Driven by the goal of building a new-type power system

the high penetration of renewable energy and widespread application of power electronic devices have posed severe challenges to the thermal reliability of power transmission and distribution (T&D) equipment. The development trend towards high voltage

large capacity

and high power density has made temperature a critical bottleneck

constraining the insulation lifetime

operational safety

and transmission capacity of the equipment. This paper presents a comprehensive overview of the heat transfer mechanisms

research methodologies

and application scenarios in T&D equipment on the basis of the classical framework of conduction

convection

and radiation. At the mechanism level

conduction issues such as anisotropic heat conduction

thermal contact resistance

and thermal interface materials are discussed. The physical models for complex convective phenomena

including turbulence

porous media flow

and phase change heat transfer

are summarized. Furthermore

the application of radiative cooling technology in power equipment is introduced. In terms of methodologies and applications

analytical tools

including flow field diagnostic techniques

numerical simulations

and machine learning

are categorized. The critical role of heat transfer analysis throughout the equipment’s life cycle

including optimal design

fault diagnosis

and dynamic rating

is also summarized. Finally

prospects in future research directions are put forward

including heat transfer in power equipment under extreme conditions

the development of physics-informed machine learning

and the construction of equipment digital twins.