Definition
A method of connecting the three windings of a three-phase electrical system in a closed loop, where the end of each winding is joined to the start of the next, forming a triangular circuit. In a delta connection, the line voltage equals the phase voltage, while the line current is greater than the phase current by a factor of the square root of three.
Plain English
A way of wiring three coils of a three-phase power system end-to-end so they form a closed triangle. It's one of the two standard ways to connect three-phase electrical equipment on an aircraft, the other being the wye (or star) connection.
Context Anchor
Seen in aircraft electrical system maintenance, especially in discussions of generators, alternators, motors, and transformers that use three-phase power.
Derivation
Named after the Greek capital letter delta (Δ), which is shaped like a triangle. The three windings, when drawn on a schematic, form that same triangular shape — so the name describes the wiring pattern visually.
Why Pilots Care
Maintenance technicians need to recognize delta versus wye wiring when troubleshooting three-phase generators, inverters, and AC motors, because the two configurations behave differently in voltage, current, and fault tolerance.
Analogy
Picture three sides of a triangle. Each side is one winding, and the aircraft’s electrical leads connect at the three corners.
Intuition Check
Delta here does not mean Class D airspace, an airline name, or a change in value. It refers to the triangle-shaped way the electrical windings are connected.
Example Sentence 1
The three-phase generator's output windings are wired in a delta connection, so the line voltage matches the voltage across each individual winding.
Example Sentence 2
Technicians verified that the delta connection remained intact after the generator was removed for inspection.