Definition
A coil of wire in a transformer or other electrical device that has an additional electrical connection made at its exact midpoint, dividing the winding into two equal halves. This center connection allows the winding to provide two equal voltages of opposite polarity relative to the tap, or to serve as a common reference point for the circuit.
Plain English
A coil of wire with an extra wire connected to its middle. This middle connection splits the coil into two equal halves, which is useful for getting two matched voltages out of one coil.
Context Anchor
Seen in aircraft electrical system descriptions, especially when discussing coils, transformers, power supplies, and related maintenance checks.
Derivation
The name describes exactly what it is: a winding (a coil of wire wound around a core) with a tap (an extra electrical connection) at its center. 'Tap' in electrical work means a branch-off point where you can draw current from somewhere along a wire's length, not just at the ends.
Why Pilots Care
Center-tapped windings allow balanced positive and negative voltages from a single winding, which some avionics and instrument power supplies require for stable operation.
Analogy
It is like a long extension cord with an extra outlet placed exactly halfway along it. You can use one half, the other half, or the whole length, depending on where you connect.
Intuition Check
“Tapped” does not mean struck or opened like a faucet here. In electrical language, it means an added connection point on a wire or coil.
Example Sentence 1
The transformer's center-tapped winding provided 12 volts on each side of the tap, giving 24 volts across the full coil.
Example Sentence 2
A short on one side of the center-tapped winding can cause the alternator to produce uneven voltage.