Measurement of resistance temperature characteristics of graphite based flexible grounding body with current heating voltammetry

Abstract

The resistance temperature characteristics and thermal stability of graphite based flexible grounding materials were studied. With the method of current heating and constant temperature protection, the resistance of grounding body at each temperature was measured by voltammetry, and the average resistance temperature coefficient was derived. With the resistance temperature characteristic parameters of the grounding body obtained from the experiment, the maximum temperature rise of the graphite based flexible grounding body under the power frequency grounding fault current and lightning impulse current was calculated iteratively, which is verified by the calculation of the thermal stability coefficient. The experimental results show that the graphite based flexible grounding body has a negative temperature coefficient. When the maximum allowable service temperature of the graphite based flexible grounding body is 450 ℃, the maximum allowable current under 0.5 s power frequency current is about 1.4 kA, which is 8/20 μs the maximum allowable passing current amplitude of graphite based flexible grounding body under the impact of high frequency lightning current is 287.9 kA.

Keywords

• graphite based flexible grounding body
• resistance temperature characteristic
• current heating voltammetry
• resistance temperature curve
• thermal stability verification