Can a small busbar be used in a 35kV high-voltage switchgear

The number of small busbars in a 35 kV switchgear depends on the configuration, typically ranging from one in single-bus systems to multiple in double-bus or sectionalized arrangements.Busbar ConfigurationsIn 35 kV high-voltage switchgear, busbars are used to distribute power to multiple feeders and ensure operational flexibility. The number of small busbars is not fixed and depends on the system design:Single Bus Configuration: One main busbar carries the current to all feeders. Small busbars may be used internally for connections to individual circuit breakers or instrument transformers, usually one per phase per feeder .Double Bus Configuration: Two main busbars allow for maintenance or sectional operation without interrupting supply. Each section may have its own small busbars connecting feeders to the main buses .Bus Sectionalizing: In larger installations, sectionalizing busbars divide the system into segments, increasing the number of small busbars to allow isolation of parts of the switchgear for maintenance or fault management .Design ConsiderationsVoltage and Current Ratings: For 35 kV switchgear, busbars must handle continuous currents typically between 1250–3150 A, with short-circuit withstand ratings of 25–40 kA .Insulation and Clearance: Small busbars are often insulated or enclosed to maintain safe clearances according to IEC standards, preventing arcing and ensuring operator safety .Operational Flexibility: The number of small busbars increases with the need for redundancy, future expansion, or the ability to isolate feeders without interrupting the entire system .Practical ExampleA typical 35 kV gas-insulated switchgear (GIS) may have:One main bus per phase in a single-bus system.Two main buses per phase in a double-bus system.Additional small busbars connecting each feeder or circuit breaker to the main bus, often totaling 3–6 small busbars per feeder section depending on the design .ConclusionThere is no universal number of small busbars in 35 kV switchgear; it varies with the bus configuration, number of feeders, and operational requirements. For a single-bus system, expect one small bus per feeder per phase, while double-bus or sectionalized systems will have multiple small busbars to allow flexible operation and maintenance. Proper design ensures compliance with IEC standards for insulation, clearance, and fault withstand.