The terms “surge arrester” and “lightning arrester” are often used interchangeably in the electrical industry. Both refer to protective devices used to limit dangerous overvoltages, but the terminology reflects different historical applications. Modern power systems mainly use metal-oxide, especially zinc-oxide (ZnO), arresters to limit transient overvoltages caused by lightning and switching operations.

A surge arrester is connected between an energized conductor and ground to limit transient overvoltage and divert surge current safely to ground. Under normal operating voltage, a modern metal-oxide arrester has high resistance and carries only a small leakage current. When a surge occurs, its nonlinear resistance decreases rapidly, allowing current to flow while limiting the voltage across protected equipment. Surge arresters are widely used in substations, transmission and distribution systems, cable systems, transformers, switchgear, and industrial networks.

“Lightning arrester” is a traditional term for a device intended primarily to protect electrical equipment from atmospheric overvoltages caused by lightning. Older lightning arresters often used spark gaps and related technologies. Modern metal-oxide devices have replaced many of these designs. The term remains common in industry and may refer to a modern surge arrester when lightning protection is the main concern.

The key difference is mainly terminology and historical application. “Surge arrester” is the broader modern engineering term and generally covers protection against both lightning surges and switching surges. “Lightning arrester” traditionally emphasizes lightning-generated overvoltages. In modern power systems, a metal-oxide surge arrester can perform both functions.

Modern metal-oxide arresters use zinc-oxide varistor blocks with a highly nonlinear voltage-current characteristic. At normal voltage, resistance is high and leakage current is low. During a transient, conductivity increases sharply, allowing surge current to be diverted to ground and limiting the voltage applied to protected insulation. Gapless metal-oxide arresters provide fast and predictable protection and are widely used in modern AC power systems.

Typical installation points include power transformer terminals, substation switchgear, transmission and distribution lines, cable terminations and transition points, generator and motor systems, industrial electrical installations, and renewable-energy power systems. The arrester should be installed close enough to the protected equipment to effectively limit transient voltage stress.

For modern technical documentation, “surge arrester” is generally the clearer term because it covers protection against more than lightning alone. However, “lightning arrester” remains common in product descriptions, field discussions, and older literature. When specifying equipment, engineers should focus on technical parameters such as continuous operating voltage, rated voltage, nominal discharge current, residual voltage, energy capability, installation conditions, and applicable standards.