{"schemaVersion":1,"slug":"transformer-tap-changer-oil-level-alarm","name":"Transformer tap-changer oil-level alarm","kind":"symbol","abbreviation":"TTOA","aliases":["Transformer protection and monitoring interfaces","substations Transformer protection and monitoring interfaces","substations","Substations","Tap-changer level contact","Tap-changer level alarm"],"category":"measurement-protection","drawingTypes":["Schematic"],"referenceFamilies":["Manufacturer"],"summary":"Separates the tap-changer oil-system level indication from the transformer main-tank indication.","description":["Separates the tap-changer oil-system level indication from the transformer main-tank indication. Transformer monitoring interfaces connect physical sensors and protection calculations to the station's alarms and trip logic. Temperature, oil, gas, pressure and electrical measurements indicate different conditions and require separate interpretation.","In a substation transformer bay, a protection panel receives winding-current measurements and equipment alarm contacts. An operator can then distinguish an electrical protection operation from a cooling-system or physical-condition alarm. For this reference, the drawing identifies “Tap-changer level contact” at the input and “Tap-changer level alarm” at the output. Oil compartments may have separate sensors.","Identify the sensor or calculation, its monitored zone and its assigned response. Alarm and trip thresholds, sensor fitting and protection settings belong to the selected transformer documentation and the approved protection design. 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: Tap-changer level contact. Identify its source device or document and the state represented on the drawing.","Follow the named output: Tap-changer level alarm. Cross-reference its destination and separate the command from confirmation that the equipment responded.","Oil compartments may have separate sensors.","Identify the sensor or calculation, its monitored zone and its assigned response. Alarm and trip thresholds, sensor fitting and protection settings belong to the selected transformer documentation and the approved protection design."],"drawingChecklist":["Label the source and connection reference for tap-changer level contact.","Identify the destination and defined state of tap-changer level alarm.","Record the equipment or control-document revision supporting this functional block.","Check this application limit in the project design: Oil compartments may have separate sensors."],"distinction":"Oil compartments may have separate sensors. 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":"Tap-changer level contact"},{"label":"Output / connection","value":"Tap-changer level alarm"},{"label":"Lookup label","value":"TTOA is a library lookup label, not a standard device designation."}],"references":[{"sourceId":"pi26-transformer-relay","relevance":"Public technical context for transformer protection and monitoring interfaces. Transformer protection, monitoring and measurement interfaces. The application text and educational graphic are independently authored; the publisher does not certify this representation."}],"related":["power-transformer","87t-transformer-differential-protection","transformer-top-oil-temperature-alarm-interface"],"artwork":"pi26-transformer-tap-changer-oil-level-alarm","publishedOn":"2026-11-03","updatedOn":"2026-11-03","provenance":"independent-public-research","representation":{"type":"functional-block","focus":"substations","family":"transformer-monitoring","input":"Tap-changer level contact","output":"Tap-changer level alarm"},"plainEnglish":{"title":"What this block does","introduction":"Separates the tap-changer oil-system level indication from the transformer main-tank indication.","example":"In a substation transformer bay, a protection panel receives winding-current measurements and equipment alarm contacts. An operator can then distinguish an electrical protection operation from a cooling-system or physical-condition alarm. For this reference, the drawing identifies “Tap-changer level contact” at the input and “Tap-changer level alarm” at the output. Oil compartments may have separate sensors.","drawings":"Start at the named input: Tap-changer level contact. Identify its source device or document and the state represented on the drawing. Follow the named output: Tap-changer level alarm. Cross-reference its destination and separate the command from confirmation that the equipment responded.","terms":[{"name":"Input","meaning":"Tap-changer level contact"},{"name":"Output","meaning":"Tap-changer level alarm"},{"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":["Tap-changer level contact","TTOA","Tap-changer level alarm"],"caption":"A reading guide. The entry's original illustration and input/output facts describe this application.","sources":[{"label":"SEL-487E transformer protection relay","url":"https://selinc.com/products/487E/"}],"profileId":"power-installation-transformer-monitoring"},"url":"https://eloragrid.ai/symbols/transformer-tap-changer-oil-level-alarm","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/transformer-tap-changer-oil-level-alarm.svg","scope":"Original educational concept; not an official standard graphic or product footprint","license":"https://creativecommons.org/licenses/by/4.0/"},"sources":[{"id":"pi26-transformer-relay","publisher":"SEL","title":"SEL-487E transformer protection relay","url":"https://selinc.com/products/487E/","scope":"Transformer protection, monitoring and measurement interfaces.","type":"manufacturer","checkedOn":"2026-11-03","reuse":"link-only","relevance":"Public technical context for transformer protection and monitoring interfaces. Transformer protection, monitoring and measurement interfaces. The application text and educational graphic are independently authored; the publisher does not certify this representation."}]}