Connection of busbar bridge and small busbar in high-voltage switchgear

In high-voltage switchgear, a busbar bridge connects main and small busbars using dedicated connectors, ensuring reliable current flow, mechanical stability, and safe maintenance.

Busbar Bridge Function

A busbar bridge serves as a conductor linking the main busbar to smaller branch busbars or auxiliary circuits. It allows power to be distributed from the primary bus to secondary circuits while maintaining electrical continuity and minimizing voltage drop. The bridge ensures that the system can handle the rated current without overheating or excessive mechanical stress during short-circuit events.

Connection Methods

Material Compatibility: Copper-to-copper connections typically use bronze connectors to enhance contact reliability and prevent creep relaxation. Aluminium-to-aluminium connections use treated aluminium alloy connectors to maintain oxide film stability. Copper-to-aluminium connections require bi-metallic connectors (e.g., explosive welding or brazing) to prevent electrolytic corrosion.

Mechanical Support: Busbar bridges are supported by insulators or brackets to withstand mechanical stresses from short-circuit forces. Tubular or flat busbars are commonly used, with tubular types offering higher mechanical strength and better corona resistance. Insulation and Safety: Bare busbars rely on air insulation, while enclosed or insulated busbars reduce short-circuit risk and allow compact layouts.

Proper spacing and support prevent overheating and electrical faults, ensuring safe operation during maintenance.

Operational Considerations

Flexibility: Busbar bridges allow sectionalization, enabling parts of the switchgear to be isolated for maintenance without interrupting the entire system. Current Rating: The bridge and small busbar must be sized to carry the expected load, considering thermal performance and short-circuit withstand capacity. Maintenance: Connections should inhibit corrosion and oxidation to maintain low contact resistance and prevent overheating.

Summary

Connecting a busbar bridge to a small busbar in HV switchgear involves selecting compatible materials, using appropriate connectors, providing mechanical support, and ensuring proper insulation. This ensures reliable power distribution, operational flexibility, and safe maintenance, while meeting the electrical and mechanical requirements of high-voltage installations.