Similarities and Differences of Chilean Seismic Requirements with IEEE 693-2018

This was the final step in bringing the seismic requirements developed by the CIGRE Chile working group into use as a mandatory standard (previously published as a recommendation).

These seismic requirements were drawn up by Chilean electrical and structural engineers, as well as Chilean seismic experts. They took into account the seismic experience of the Chilean electrical system, the subduction earthquakes (typical in Chile) and the Chilean Regulator's requirement for the facilities: to be available after an earthquake.

On the other hand, there is the IEEE Std 693, “IEEE Recommended Practice for Seismic Design of Substations”, which is a standard used by many manufacturers to supply electrical equipment for use in seismic zones around the world.

Considering that the IEEE standard was developed for crustal earthquakes, which are a different type to subduction earthquakes, there are some seismic requirements that differ from those in the new Chilean standard.

The purpose of this paper is to compare the Chilean Seismic Requirements 2025 with the IEEE

Std 693-2018 & 693a-2024 (References [1] & [2]) for the main requisites such as: requirement response spectrum, soil class, equipment requirements, analysis methods, design methods, simultaneous seismic load cases and requirements for equipment support structures, anchors and foundations, among others. Given also that these new Chilean requirements were developed for the entire facility (not just the electrical equipment as it was the case with the previous requirements), this paper also includes a general analysis of the comments and observations received from electricity transmission companies, consultants, engineering firms, and suppliers during the public consultation phase in June 2024, as well as the current perception using this new standard.