Why are tension and temperature monitors ineffective in determining the dynamic rating for lightly loaded lines?
The rise in conductor temperature due to current is proportional to the square of current. When the current is less than 35% of the static rating, the temperature rise is less than 10% of that associated with full load. Since the line rating is calculated based on the measured equivalent temperature rise, and since errors in estimating equivalent conductor temperature rise from tension and solar temperature measurements are typically several degrees C, large errors in rating are likely to result from lightly loaded lines.
