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This is the environment surrounding the conductor. In the current version it is limited to atmospheric Air. The relevant heat dissipation mechanism to this medium is Natural Convectionand is governed by non-linear empirical correlations depending on the Rayleigh number . Here the Churchill and Chu correlation for horizontal cylinders is used.

The estimated temperatures relate therefore ONLY to conductors freely and horizontally suspended in the cooling medium (e.g. Air).

Conductors near to or within objects (walls, floors, roofs, ducts, chambers, underground, etc.) can have significantly different underlying physics** and estimated temperatures, than the freely suspended conductor.

**Because natural convection flows and also radiation (see emissivity below) are affected and/or additional thermal resistances are added.

This is the temperature of the environment surrounding the conductor. The heat sink temperature for heat dissipation through natural convection.

Here, this is also considered as the surroundings temperature for heat dissipation through radiation.

Altitude in meters above sea level. It used to estimate the barometric pressure and the atmospheric Air density at that altitude.

You can add various materials as the core conductor. The thermal evaluation considers linear temperature behavior of the electrical resistivity. The key properties are therefore the electrical resistivity at 20°C and the temperature coefficient.

Here, the typical materials of Annealed Copper and commercially pure Aluminum are listed and for comparison purposes: silver, gold.

In addition various electrical resistivities in %IACS units are listed. 100% is the reference value for annealed Copper. More on the International Annealed Copper Standard (IACS).

You can add a single layer of insulation to the conductor core. The key property is the thermal conductivity of the insulation material.

Here, typical materials of PVC (~0.16 W/m-K) and PE (~0.3 W/m-K) can be chosen, these are reference thermal conductivities and significant deviation may occur.

In addition various thermal conductivities in W/m-K units are listed. Or simple select none to evaluate a bare conductor.

.....SURPRISE yourself: add insulation to a small diameter bare conductor and see the temperatures drop....

Simply said, Direct Current (DC) uses the full cross-section of the conductor. This means the conductor sees a constant current density (Amps per unit of area, usually A/mm²). Alternating Current (AC) does not behave like this. The current density in the conductor cross-section can be affected by electromagnetic phenomena known as skin effect and proximity effect, which depend on AC frequency, conductor geometry and material, and proximity to other current-carrying conductors.

Generally, conductors are designed with multi-core strands, and are twisted to cancel out these effects- This returns an homogeneously distributed AC current density. In these cases, AC current can be treated as an equivalent DC current with a given RMS value.

Here, the input corresponds to a DC current or the RMS value of a homogenously distributed AC current.

Conductors suspended in free-standing, atmospheric Air generally dissipate their resistive losses through natural convection and radiation. Surface emissivity, a property of the surface exposed to the environment, defines the contribution of radiation as a heat dissipation mechanism. It ranges from 0 (no contribution) for a perfectly shinny (reflecting) surface, to 1 (full contribution) for a perfect black body.

A Surface emissivity value of 0.7 could be considered as representative for weathered bare or insulated Copper and Aluminum conductors. For bare shiny (new) conductors, values around 0.05 would be more suitable. Try and see the effect of different emissivity values in the estimated temperatures.