What do elastic coefficient and expansion coefficient mean?

Elastic coefficient is also called elastic modulus. Elastic modulus is not only an important factor affecting cable stiffness, but also an important physical quantity affecting the operating tension of overhead wire and cable. The elastic modulus of overhead conductor is not only related to the material, but also closely related to the structure of conductor, such as the number of strands of conductor and the process parameters of strand. 

The exact elastic modulus of conductor should be determined by tensile test, so it is often said that there are initial and final values, while the test report often only gives "measured values".

The coefficient of expansion is sometimes called linear elasticity, which refers to the percentage of the change in the length of the material for every 1 ℃ change in temperature, also known as the coefficient of linear expansion. When the temperature of a solid substance changes by 1 ℃, the ratio of the change of its length to its length at 0 ℃ is called "coefficient of linear expansion".

Due to different substances, the linear expansion coefficient is also different, and its value is also related to the actual temperature and the reference temperature selected when determining length 1. However, because the linear expansion coefficient of solid changes little, it can be ignored, and a is regarded as a constant independent of temperature.