Technical Data of Heathing Cables

In order to calculate the start-up current of the heating cable, you must adjust conductor resistance value according to environment temperature; specific cable resistance is proportional to temperature gap,as shown in the following relationship:

Rt = R20 · [ 1 + α ( t - 20 ) ]


where:

  • Rt = resistance at t temperature
  • R20 = resistance at 20 °C temperature
  • t = operating temperature
  • α = temperature coefficient


α and [1 + α(t - 20)] values are reported on the tables below:

 

Conductor Type Resistivity at 20 °C α coefficient
Copper (C) 1.72 μΩcm2/cm 0,004
Kumanal (K)  41.0 μΩcm2/cm 0
Nickel/Chrome 80/20 (T) 113 μΩcm2/cm variable

 

 Copper (C)

Temperature °C 20 40 60 80 100 150 250
[1 + α(t - 20)] 1 1.08 1.16 1.24 1.32 1.52 1.92

 

 Kumanal (K)

Temperature °C from 20 to 350 °C
[1 + α(t - 20)] 1

 

 Nickel/Chrome 80/20 (T)

Temperature °C 20 200 200 400 600 800
[1 + α(t - 20)] 1 1.019 1.035 1.063 1.066 1.062

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