With 800V platforms, liquid-cooled fast charging and denser AI server power supplies, connector competition has moved beyond current carrying and temperature rise: CTI, the comparative tracking index of insulation materials, has become a hard design and selection criterion.
CTI reflects how well an insulating plastic resists surface tracking under wet and contaminated conditions; higher values make conductive carbon paths harder to form. Under IEC 60112, material group I corresponds to CTI of 600 or above, but the standard test voltage tops out at 600V AC, so CTI is not a rated working voltage.
Insulation coordination requires evaluating clearance, creepage and solid insulation together, along with pollution degree, overvoltage and altitude. High-CTI materials create room to optimise creepage but do not justify reducing clearance or wall thickness. The article also notes that domestic high-CTI materials must still prove batch consistency, long-term ageing data and full vehicle validation.
Compiled by the committee. Data and conclusions follow the original sources; please credit when republishing.
Source：International Cable & Connector (Big-Bit) · Advanced Basic Materials Committee
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