{"schemaVersion":1,"slug":"source-availability-selection-interface","name":"Source-availability selection interface","kind":"symbol","abbreviation":"SSI","aliases":["Switchboard source and bus interfaces","switchgear Switchboard source and bus interfaces","switchgear","Switchgear","Incoming source health","Available-source selection"],"category":"control-circuits","drawingTypes":["Schematic"],"referenceFamilies":["Manufacturer"],"summary":"Compares the declared health of available incoming sources for transfer logic.","description":["Compares the declared health of available incoming sources for transfer logic. 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 “Incoming source health” at the input and “Available-source selection” at the output. Source voltage alone may not establish supply suitability.","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: Incoming source health. Identify its source device or document and the state represented on the drawing.","Follow the named output: Available-source selection. Cross-reference its destination and separate the command from confirmation that the equipment responded.","Source voltage alone may not establish supply suitability.","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 incoming source health.","Identify the destination and defined state of available-source selection.","Record the equipment or control-document revision supporting this functional block.","Check this application limit in the project design: Source voltage alone may not establish supply suitability."],"distinction":"Source voltage alone may not establish supply suitability. 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":"Incoming source health"},{"label":"Output / connection","value":"Available-source selection"},{"label":"Lookup label","value":"SSI 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","incomer-transfer-in-progress-indication"],"artwork":"pi26-source-availability-selection-interface","publishedOn":"2026-11-03","updatedOn":"2026-11-03","provenance":"independent-public-research","representation":{"type":"functional-block","focus":"switchgear","family":"supply-arrangements","input":"Incoming source health","output":"Available-source selection"},"plainEnglish":{"title":"What this block does","introduction":"Compares the declared health of available incoming sources for transfer logic.","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 “Incoming source health” at the input and “Available-source selection” at the output. Source voltage alone may not establish supply suitability.","drawings":"Start at the named input: Incoming source health. Identify its source device or document and the state represented on the drawing. Follow the named output: Available-source selection. Cross-reference its destination and separate the command from confirmation that the equipment responded.","terms":[{"name":"Input","meaning":"Incoming source health"},{"name":"Output","meaning":"Available-source selection"},{"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":["Incoming source health","SSI","Available-source selection"],"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/source-availability-selection-interface","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/source-availability-selection-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."}]}