Designing Structural Supports for High-Voltage Electrical Equipment Using Dynamic Equivalency Models

IEEE 693 when the laboratory support conditions differ from those of the local project.

Dynamic equivalence enables the replication of behavior observed in shake-table testing through calibrated structural models, ensuring that the seismic performance of equipmentsupport assemblies remains consistent across different installation contexts.

The methodology is organized into four stages: data collection, calibration of the structural model, analysis of accelerations and displacements, and final design of the support structure.

Calibration is achieved by adjusting mass distribution and stiffness to reproduce laboratory frequencies and displacements, thereby validating the model against experimental results. Case studies involving a 220 kV voltage transformer, a 500 kV voltage transformer, and a 500 kV surge arrester demonstrate the applicability of the approach, highlighting its ability to capture the dynamic interaction between equipment and support structures.

It is important to clarify that the methodology excludes stress-based design of individual elements and P-Delta/P-δ effects, as these topics are already well established in the technical literature. Such analyses would introduce unnecessary complexity and divert attention from real focus, which is the development of the dynamic equivalence concept.

The results confirm that structural frequencies are significantly higher than equipment frequencies, often by more than an order of magnitude, which enhances displacement control and stability. Increasing support stiffness improves seismic performance, although beyond certain section sizes the benefits diminish while structural weight increases. Additional engineering solutions are explored to achieve a balance between adequate stiffness and optimized weight, ensuring efficiency without compromising safety.

Overall, the proposed methodology strengthens the integration between structural design and seismic performance. By ensuring compatibility of frequencies, accelerations, and displacements, it provides a comprehensive framework for evaluating and improving support structures for high-voltage equipment. The approach not only complies with IEEE 693 requirements but also enhances safety, efficiency, and reliability, while most importantly raising engineering quality and minimizing rework during the detailed design stage.