Calculate the geometric mean radius (GMR) of solid, stranded and bundled conductors from radius, diameter, AWG or kcmil, plus GMD, inductance and reactance.

Required: conductor radius, diameter, AWG or kcmil, plus the construction type.

K is the GMR to outer radius ratio (IEC 60287-1-3 Table 1).

Geometric Mean Radius Formula

The following two example problems outline the steps and information needed to calculate the Geometric Mean Radius.

GMR = .7788 × r

Variables:

  • GMR is the Geometric Mean Radius (mm)
  • r is the solid conductor radius (mm) 

To calculate the geometric mean radius (GMR), multiply the solid conductor radius by .7788.

How to Calculate Geometric Mean Radius?

The following steps outline how to calculate the Geometrics Mean Radius.

  1. First, determine the solid conductor radius (mm). 
  2. Next, gather the formula from above = GMR = .7788 * r.
  3. Finally, calculate the Geometric Mean Radius.
  4. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

solid conductor radius (mm) = 15

GMR = .7788 * r = ?