Editing Transformer (section)

===Polarity===
A [[dot convention]] is often used in transformer circuit diagrams, nameplates or terminal markings to define the relative polarity of transformer windings. Positively increasing instantaneous current entering the primary winding's 'dot' end induces positive polarity voltage exiting the secondary winding's 'dot' end. Three-phase transformers used in electric power systems will have a nameplate that indicate the phase relationships between their terminals. This may be in the form of a [[phasor]] diagram, or using an alpha-numeric code to show the type of internal connection (wye or delta) for each winding.