Thermal Effect on Carbon Nanotube Fiber High-Ampacity Conductors at High Frequencies

Abstract

Thermal effects on a high frequency resistance of a high-ampacity conductor based on Carbon Nanotube Fibers (CNTF) yarn is presented in this paper. AC resistances of the CNTF yarn conductors are modelled as function of frequency and temperature considering the manufacturer specifications of the CNTF yarn conductors. Also, the model is applied on copper (Cu), and then both of the results from Cu and CNTF yarn conductors were compared. The thermal effects on both conductors are verified at high frequency operation using experimental results. Firstly, the DC resistance is measured to verify the temperature coefficient for both Cu and CNTF yarn conductors. Then, the AC is also measured to compare. The results show that the calculated AC resistance values at different temperatures and frequencies match the measured values for both CNTF yarn and Cu conductors. Rate of the resistance increase in CNTF yarn with the temperature is lower than that of Cu, because CNTF yarn has the lower temperature coefficient ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\alpha }$ </tex-math></inline-formula> ). The AC resistances for both CNTF yarn and Cu decrease with increasing the temperature due to the increase in the skin depth ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\delta }$ </tex-math></inline-formula> ). The hardware test verifies that CNTF yarn’s skin depth is significantly larger than Cu, and the increasing rate of the AC resistance with temperature in CNTF yarn is lower than Cu. Therefore, employing CNTF yarn as high-ampacity conductors is advantageous due to the high thermal stability compared to Cu conductors.