Conductors and Ground Wires
Conductors are the carriers of electric energy, typically using steel-cored aluminum stranded wires for good conductivity and mechanical strength; ground wires are used for lightning protection to ensure line safety.

Towers and Foundations
Towers support conductors and ground wires. They are classified into suspension towers, tension towers, and angle towers, mostly made of reinforced concrete or steel, and must be firmly fixed to the foundation.

Insulators
Used to isolate live conductors from towers to prevent current leakage. Common types include suspension, pin, and composite insulators, widely used in overhead lines.

Fittings and Guy Wires
Fittings include suspension clamps, tension clamps, and connecting fittings, used to fix and connect conductors; guy wires enhance tower stability, especially used in angle or terminal towers.

Grounding Devices
Conducts lightning current or fault current into the earth to protect equipment and personnel safety, serving as a vital part of lightning protection and safe operation.

Transformers
Realize voltage step-up and step-down; they are the core equipment in the transmission system, converting high voltage into voltage levels suitable for long-distance transmission or user consumption via electromagnetic induction.

Circuit Breakers
Capable of connecting or interrupting circuits under normal and fault conditions, especially acting quickly during short circuits to protect the system from damage.

Isolating Switches (Disconnectors)
Provide a visible break point in the circuit to ensure maintenance safety. They have no arc-quenching capability and must be operated under no-load conditions.

Instrument Transformers (Current & Voltage Transformers)
Convert high voltage and large currents into standard low voltage and small currents for measuring instruments and relay protection devices, enabling system monitoring and protection.

Reactors and Surge Arresters
Reactors are used to limit short-circuit currents and regulate voltage; surge arresters absorb lightning or switching overvoltage energy to protect equipment insulation.

Relay Protection Devices
Monitor system status in real-time and automatically isolate faulty sections to ensure grid stability.

Communication & Automation Control Systems
Facilitate information exchange between substations and dispatch centers, supporting remote monitoring and intelligent scheduling.

Gas Insulated Switchgear (GIS)
Integrates functions like circuit breakers, disconnectors, and instrument transformers into a sealed space, suitable for space-constrained scenarios like urban substations.

China has established a UHV transmission network featuring "Three AC and Four DC" lines, widely applying new technologies such as Smart Grids and VSC-HVDC, significantly improving system efficiency and reliability.