Addressed structurally in Annex J to assist utilities maintaining older grid infrastructure.
You can find the IEC 60099-5 standard document on various websites, including:
) into the varistor blocks during lightning and line-switching actions. The selected device must possess a thermal rating ( Qthcap Q sub t h end-sub ) that safely exceeds this estimated energy load. 5. Calculating Protective Margins
Surge arresters safeguard transformers and switchgear from fast-acting overvoltages. The non-linear behavior of Metal-Oxide Varistors (MOVs) transitions them from insulators to conductors instantly when voltage spikes occur. A classic voltage-current (
: The dominant technology deployed in modern substations, adhering fundamentally to IEC 60099-4.
Here’s a draft post for requesting or referencing the PDF (note: the correct standard number is IEC 60099 , not 600995 — likely a typo). I’ve included versions for different contexts.