Why is standard bare copper rarely used in cables rated above 150℃?

Bare copper oxidizes rapidly at elevated temperatures, leading to increased electrical resistance, brittle conductors, and eventual termination failure. In the international market, high-temperature cables utilize strictly plated conductors:

Tinned Copper: Standard for general silicone cables up to 150℃.

Silver-Plated Copper (SPC): Provides excellent conductivity and prevents oxidation; the standard for FEP and PTFE cables up to 200℃ – 250℃.

Nickel-Plated Copper (NPC): Withstands extreme heat up to 450℃+$ without oxidizing. Mandatory for MGT and TGGT cables.