How should wind speeds be measured for line rating purposes?
For static or dynamic rating purposes, wind speeds need to be measured in the vicinity of the line being rated and the anemometers need to be accurate at wind speeds below 2 m/sec. Bearing friction needs to be considered in cup type and propeller type anemometers. Averaging periods of 5 to 15 minutes are appropriate in most cases. The measurement height for wind should be approximately the same as the low point of the line conductors. Placement of anemometers should be considered relative to sheltered areas along the line, perhaps by reducing measured wind speeds to account for sheltering.
