True/False: ampere conductors and temperature rise

TRUE.

Specific electric loading $ac = I_zZ/(\pi D)$ is the ampere-conductors per metre of armature periphery. A higher $ac$ means more conductors (or more current) per unit surface of the armature, so the $I^2R$ copper loss per unit cooling surface increases. Since this heat must be removed through the same surface, the temperature rise increases. That is why $ac$ is limited by the cooling arrangement and the class of insulation, and machines with better ventilation (high-speed or forced cooled) can use a higher $ac$.

Example: if $ac$ is raised from 20000 to 30000 A/m with the same conductor current density, the copper volume per metre of periphery rises by 50%, so copper loss per unit surface (and roughly the temperature rise) also rises by about 50%. Typical values are 15000–50000 A/m.