{"schemaVersion":1,"slug":"dual-incomer-normally-open-bus-tie","name":"Dual-incomer normally-open bus tie","kind":"symbol","abbreviation":"DNBT","aliases":["Switchboard source and bus interfaces","switchgear Switchboard source and bus interfaces","switchgear","Switchgear","Two incoming supplies","Separated operating sections"],"category":"control-circuits","drawingTypes":["Schematic"],"referenceFamilies":["Manufacturer"],"summary":"Shows two source-fed sections separated by a tie that is normally open.","description":["Shows two source-fed sections separated by a tie that is normally open. A source and bus arrangement shows how incoming supplies and outgoing circuits can be connected. Breaker and tie positions determine which sections are energized and whether sources can become electrically paralleled.","In a switchgear lineup with two incomers and a bus tie, the single-line arrangement helps the engineer identify normal supply paths and which loads change source during a transfer. For this reference, the drawing identifies “Two incoming supplies” at the input and “Separated operating sections” at the output. Tie closing can create a source-parallel condition.","Keep normal positions, transfer limits, source independence and protection-zone boundaries visible. An arrangement drawing explains connectivity; the permitted switching sequence needs a separate approved scheme. The functional block is an independent explanation of this named application. Equipment-specific ratings, terminal connections and operating conditions must be established in the project documentation."],"readingNotes":["Start at the named input: Two incoming supplies. Identify its source device or document and the state represented on the drawing.","Follow the named output: Separated operating sections. Cross-reference its destination and separate the command from confirmation that the equipment responded.","Tie closing can create a source-parallel condition.","Keep normal positions, transfer limits, source independence and protection-zone boundaries visible. An arrangement drawing explains connectivity; the permitted switching sequence needs a separate approved scheme."],"drawingChecklist":["Label the source and connection reference for two incoming supplies.","Identify the destination and defined state of separated operating sections.","Record the equipment or control-document revision supporting this functional block.","Check this application limit in the project design: Tie closing can create a source-parallel condition."],"distinction":"Tie closing can create a source-parallel condition. This reference describes the named application; it does not establish a new IEC graphical symbol, an ANSI device-function number or an exact manufacturer connection diagram.","facts":[{"label":"Representation","value":"Functional block"},{"label":"Installation focus","value":"Switchgear"},{"label":"Input / boundary","value":"Two incoming supplies"},{"label":"Output / connection","value":"Separated operating sections"},{"label":"Lookup label","value":"DNBT is a library lookup label, not a standard device designation."}],"references":[{"sourceId":"pi26-bus-schemes","relevance":"Public technical context for switchboard source and bus interfaces. Bus arrangements, breaker control and bay-level coordination. The application text and educational graphic are independently authored; the publisher does not certify this representation."}],"related":["busbar","automatic-transfer-switch","dual-incomer-normally-closed-bus-tie"],"artwork":"pi26-dual-incomer-normally-open-bus-tie","publishedOn":"2026-11-03","updatedOn":"2026-11-03","provenance":"independent-public-research","representation":{"type":"functional-block","focus":"switchgear","family":"supply-arrangements","input":"Two incoming supplies","output":"Separated operating sections"},"plainEnglish":{"title":"What this block does","introduction":"Shows two source-fed sections separated by a tie that is normally open.","example":"In a switchgear lineup with two incomers and a bus tie, the single-line arrangement helps the engineer identify normal supply paths and which loads change source during a transfer. For this reference, the drawing identifies “Two incoming supplies” at the input and “Separated operating sections” at the output. Tie closing can create a source-parallel condition.","drawings":"Start at the named input: Two incoming supplies. Identify its source device or document and the state represented on the drawing. Follow the named output: Separated operating sections. Cross-reference its destination and separate the command from confirmation that the equipment responded.","terms":[{"name":"Input","meaning":"Two incoming supplies"},{"name":"Output","meaning":"Separated operating sections"},{"name":"Application reference","meaning":"An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections."}],"diagram":"flow","steps":["Two incoming supplies","DNBT","Separated operating sections"],"caption":"A reading guide. The entry's original illustration and input/output facts describe this application.","sources":[{"label":"SEL-451 protection, automation and bay control","url":"https://selinc.com/products/451/"}],"profileId":"power-installation-supply-arrangements"},"url":"https://eloragrid.ai/symbols/dual-incomer-normally-open-bus-tie","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/dual-incomer-normally-open-bus-tie.svg","scope":"Original educational concept; not an official standard graphic or product footprint","license":"https://creativecommons.org/licenses/by/4.0/"},"sources":[{"id":"pi26-bus-schemes","publisher":"SEL","title":"SEL-451 protection, automation and bay control","url":"https://selinc.com/products/451/","scope":"Bus arrangements, breaker control and bay-level coordination.","type":"manufacturer","checkedOn":"2026-11-03","reuse":"link-only","relevance":"Public technical context for switchboard source and bus interfaces. Bus arrangements, breaker control and bay-level coordination. The application text and educational graphic are independently authored; the publisher does not certify this representation."}]}