{"id":2859,"date":"2026-08-26T05:52:00","date_gmt":"2026-08-26T05:52:00","guid":{"rendered":"https:\/\/lbajiele.com\/?p=2859"},"modified":"2026-08-25T12:09:56","modified_gmt":"2026-08-25T12:09:56","slug":"delta-y-transformer-connection-wiring-and-diagram-guide","status":"publish","type":"post","link":"https:\/\/lbajiele.com\/vi\/blog\/delta-y-transformer-connection-wiring-and-diagram-guide\/","title":{"rendered":"K\u1ebft n\u1ed1i m\u00e1y bi\u1ebfn \u00e1p Sao-Tam gi\u00e1c (Delta-Wye): Nh\u00f3m v\u00e9c-t\u01a1, N\u1ed1i \u0111\u1ea5t &amp; \u1ee8ng d\u1ee5ng"},"content":{"rendered":"<p><strong>A delta-wye transformer connection uses a closed delta on one winding and a grounded or ungrounded wye on the other, creating a 30-degree phase displacement and providing a neutral when the wye point is brought out.<\/strong> The connection is common in three-phase distribution, but the vector group, phase sequence, grounding method, zero-sequence path and protection compensation must be specified together. A simple sketch is not enough for paralleling or relay settings.<\/p>\n<div class=\"lbaji-key-takeaways\"><h2>Nh\u1eefng \u0111i\u1ec3m ch\u00ednh<\/h2><ul><li>Line and phase voltages differ by \u221a3 on the wye side.<\/li><li>Clock notation defines whether the secondary leads or lags and is essential for paralleling.<\/li><li>Grounding and zero-sequence behavior affect faults and protection.<\/li><\/ul><\/div>\n<h2>Delta and Wye Voltage Relationships<\/h2><figure class=\"wp-block-image size-large\"><img decoding=\"async\" alt=\"Delta and star transformer terminal connections\" loading=\"lazy\" src=\"https:\/\/lbajiele.com\/wp-content\/uploads\/2026\/08\/delta-star-terminal-connections.png\"\/><figcaption>Delta and star transformer terminal connections.<\/figcaption><\/figure>\n<p>In delta, each winding phase is connected across a line-to-line voltage, so winding voltage equals line voltage. In wye, each winding phase is connected from line to neutral, so line-to-line voltage equals \u221a3 times phase voltage. Turns ratio must therefore be compared using winding phase voltages, not by dividing two line voltages without considering the connection.<\/p>\n<p>For a 480 V delta to 208Y\/120 V transformer, the delta winding sees 480 V per phase and each wye winding supplies 120 V phase-to-neutral. The secondary line-to-line voltage is approximately 120 \u00d7 \u221a3 = 208 V.<\/p>\n<h2>Thirty-Degree Phase Shift and Vector Groups<\/h2>\n<p>A delta-wye bank introduces a 30-degree displacement between primary and secondary line voltages. Whether the low-voltage side leads or lags depends on terminal polarity and connection. IEC clock notation expresses this relationship, such as Dyn1 or Dyn11, together with the winding connections and accessible neutral.<\/p>\n<p>Transformers intended for parallel operation need compatible ratios, polarity, phase sequence, vector group and impedance. Units with different clock numbers can create severe circulating current or a phase-to-phase short circuit when their secondaries are tied.<\/p>\n<h2>Neutral, Grounding and Zero-Sequence Current<\/h2><figure class=\"wp-block-image size-large\"><img decoding=\"async\" alt=\"Three-phase star and delta winding links\" loading=\"lazy\" src=\"https:\/\/lbajiele.com\/wp-content\/uploads\/2026\/08\/star-delta-transformer-connections.png\"\/><figcaption>Three-phase star and delta winding links.<\/figcaption><\/figure>\n<p>A brought-out wye neutral can supply line-to-neutral loads and can be grounded to establish a system reference. The grounding electrode, neutral conductor, bonding location and separately derived system rules must follow the applicable code and system study. Do not add an unintended second neutral-ground bond downstream.<\/p>\n<p>The delta provides an internal path for triplen harmonics and some zero-sequence current while blocking zero-sequence current from passing as line current to the delta source. This behavior influences ground-fault levels and relay selection.<\/p>\n<h2>Delta-Wye Connection Design Checks<\/h2><figure class=\"wp-block-table is-style-stripes\"><table><thead><tr><th scope=\"col\">Design item<\/th><th scope=\"col\">Delta side<\/th><th scope=\"col\">Wye side<\/th><th scope=\"col\">Why it matters<\/th><\/tr><\/thead><tbody><tr><td>Winding voltage<\/td><td>Equals line voltage<\/td><td>Equals line-to-neutral voltage<\/td><td>Turns ratio calculation<\/td><\/tr><tr><td>Trung l\u1eadp<\/td><td>Not available<\/td><td>Available if brought out<\/td><td>Single-phase loads and grounding<\/td><\/tr><tr><td>\u0110\u1ed9 d\u1ecbch pha<\/td><td>Part of vector group<\/td><td>Shifted 30 degrees<\/td><td>Paralleling and differential protection<\/td><\/tr><tr><td>Zero sequence<\/td><td>Circulates internally<\/td><td>Depends on neutral grounding<\/td><td>Ground-fault current and relays<\/td><\/tr><tr><td>Typical notation<\/td><td>D<\/td><td>y or yn<\/td><td>Defines connection and neutral access<\/td><\/tr><\/tbody><\/table><\/figure>\n<h2>Protection, Testing and Commissioning<\/h2>\n<p>Transformer differential relays must compensate for ratio and 30-degree phase displacement, either in CT connections or numerically. Ground-fault protection should reflect whether the wye neutral is grounded and where CTs are placed. Inrush restraint and overcurrent coordination remain necessary.<\/p>\n<p>Before energization, verify nameplate vector group, terminal markings, phase rotation, ratio on every tap, winding resistance and insulation results. A phase-angle or vector-group test provides stronger evidence than continuity alone.<\/p>\n<h2>X\u00e1c th\u1ef1c k\u1ef9 thu\u1eadt v\u00e0 Gi\u1edbi h\u1ea1n an to\u00e0n<\/h2><p>H\u01b0\u1edbng d\u1eabn n\u00e0y h\u1ed7 tr\u1ee3 vi\u1ec7c l\u1eadp th\u00f4ng s\u1ed1 k\u1ef9 thu\u1eadt v\u00e0 mua s\u1eafm; t\u00e0i li\u1ec7u n\u00e0y kh\u00f4ng thay th\u1ebf cho nghi\u00ean c\u1ee9u d\u1ef1 \u00e1n, quy chu\u1ea9n hi\u1ec7n h\u00e0nh, h\u01b0\u1edbng d\u1eabn c\u1ee7a nh\u00e0 s\u1ea3n xu\u1ea5t ho\u1eb7c c\u00f4ng vi\u1ec7c c\u1ee7a nh\u00e2n vi\u00ean \u0111i\u1ec7n c\u00f3 chuy\u00ean m\u00f4n. H\u00e3y x\u00e1c minh c\u00e1c n\u1ed9i dung sau tr\u01b0\u1edbc khi l\u1ef1a ch\u1ecdn thi\u1ebft b\u1ecb, th\u1eed nghi\u1ec7m, \u0111\u1ea5u d\u00e2y ho\u1eb7c \u0111\u00f3ng \u0111i\u1ec7n:<\/p><ul><li>Confirm terminal polarity, phase sequence and vector group from test records.<\/li><li>Calculate winding voltages before selecting turns ratio or test voltage.<\/li><li>Review grounding and neutral loading, including nonlinear load harmonics.<\/li><li>Coordinate differential and ground-fault protection with the actual connection.<\/li><li>Prohibit paralleling until ratio, angle and impedance compatibility are proven.<\/li><\/ul>\n<h2>Th\u00f4ng tin c\u1ea7n \u0111\u01b0a v\u00e0o Y\u00eau c\u1ea7u b\u00e1o gi\u00e1<\/h2><p>M\u1ed9t b\u00e1o gi\u00e1 h\u1eefu \u00edch ph\u1ea3i d\u1ef1a tr\u00ean c\u00f9ng m\u1ed9t ranh gi\u1edbi k\u1ef9 thu\u1eadt cho m\u1ecdi nh\u00e0 cung c\u1ea5p. H\u00e3y bao g\u1ed3m c\u00e1c th\u00f4ng tin sau v\u00e0 y\u00eau c\u1ea7u li\u1ec7t k\u00ea r\u00f5 r\u00e0ng m\u1ecdi sai l\u1ec7ch:<\/p><ul><li>Primary and secondary line voltages, kVA, frequency and tap range.<\/li><li>Required vector group and whether the wye neutral is brought out.<\/li><li>Grounding method, neutral current and load unbalance.<\/li><li>Impedance, fault level and parallel-operation requirements.<\/li><li>Terminal diagram, phase-angle test report and protection interface data.<\/li><\/ul>\n<h2>T\u1eeb D\u1eef li\u1ec7u K\u1ef9 thu\u1eadt \u0111\u1ebfn m\u1ed9t Quy\u1ebft \u0111\u1ecbnh \u0111\u01b0\u1ee3c Ph\u00ea duy\u1ec7t<\/h2><p>Use a staged review rather than approving the first catalogue match. Begin with delta and wye voltage relationships, then reconcile thirty-degree phase shift and vector groups with neutral, grounding and zero-sequence current. Complete the review with protection, testing and commissioning. At each stage, record the source document, units, operating case and person responsible for approval. This prevents a value copied from an old drawing, nominal system label or unrelated product from becoming an uncontrolled design input.<\/p><p>Tr\u01b0\u1edbc khi nghi\u1ec7m thu, h\u00e3y so s\u00e1nh ph\u1ea3n h\u1ed3i c\u1ee7a nh\u00e0 th\u1ea7u t\u1eebng d\u00f2ng m\u1ed9t v\u1edbi Y\u00eau c\u1ea7u b\u00e1o gi\u00e1 (RFQ) v\u00e0 \u0111\u00e1nh d\u1ea5u m\u1ecdi \u0111i\u1ec3m ngo\u1ea1i l\u1ec7. X\u00e1c nh\u1eadn r\u1eb1ng c\u00e1c b\u1ea3n v\u1ebd, t\u00ednh to\u00e1n, th\u00f4ng s\u1ed1 c\u00e0i \u0111\u1eb7t, ch\u1ee9ng ch\u1ec9 v\u00e0 b\u00e1o c\u00e1o th\u1eed nghi\u1ec7m \u0111\u1ec1u \u0111\u1ec1 c\u1eadp ch\u00ednh x\u00e1c \u0111\u1ebfn m\u1eabu v\u00e0 phi\u00ean b\u1ea3n \u0111\u01b0\u1ee3c ch\u00e0o th\u1ea7u. L\u01b0u gi\u1eef h\u1ed3 s\u01a1 tr\u00ecnh duy\u1ec7t \u0111\u00e3 \u0111\u01b0\u1ee3c ph\u00ea duy\u1ec7t, d\u1eef li\u1ec7u tr\u00ean nh\u00e3n thi\u1ebft b\u1ecb, k\u1ebft qu\u1ea3 th\u1eed nghi\u1ec7m t\u1ea1i x\u01b0\u1edfng v\u00e0 c\u00e1c th\u00f4ng s\u1ed1 \u0111o \u0111\u1ea1c khi ch\u1ea1y th\u1eed l\u00e0m c\u01a1 s\u1edf b\u1ea3o tr\u00ec. N\u1ebfu c\u00f3 s\u1ef1 thay \u0111\u1ed5i v\u1ec1 \u0111\u1ecbnh m\u1ee9c, k\u1ebft n\u1ed1i, m\u00f4i tr\u01b0\u1eddng ho\u1eb7c \u0111i\u1ec1u ki\u1ec7n th\u1eed nghi\u1ec7m, h\u00e3y l\u1eb7p l\u1ea1i vi\u1ec7c \u0111\u00e1nh gi\u00e1 \u0111\u1ed1i v\u1edbi ph\u1ea7n b\u1ecb \u1ea3nh h\u01b0\u1edfng thay v\u00ec gi\u1ea3 \u0111\u1ecbnh r\u1eb1ng k\u1ebft lu\u1eadn ban \u0111\u1ea7u v\u1eabn c\u00f2n gi\u00e1 tr\u1ecb.<\/p>\n<p>Vi\u1ec7c ki\u1ec3m so\u00e1t t\u00e0i li\u1ec7u ph\u1ea3i x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1ee3c phi\u00ean b\u1ea3n, tr\u1ea1ng th\u00e1i ph\u00ea duy\u1ec7t v\u00e0 c\u00e1c t\u1ec7p b\u1ecb thay th\u1ebf. C\u00e1c \u0111\u1ed9i ng\u0169 hi\u1ec7n tr\u01b0\u1eddng ph\u1ea3i nh\u1eadn \u0111\u01b0\u1ee3c c\u00e1c gi\u00e1 tr\u1ecb \u0111\u00e3 \u0111\u01b0\u1ee3c ph\u00ea duy\u1ec7t gi\u1ed1ng nhau \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng cho vi\u1ec7c mua s\u1eafm, trong khi c\u00e1c h\u1ed3 s\u01a1 ch\u1ea1y th\u1eed ph\u1ea3i ghi l\u1ea1i m\u1ecdi thay \u0111\u1ed5i \u0111\u01b0\u1ee3c \u1ee7y quy\u1ec1n th\u1ef1c hi\u1ec7n trong qu\u00e1 tr\u00ecnh l\u1eafp \u0111\u1eb7t. Kh\u1ea3 n\u0103ng truy xu\u1ea5t ngu\u1ed3n g\u1ed1c n\u00e0y \u0111\u1eb7c bi\u1ec7t quan tr\u1ecdng khi thi\u1ebft b\u1ecb \u0111\u01b0\u1ee3c thay th\u1ebf nhi\u1ec1u n\u0103m sau \u0111\u00f3: k\u1ef9 s\u01b0 ti\u1ebfp theo c\u1ea7n c\u00e1c giao di\u1ec7n \u0111\u00e3 \u0111\u01b0\u1ee3c x\u00e1c minh v\u00e0 l\u1ecbch s\u1eed ki\u1ec3m tra, ch\u1ee9 kh\u00f4ng ph\u1ea3i l\u00e0 m\u1ed9t m\u00f4 t\u1ea3 ch\u01b0a \u0111\u1ea7y \u0111\u1ee7 \u0111\u01b0\u1ee3c sao ch\u00e9p t\u1eeb \u0111\u01a1n \u0111\u1eb7t h\u00e0ng.<\/p>\n<h2>Th\u00f4ng tin bao qu\u00e1t d\u1ef1a tr\u00ean k\u1ebft qu\u1ea3 t\u00ecm ki\u1ebfm hi\u1ec7n t\u1ea1i<\/h2><p>The current U.S. Google top-20 review repeatedly surfaced themes including Wye (Y) Connection, Delta (\u0394) Connection, Wye-Wye (Y-Y), I have two Delta Wye transformers installed in a main-tie-main. One failed, can I replace the failed one with a Wye Wye?, What Are the Differences Between Delta and WYE Systems?. The article addresses those user needs in an original engineering and procurement sequence; competitor brand navigation and unrelated sales material were excluded.<\/p>\n<h2>T\u00e0i li\u1ec7u LBAJI li\u00ean quan<\/h2><p>Ti\u1ebfp t\u1ee5c v\u1edbi <a href=\"https:\/\/lbajiele.com\/vi\/blog\/complete-guide-to-transformer-voltage-connections-vector-groups\/\">transformer voltage and vector-group guide<\/a> <a href=\"https:\/\/lbajiele.com\/vi\/blog\/transformer-wiring-diagram-wiring-and-diagram-guide\/\">transformer wiring diagram guide<\/a> <a href=\"https:\/\/lbajiele.com\/vi\/danh-muc-san-pham\/transformer\/\">three-phase transformer products<\/a>. Nh\u1eefng t\u00e0i nguy\u00ean n\u00e0y gi\u00fap k\u1ebft n\u1ed1i vi\u1ec7c t\u00ednh to\u00e1n ho\u1eb7c quy\u1ebft \u0111\u1ecbnh l\u1ef1a ch\u1ecdn linh ki\u1ec7n v\u1edbi m\u1ed9t b\u1ea3ng th\u00f4ng s\u1ed1 k\u1ef9 thu\u1eadt ho\u00e0n ch\u1ec9nh c\u1ee7a m\u00e1y bi\u1ebfn \u00e1p, thi\u1ebft b\u1ecb \u0111\u00f3ng c\u1eaft, thi\u1ebft b\u1ecb \u0111i\u1ec1u khi\u1ec3n ho\u1eb7c thi\u1ebft b\u1ecb ph\u00e2n ph\u1ed1i.<\/p>\n<div id=\"rank-math-faq\" class=\"rank-math-block\">\n<div class=\"rank-math-list\">\n<\/div>\n<\/div>\n<section class=\"lbaji-technical-references\"><h2>T\u00e0i li\u1ec7u tham kh\u1ea3o k\u1ef9 thu\u1eadt v\u00e0 \u0110\u1ecdc th\u00eam<\/h2><ul><li><a href=\"https:\/\/webstore.iec.ch\/en\/publication\/588\" rel=\"noopener noreferrer nofollow\" target=\"_blank\">M\u00e1y bi\u1ebfn \u00e1p \u0111i\u1ec7n l\u1ef1c IEC 60076-1<\/a> \u2014 Connection symbols and transformer requirements.<\/li><li><a href=\"https:\/\/standards.ieee.org\/\" rel=\"noopener noreferrer nofollow\" target=\"_blank\">IEEE Standards Association transformer standards<\/a> \u2014 Transformer connection, testing and protection standards.<\/li><li><a href=\"https:\/\/www.nfpa.org\/codes-and-standards\" rel=\"noopener noreferrer nofollow\" target=\"_blank\">C\u00e1c quy chu\u1ea9n v\u00e0 ti\u00eau chu\u1ea9n NFPA<\/a> \u2014 Electrical grounding and installation requirements.<\/li><\/ul><\/section>\n<h2>K\u1ebft lu\u1eadn<\/h2><p>A delta-wye connection should be specified by vector group, not merely by the words delta and wye. Correct phase-angle, neutral grounding, zero-sequence and protection decisions are required before wiring, testing or paralleling.<\/p>","protected":false},"excerpt":{"rendered":"<p>K\u1ebft n\u1ed1i m\u00e1y bi\u1ebfn \u00e1p tam gi\u00e1c-sao s\u1eed d\u1ee5ng m\u1ed9t m\u1ea1ch tam gi\u00e1c k\u00edn \u1edf m\u1ed9t cu\u1ed9n d\u00e2y v\u00e0 m\u1ed9t \u0111\u1ea5u sao c\u00f3 n\u1ed1i \u0111\u1ea5t ho\u1eb7c kh\u00f4ng n\u1ed1i \u0111\u1ea5t \u1edf cu\u1ed9n d\u00e2y kia, t\u1ea1o ra \u0111\u1ed9 l\u1ec7ch pha 30 \u0111\u1ed9 v\u00e0 cung c\u1ea5p m\u1ed9t \u0111i\u1ec3m trung t\u00ednh khi \u0111\u1ea7u n\u1ed1i sao \u0111\u01b0\u1ee3c \u0111\u01b0a ra ngo\u00e0i.<\/p>","protected":false},"author":6,"featured_media":2858,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[52],"tags":[64,73],"class_list":["post-2859","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-transformers","tag-three-phase-transformer","tag-transformer-connections"],"blocksy_meta":[],"acf":[],"_links":{"self":[{"href":"https:\/\/lbajiele.com\/vi\/wp-json\/wp\/v2\/posts\/2859","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lbajiele.com\/vi\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/lbajiele.com\/vi\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/lbajiele.com\/vi\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/lbajiele.com\/vi\/wp-json\/wp\/v2\/comments?post=2859"}],"version-history":[{"count":1,"href":"https:\/\/lbajiele.com\/vi\/wp-json\/wp\/v2\/posts\/2859\/revisions"}],"predecessor-version":[{"id":3007,"href":"https:\/\/lbajiele.com\/vi\/wp-json\/wp\/v2\/posts\/2859\/revisions\/3007"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/lbajiele.com\/vi\/wp-json\/wp\/v2\/media\/2858"}],"wp:attachment":[{"href":"https:\/\/lbajiele.com\/vi\/wp-json\/wp\/v2\/media?parent=2859"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/lbajiele.com\/vi\/wp-json\/wp\/v2\/categories?post=2859"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lbajiele.com\/vi\/wp-json\/wp\/v2\/tags?post=2859"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}