maintenance power supply.

• Enhanced insulation and mechanical design — A 31 mm/kV specific creepage distance, composite insulators, and optimized conductor rod height were adopted to enhance external insulation performance. A two-pole angle-steel connection was adopted to improve inter-phase mechanical stability. The operating mechanism and control circuits were also configured for 60 Hz operation.
• Multi-level safety interlocking — An electromagnetic lock, padlock, and key transfer switch were integrated to provide coordinated electrical and mechanical access control. A decoupling device and arcing contact were configured to reduce erosion of the main contacts, while auxiliary switches provided clear blade-position indication.
• Maintenance-oriented design — The mechanism cabinet was equipped with transparent inspection windows and door-actuated lighting for convenient visual inspection. Enlarged control cabinets, pre-configured cables, standardized secondary wiring, OT-type terminals, and a 20 A maintenance socket were provided to simplify installation and maintenance.

• Reliable operation in harsh environments — The optimized insulation configuration provides increased insulation margin and supports reliable operation under tropical and polluted conditions.
• Enhanced operational safety — The multi-level interlocking system provides coordinated electrical and mechanical access control, helping minimize the risk of misoperation.
• Maintenance-friendly configuration — The maintenance-oriented cabinet and auxiliary configuration improve inspection efficiency and simplify routine O&M activities.