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Loading

The Loading class defines the mechanical loading profile applied to a conductor, including wind pressure, ice thickness, and temperature conditions that affect sag and tension calculations.

Fields

Field Type Default Description
wind_ice_temperature_c float — Temperature at which wind and ice loading occurs (°C, –60° to 60°)
pressure_pa float 0 Wind pressure on conductor (Pa)
ice_thickness_m float 0 Radial ice thickness on conductor (m)
ice_density_kg_per_m3 float 0 Density of ice accumulation (kg/m³)
additive_loading_n_per_m float 0 Additional mechanical loading (N/m)

Standard Loadings

NESC 250B loading scenarios are provided. 

    from refa.standards import nesc_250b_heavy

    loading = nesc_250b_heavy()
    # wind_ice_temperature_c=-10°C...

Custom Loading

Start from a default and modify

loading = nesc_250b_heavy()
loading.wind_ice_temperature_c=-15.0
loading.pressure_pa=750.0

Or construct:

from refa import Loading

loading = Loading(
    wind_ice_temperature_c=-5.0,
    pressure_pa=500.0,
    ice_thickness_m=0.010,
    ice_density_kg_per_m3=900.0,
)

Loading combinations

The Loading class allows independent specification of wind pressure and ice accumulation. In practice, these may occur together (e.g., wind-on-ice scenarios) or separately. Use pressure_pa for wind loading and ice_thickness_m + ice_density_kg_per_m3 for ice loading.

Effect on Calculations

The Loading directly affects sag and tension calculations in Line. Changing the loading profile will change:

  • Conductor sag at the specified temperature
  • Tension required to support the combined weight

LoadingImperial

In case of imperial unit system, the user can use the same constructor Loading, which will accept values in imperial units. These are converted to metric system with which all internal calculations are conducted.

| metric name —> imperial name | | wind_ice_temperature_c —> wind_ice_temperature_f | | pressure_pa —> pressure_lb_per_ft2 | | ice_thickness_m —> ice_thickness_in | | ice_density_kg_per_m3 —> ice_density_lb_per_ft3 | | additive_loading_n_per_m —> additive_loading_lbf_per_ft |