Installation of 35kV busbar structure in substation

35kV substation busbar installation must comply with national standards, proper material selection, precise sizing, secure support, and thorough inspection to ensure safety, reliability, and operational efficiency.

Busbar Design and Material Selection

Busbars in 35kV substations serve as the main conduits for power distribution and must be designed to handle expected current loads with minimal energy loss. Copper is preferred for high-current applications due to its superior conductivity and durability, while aluminum may be used where cost and weight are critical factors . Busbar sizing should consider the permissible temperature rise, short-circuit current, and mechanical strength requirements . Rectangular or slotted busbars are commonly used, and their surfaces must be flat, smooth, and free of sharp edges or burrs to prevent electrical stress and corona discharge .

Busbar Configurations

Common 35kV substation busbar arrangements include Single Bus, Main and Transfer, Double Bus/Double Breaker, Ring Bus, and Breaker-and-a-Half configurations. The choice depends on substation criticality, load requirements, and desired operational flexibility . For substations with multiple transformers, single bus sections with proper load distribution are recommended, and short-circuit current limiting measures may be applied using high-impedance transformers or series devices .

Support and Insulator Installation

Busbars must be mounted on sturdy support brackets and insulated using suspension or post insulators. Brackets and insulators should be secure, aligned, and free from rust or defects, with all bolts tightened and continuity verified . Wall penetration sleeves must be smooth, crack-free, and properly grounded, ensuring no closed magnetic circuits are formed .

Grounding and Overvoltage Protection

Grounding design should comply with DL/T 621 and relevant lightning protection standards (GB 50057). Overvoltage protection must follow DL/T 620, ensuring that surge arresters and voltage transformers are correctly connected, with isolating switches where required . Proper grounding of busbars, supports, and protective nets is essential for personnel safety and equipment protection .

Inspection and Acceptance

Installation must undergo visual and mechanical inspections, including flatness, alignment, surface quality, and dimensional checks using rulers or vernier calipers. Material composition should meet standards (Copper ≤3%, Aluminum ≤5%), and all connections must be secure and conductive . Protective nets and barriers should be sturdy, uniform, and reliably grounded.

Layout and Safety Considerations

Substation layout should consider load centers, environmental conditions, seismic design, and fire safety. Main roads must meet fire protection requirements (minimum 4.0m width), and equipment placement should allow for maintenance and minimize noise impact . Busbar arrangements should facilitate maintenance without power interruption and provide redundancy for critical loads . By adhering to these standards, 35kV substation busbars can achieve high reliability, operational safety, and compliance with national and industry regulations.