10kV busbar span

The span of a 10kV busbar is determined by mechanical support, dielectric clearance, and short-circuit forces, typically requiring support points calculated based on rigidity and safety standards rather than a fixed distance.

Mechanical Support and Span

The busbar span refers to the distance between support points that hold the busbar in place. For a 10kV busbar, the span must account for:

• Flexural rigidity of the busbar material (copper or aluminum)
• Short-circuit forces that can cause bending or displacement
• Thermal expansion during operation
• Mechanical resonances at mains frequency and harmonics Busbars are often supported using fixed bearings (with rubber discs) or plain bearings (metal discs) to allow axial sliding. The choice of bearing type affects the maximum allowable span between supports .

Electrical Clearance and Creepage

For medium-voltage busbars like 10kV:

• Clearance is the shortest distance through air between conductors of opposite polarity or between a conductor and ground.
• Creepage is the distance along the surface of an insulating material. ANSI and other standards do not specify a fixed spacing; instead, the design must pass dielectric and impulse withstand tests. For example, bare conductors can be placed as close as 1/2 inch if the equipment passes the required 15kV tests .

Laminated Busbar Considerations

In high-performance applications, laminated busbars are used to reduce inductance and improve transient response. For a 10kV SiC MOSFET module, laminated busbars are designed with:

• Optimized sections to minimize parasitic inductance
• Integrated DC-link capacitor banks
• Dielectric integrity verified via simulations to ensure surface electric fields remain well below insulation breakdown limits These designs also influence the mechanical span, as laminated busbars are typically segmented and supported at multiple points to maintain structural and electrical performance.

Practical Guidelines

• Support spacing should be calculated based on busbar thickness, width, and material properties.
• Short-circuit forces must be considered to prevent mechanical failure.
• Thermal expansion requires either sliding supports or segmented busbar connections.
• Insulation and clearance must meet or exceed the voltage rating (10kV) and withstand transient overvoltages. In summary, the 10kV busbar span is not a fixed value; it is determined by a combination of mechanical, electrical, and thermal factors. Designers typically use calculation programs or manufacturer guidelines to determine optimal support spacing for safe and reliable operation .