These new sections provide direct comparisons and mathematical formulas to convert old line discharge classes into modern charge classifications.

The 2018 revision introduced a major shift to align with the testing protocols of IEC 60099-4:2014. The most significant change is the move from to a Charge/Energy-Based Classification .

Including series and parallel gapped arresters rated ≤is less than or equal to 52 kV per IEC 60099-6 .

Selection workflows now place heavier emphasis on maximum residual voltage as the primary parameter for insulation coordination.

Annex D was updated to include modern service monitoring techniques, such as leakage current measurement with harmonic compensation.

Instead of the old "Class 1 to 5" system, arresters are now classified by their thermal energy dissipation and repetitive charge transfer capability ( Qrscap Q sub r s end-sub

The IEC 60099-5 standard provides non-mandatory but highly recommended guidelines for the selection of surge arresters in three-phase systems with nominal voltages . It covers several specific arrester technologies: Gapless Metal-Oxide (MO) Arresters: Defined in IEC 60099-4 .