{"schemaVersion":1,"slug":"vt-secondary-fuse-supervision-interface","name":"VT secondary fuse supervision interface","kind":"symbol","abbreviation":"VSFSI","aliases":["Voltage-transformer secondary arrangements","substations Voltage-transformer secondary arrangements","substations","Substations","Voltage fuse supervision","VT-circuit health indication"],"category":"measurement-protection","drawingTypes":["Schematic"],"referenceFamilies":["Manufacturer"],"summary":"Reports the assigned voltage-circuit fuse condition to the protection or alarm system.","description":["Reports the assigned voltage-circuit fuse condition to the protection or alarm system. A voltage-transformer secondary arrangement connects a defined primary voltage measurement to protection, metering or control inputs. Winding identity, fuse protection and the voltage reference must remain visible across the drawing.","In a substation bay, one voltage circuit can feed protection while a separately identified winding supplies metering. A voltage-selection circuit must make clear which bus or line measurement is being used. For this reference, the drawing identifies “Voltage fuse supervision” at the input and “VT-circuit health indication” at the output. Fuse loss must be distinguished from primary undervoltage.","Show the primary measurement point, secondary connection, protective devices and relay reference. A missing measurement can resemble a real system disturbance unless the voltage-circuit health is supervised appropriately. 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: Voltage fuse supervision. Identify its source device or document and the state represented on the drawing.","Follow the named output: VT-circuit health indication. Cross-reference its destination and separate the command from confirmation that the equipment responded.","Fuse loss must be distinguished from primary undervoltage.","Show the primary measurement point, secondary connection, protective devices and relay reference. A missing measurement can resemble a real system disturbance unless the voltage-circuit health is supervised appropriately."],"drawingChecklist":["Label the source and connection reference for voltage fuse supervision.","Identify the destination and defined state of vt-circuit health indication.","Record the equipment or control-document revision supporting this functional block.","Check this application limit in the project design: Fuse loss must be distinguished from primary undervoltage."],"distinction":"Fuse loss must be distinguished from primary undervoltage. 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":"Substations"},{"label":"Input / boundary","value":"Voltage fuse supervision"},{"label":"Output / connection","value":"VT-circuit health indication"},{"label":"Lookup label","value":"VSFSI is a library lookup label, not a standard device designation."}],"references":[{"sourceId":"instrument-transformers","relevance":"Public technical context for voltage-transformer secondary arrangements. Current and voltage measurement transformers and their secondary interfaces. The application text and educational graphic are independently authored; the publisher does not certify this representation."}],"related":["voltage-transformer","potential-test-switch","vt-secondary-mcb-auxiliary-interface"],"artwork":"pi26-vt-secondary-fuse-supervision-interface","publishedOn":"2026-11-03","updatedOn":"2026-11-03","provenance":"independent-public-research","representation":{"type":"functional-block","focus":"substations","family":"vt-secondary","input":"Voltage fuse supervision","output":"VT-circuit health indication"},"plainEnglish":{"title":"What this block does","introduction":"Reports the assigned voltage-circuit fuse condition to the protection or alarm system.","example":"In a substation bay, one voltage circuit can feed protection while a separately identified winding supplies metering. A voltage-selection circuit must make clear which bus or line measurement is being used. For this reference, the drawing identifies “Voltage fuse supervision” at the input and “VT-circuit health indication” at the output. Fuse loss must be distinguished from primary undervoltage.","drawings":"Start at the named input: Voltage fuse supervision. Identify its source device or document and the state represented on the drawing. Follow the named output: VT-circuit health indication. Cross-reference its destination and separate the command from confirmation that the equipment responded.","terms":[{"name":"Input","meaning":"Voltage fuse supervision"},{"name":"Output","meaning":"VT-circuit health indication"},{"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":["Voltage fuse supervision","VSFSI","VT-circuit health indication"],"caption":"A reading guide. The entry's original illustration and input/output facts describe this application.","sources":[{"label":"Indoor current and voltage transformers","url":"https://www.abb.com/gb/en/areas/electrification/medium-voltage/grid-components/core-components/indoor-instrument-transformers"}],"profileId":"power-installation-vt-secondary"},"url":"https://eloragrid.ai/symbols/vt-secondary-fuse-supervision-interface","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/vt-secondary-fuse-supervision-interface.svg","scope":"Original educational concept; not an official standard graphic or product footprint","license":"https://creativecommons.org/licenses/by/4.0/"},"sources":[{"id":"instrument-transformers","title":"Indoor current and voltage transformers","publisher":"ABB","url":"https://www.abb.com/gb/en/areas/electrification/medium-voltage/grid-components/core-components/indoor-instrument-transformers","type":"manufacturer","scope":"Public current- and voltage-transformer product families. Ratings, terminals and dimensions depend on the model.","checkedOn":"2026-10-13","reuse":"link-only","relevance":"Public technical context for voltage-transformer secondary arrangements. Current and voltage measurement transformers and their secondary interfaces. The application text and educational graphic are independently authored; the publisher does not certify this representation."}]}