A utility-scale main substation feeding a 32 MVA industrial campus — dual 69kV service, main-tie-main architecture, and selective coordination across seven protective device tiers.
The project brief: a heavy manufacturing campus with a 32 MVA peak demand, served by dual 69kV utility circuits feeding a main substation built around a main-tie-main transformer architecture. This is a different scale of problem than this studio's sibling program's building-scale industrial-plant project — the subject here is the utility interconnection and main substation feeding an entire campus, not a single building's unit substation, and redundancy engineered at every tier is the dominant design driver throughout.
This module walks the whole project the way a real utility-interconnected industrial design engineer would: a fully worked main substation transformer sizing and N-1 contingency calculation, the eight unit substations and Motor Control Centers that make up the plant's full distribution tier structure, the N+1 emergency generation and NEC 700/702 load segregation, why selective coordination across seven protective device tiers is harder than a single-substation problem, and a worked arc-flash calculation showing how the main-tie-main bus's switching configuration alone — not clearing time — changes the PPE category at the main substation. The full worked numbers, complete bill of materials, and finished design reasoning are part of the unlocked module below.