Find the family.
Then the exact fit.

5–250 MVA common; 13.8–230 kV common, engineered to 400 kV; trailer/skid/container

0.5–50 MVA; 0.4–66 kV; 10/20/40 ft or custom modules

1–500 MVA; 11–420 kV; skid/e-house/preassembled bays; single or multi-module

MV through 1,200 kV; IEC 61850 station/process bus; conventional or non-conventional instrument transformers

5–500+ MVA; collector 11–66 kV to grid 66–500 kV; solar/wind/BESS integration

Roughly 3–45 m/module; LV/MV equipment; single-lift or multi-module; indoor/outdoor/offshore

Roughly 6–45 m/module, 2.5–6 m wide; 0.4–35 kV equipment common, HV interfaces possible

Single panel room through multi-module lineup; LV/MV, arc-resistant and climate-controlled

Small kiosk through large multi-console building; SCADA, telecom, protection and UPS systems

Single-bay kiosk through whole-substation building; dozens to hundreds of panels/IEDs

One feeder/transformer/generator bay through multi-bay panel; 19-inch or full-height cabinet

Small local panel through multi-bay plant/substation lineup; 24–220 Vdc controls and LV auxiliaries

24/48/110/125/220 Vdc; 20–5,000 Ah; lead-acid, Ni-Cd or lithium; 1–24+ hour autonomy

10–1,000 A; 24–220 Vdc; single/three phase; redundant/hot-swap and battery monitoring