{"schemaVersion":1,"slug":"three-breaker-two-source-transfer-interface","name":"Three-breaker two-source transfer interface","kind":"symbol","abbreviation":"TTTI","aliases":["Switchboard source and bus interfaces","switchgear Switchboard source and bus interfaces","switchgear","Switchgear","Three breaker positions","Transfer arrangement"],"category":"control-circuits","drawingTypes":["Schematic"],"referenceFamilies":["Manufacturer"],"summary":"Relates the two incoming breakers and one bus tie in a defined source-transfer system.","description":["Relates the two incoming breakers and one bus tie in a defined source-transfer system. 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 “Three breaker positions” at the input and “Transfer arrangement” at the output. The interlock matrix determines allowed combinations.","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: Three breaker positions. Identify its source device or document and the state represented on the drawing.","Follow the named output: Transfer arrangement. Cross-reference its destination and separate the command from confirmation that the equipment responded.","The interlock matrix determines allowed combinations.","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 three breaker positions.","Identify the destination and defined state of transfer arrangement.","Record the equipment or control-document revision supporting this functional block.","Check this application limit in the project design: The interlock matrix determines allowed combinations."],"distinction":"The interlock matrix determines allowed combinations. 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":"Three breaker positions"},{"label":"Output / connection","value":"Transfer arrangement"},{"label":"Lookup label","value":"TTTI 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","main-tie-main-source-selection"],"artwork":"pi26-three-breaker-two-source-transfer-interface","publishedOn":"2026-11-03","updatedOn":"2026-11-03","provenance":"independent-public-research","representation":{"type":"functional-block","focus":"switchgear","family":"supply-arrangements","input":"Three breaker positions","output":"Transfer arrangement"},"plainEnglish":{"title":"What this block does","introduction":"Relates the two incoming breakers and one bus tie in a defined source-transfer system.","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 “Three breaker positions” at the input and “Transfer arrangement” at the output. The interlock matrix determines allowed combinations.","drawings":"Start at the named input: Three breaker positions. Identify its source device or document and the state represented on the drawing. Follow the named output: Transfer arrangement. Cross-reference its destination and separate the command from confirmation that the equipment responded.","terms":[{"name":"Input","meaning":"Three breaker positions"},{"name":"Output","meaning":"Transfer arrangement"},{"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":["Three breaker positions","TTTI","Transfer arrangement"],"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/three-breaker-two-source-transfer-interface","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/three-breaker-two-source-transfer-interface.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."}]}