What type of cable is used in electrical power transmission?

Normally cables are not used in Power Transmission because Transmission is long distance project and cable cost goes all they way higher. Its not a wise choice to use Cables for Power Transmission. (If ever a customer decide to chose the cable as medium of power transmission, then cable selection shall depends upon the transmission voltage level, and mode of laying cables)

Transmission is done mostly overhead and is done through bare conductors as like ACSR etc.

Regards,

low losses :copper cable.

low cost :Allumunium cable.

Power transmission cable use Allumunium cable for low cost. and copper cable for low losses 

Power transmission cable (Aluminium conductor)

Coaxial cable for overhead radio transmission

i think , it is fiber optic cable,  if i am , not wrong.