Definition
A method of wiring a three-phase electrical system in which the three windings or components are connected end-to-end in a closed triangular loop, with the external supply lines attached at the three corners. In a delta connection, the line voltage equals the voltage across each winding, while the line current is greater than the current in each winding.
Plain English
A way of joining the three coils of a three-phase generator or motor into a triangle shape, with the wires that carry power to the rest of the system attached at the three corners of the triangle.
Context Anchor
Seen in aircraft electrical system maintenance when discussing three-phase generators, alternators, motors, or transformer wiring.
Derivation
Named after the Greek capital letter delta (Δ), which is shaped like a triangle. The three windings, drawn on a schematic, form that same triangle shape — so the wiring layout takes the letter's name.
Why Pilots Care
Three-phase aircraft generators and motors are wired in either delta or wye (star) configurations. Knowing which one you are looking at tells a technician how voltage and current behave in the circuit, which matters when troubleshooting electrical faults or interpreting wiring diagrams.
Analogy
Picture three identical batteries or coils connected in a triangle, with a wire coming off each corner. The triangle shape is the key idea behind a delta connection.
Intuition Check
Delta does not mean a change or an airport control area here. In this term, delta means a triangle-shaped electrical connection.
Example Sentence 1
The aircraft's three-phase AC generator uses a delta connection, with each winding forming one side of the triangle.
Example Sentence 2
A loose terminal in the delta connection caused unbalanced voltage on the main bus.