Compact substation boxes, with advantages like safe operation, high reliability, and easy maintenance, are used in urban grid construction/renovation. Structurally divided into American - style (high - cost, noisy, low - efficiency, gradually phased out) and European - style (large - sized but more advantages, still popular).To address their pros/cons, ring - network prefabricated ones were developed.I. Basic Materials for Prefabricated Compact Substation BoxesMaterials need hardness, strength,