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Elctrical Resistivities & Temperature Coefficients

The following table is taken from IEC 60287-1-1:2006 "

 

 
Material
 Resistivity (ρ)
Ω.m at 20 °C
 Temperature Coeffiicent (α20)
K-1 at 20 °C
 - conductors  
 Copper  1.7241 10-8   3.93 10-3
 Aluminium  2.8264 10-8  4.03 10-3
 - Sheaths & Armour  
 Lead or lead alloy  21.4 10-8  4.0  10-3
 Steel 13.8  10-8  4.0  10-3
 Bronze  3.5 10-8  3.0  10-3
 Staninless steel  70 10-8  negligible 
 Aluminium  2.84 10-8  4.03  10-3

 

Comments

Ei Le Dec 12, 2018 6:45 PM
Correct that resistivity in given table is the DC resistivity in https://mycableengineering.com/knowledge-base/conductor-resistance ?

Should it be Ω/m as resistivity is proportional to length?  

How to calculate α20 when temperature in cable is changing? Possible to assumed it's constant in temperature range og 20-90 degrees celcius?
Steven McFadyen Dec 12, 2018 7:35 PM
The values are the ones you should use for d.c. resistivity and the units are Ω.m.  

For 20 to 90°C, normally people would assume α is constant.  Using a more accurate value is probably not going to make much difference (unless you are doing laboratory type experiments).

If you are interested in how α varies with temperature, an Internet search will give more information.
Ei Le Dec 12, 2018 7:52 PM
Great, thank you!

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