Underground Cable (Transmission)

A transmission conductor buried beneath the earth's surface within an insulated cable system — typically XLPE (cross-linked polyethylene) or fluid-filled paper insulation — used where overhead lines are impractical due to urban density, water crossings, environmental constraints, or aesthetic requirements. Underground cables have dramatically higher capacitance per unit length than overhead lines (10–20×), generating large amounts of reactive charging current that limits practical AC cable length to typically 50–100 km without reactive compensation. For long underground links (harbor crossings, offshore wind connections), HVDC cable technology avoids the reactive power limitation of AC cables.

Ready to test yourself?

Practice this term with interactive flashcards

Explore more

All games · Transmission Planner · Docket Defender · Energy Persona quiz