13.8 kV utility substation

Cannot parse line: utility [label: "Grid 138 kV"]

Scenario

A power systems engineer documents a distribution substation design for a utility interconnection application or a facility's electrical permit drawings. The single-line diagram is the first deliverable in any power system project — required by IEEE, NFPA 70E, and utility interconnection standards before detailed engineering begins.

Annotation key

• utility [label: "..."] — utility supply source (three-phase symbol)
• [type: transformer, kva:..., primary:..., secondary:...] — step-down transformer with rated kVA and voltage levels
• [type: bus, voltage:...] — horizontal bus bar at the specified voltage level
• [type: breaker, amps:...] — rated circuit breaker
• [type: load, label:...] — load or feeder destination
• -> — directed power path from source to load

How to read

The 138 kV grid source feeds the high-voltage bus, which connects to the primary of the 15 MVA step-down transformer. The transformer secondary feeds the 13.8 kV medium-voltage bus. Three 1200 A circuit breakers fan out from the MV bus to three distribution feeders — each breaker isolates its feeder independently.