Short Answer:

Substations are classified based on their function, construction, and voltage level. The major types include transmission substations, distribution substations, switching substations, and converter substations. Each serves a specific purpose in the power system to step up, step down, or redirect electrical power.

Substations can also be categorized as indoor, outdoor, underground, pole-mounted, or gas-insulated (GIS) depending on space, environment, and safety needs. Choosing the right substation type depends on factors like location, load, voltage, and system requirements.

Detailed Explanation:

Types of substations

Substations are critical parts of the power system where electrical energy is transformed, distributed, or controlled. Based on various criteria, the types include:

1. Based on function:
   • Transmission substation: Steps up voltage for long-distance transmission.
   • Distribution substation: Steps down voltage for local supply.
   • Switching substation: Only switches power without voltage change.
   • Converter substation: Converts AC to DC or vice versa (used in HVDC systems).
2. Based on construction:
   • Outdoor substation: Equipment is installed outside; used where land is available.
   • Indoor substation: Installed inside buildings; used in urban or high-risk areas.
   • Underground substation: Found in cities to save space.
   • Pole-mounted substation: Small capacity substations mounted on poles, common in rural areas.
3. Based on insulation:
   • Air-insulated substation (AIS): Uses air for insulation.
   • Gas-insulated substation (GIS): Uses SF₆ gas; compact and suitable for urban use.

Conclusion:

Substations are categorized into various types based on function, construction, and insulation. These include transmission, distribution, switching, and converter substations, as well as outdoor, indoor, and gas-insulated designs. Each type serves a specific role in the safe and efficient operation of power systems.