substations

Substations are facilities in electric power systems where voltage levels are transformed and routed between generation, transmission, and distribution. They connect transmission lines to distribution feeders, change voltages with transformers, and provide switching and protection to control power flow and isolate faults. Substations range from large outdoor installations along transmission corridors to compact pad- or vault-mounted units in urban areas. They may step voltages up for transmission, down for distribution, or serve as switching points that reconfigure networks without changing voltage.

Most substations contain several key components. Transformers adjust voltage; switchgear, including circuit breakers and disconnects, opens and closes circuits under normal and fault conditions; busbars interconnect equipment; protection and control devices such as relays and SCADA monitor status and coordinate operations. Additional devices include capacitor banks and reactors for voltage support and load balancing. Some substations use gas-insulated switchgear (GIS) for compact layouts, while others use air-insulated switchgear. Transmission substations handle higher voltages, while distribution substations step down to typical regional voltages such as 11–33 kV.

Operation and safety: Substations enable reliable power delivery by routing electricity, isolating faults, and allowing maintenance. Protective relays detect abnormal conditions and trigger circuit breakers to interrupt faults. Automation and remote control, often via SCADA, coordinate operations and monitor equipment. Maintenance involves oil management for transformers and safe handling of insulating gases in GIS, along with environmental and safety precautions.