# ANSI/IEEE Star-star-delta three-winding transformer form Canonical URL: https://eloragrid.ai/symbols/ansi-star-star-delta-three-winding-transformer Publisher: Elora Grid Updated: 2026-10-28 Lookup label: TX Y-Y-D Drawing use: SLD, Schematic Reference families: IEEE / ANSI, Manufacturer ## Symbol convention Convention: IEEE / ANSI Form: 3 Phase Star/Star/Delta with 3 Windings Autodesk IEEE Symbol Preview: 3 Phase Transformers, block HXF1T15. Matching functional counterpart linked separately. Independently drawn educational geometry; not a certified IEEE glyph or database identifier. Related representation: [Star-star-delta three-winding transformer](https://eloragrid.ai/symbols/star-star-delta-three-winding-transformer) IEEE-library form of star-star-delta three-winding transformer: a star-star-delta transformer includes two star-connected winding sets and a delta tertiary winding. ## In plain English ### What does ANSI/IEEE Star-star-delta three-winding transformer form mean? This reference locates star-star-delta three-winding transformer in Autodesk's IEEE-oriented 3 phase transformers family. A star-star-delta transformer includes two star-connected winding sets and a delta tertiary winding. The schematic needs all three winding ratings and the intended tertiary connection. The public library uses HXF1T15 for its horizontal representation; this is a vendor block name, not an IEEE standards symbol number. ### A simple example Trace each winding, supply and accessible neutral through the complete machine or transformer connection diagram. Keep the phase arrangement, terminal labels and any clock notation attached to the device; neither the convention label nor this educational outline supplies its ratings. ### What the drawings help you do Trace the tertiary separately so its protection and terminal status remain visible. A delta tertiary is a third winding, not an alternative connection of the main secondary. The linked functional counterpart explains the same operating role in its own drawing context; agreement of every detailed convention mark is not asserted. ### This particular reference IEEE-library form of star-star-delta three-winding transformer: a star-star-delta transformer includes two star-connected winding sets and a delta tertiary winding. A delta tertiary is a third winding, not an alternative connection of the main secondary. ### Terms - Winding: A coil of conductor inside an electrical machine or transformer. - Phase: One of the related AC waveforms in a power system. - Terminal: An identified point where a conductor connects. Concept diagram: Identify the device and form → Read the connections and state → Check the equipment reference A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram. - [Autodesk IEEE Symbol Preview: 3 Phase Transformers](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-EE75A5D4-8CBD-4E78-94A3-226A94E61817.htm) ## What it represents This reference locates star-star-delta three-winding transformer in Autodesk's IEEE-oriented 3 phase transformers family. A star-star-delta transformer includes two star-connected winding sets and a delta tertiary winding. The schematic needs all three winding ratings and the intended tertiary connection. The public library uses HXF1T15 for its horizontal representation; this is a vendor block name, not an IEEE standards symbol number. Trace each winding, supply and accessible neutral through the complete machine or transformer connection diagram. Keep the phase arrangement, terminal labels and any clock notation attached to the device; neither the convention label nor this educational outline supplies its ratings. Trace the tertiary separately so its protection and terminal status remain visible. A delta tertiary is a third winding, not an alternative connection of the main secondary. The linked functional counterpart explains the same operating role in its own drawing context; agreement of every detailed convention mark is not asserted. ## How to read it - Trace the tertiary separately so its protection and terminal status remain visible. - The preview is an original explanation of this function. Match the actual drawing convention to its legend and the selected equipment documentation. ## Information to show or reference - State all three ratings - Show both neutral arrangements - Reference tertiary duty ## Important distinction A delta tertiary is a third winding, not an alternative connection of the main secondary. ## Facts - Convention evidence: Autodesk IEEE Symbol Preview: 3 Phase Transformers; published form: 3 Phase Star/Star/Delta with 3 Windings. - Public vendor block: HXF1T15. Vendor library token, not an IEEE symbol number. - Drawing role: Winding connection - Identifier status: The short label is a functional lookup label, not an assigned IEC or IEEE symbol number. Any separately listed Autodesk code is a verified vendor block name. - Artwork scope: Original educational geometry. Exact standard graphics, product ratings and terminal pinouts are not certified. ## Public references - [Autodesk IEEE Symbol Preview: 3 Phase Transformers](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-EE75A5D4-8CBD-4E78-94A3-226A94E61817.htm) — Autodesk. Public IEEE-oriented 3 Phase Transformers table explicitly lists HXF1T15 as 3 Phase Star/Star/Delta with 3 Windings. This supports the vendor convention context, not reproduction of the publisher graphic. ## Graphic scope Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.