# Dead-bus close permission Canonical URL: https://eloragrid.ai/symbols/dead-bus-close-permission Publisher: Elora Grid Updated: 2026-11-03 Lookup label: DCP Drawing use: Schematic Reference families: Manufacturer Representation: Functional block Installation focus: switchgear Input: Bus voltage and source status Output: Dead-bus closing permission Allows the documented source to energize a bus established as dead by its voltage checks. ## In plain English ### What this block does Allows the documented source to energize a bus established as dead by its voltage checks. ### A simple example In a switchgear bus-coupler panel, a close request is checked against position, mechanism readiness and the selected live-bus or dead-bus conditions before the closing circuit is enabled. For this reference, the drawing identifies “Bus voltage and source status” at the input and “Dead-bus closing permission” at the output. Loss of voltage sensing is not proof of a dead bus. ### What the drawings help you do Start at the named input: Bus voltage and source status. Identify its source device or document and the state represented on the drawing. Follow the named output: Dead-bus closing permission. Cross-reference its destination and separate the command from confirmation that the equipment responded. ### Terms - Input: Bus voltage and source status - Output: Dead-bus closing permission - Application reference: An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections. Concept diagram: Bus voltage and source status → DCP → Dead-bus closing permission A reading guide. The entry's original illustration and input/output facts describe this application. - [Masterclad medium-voltage switchgear: circuit-breaker section interlocks](https://productinfo.se.com/masterclad_mv_switchgear_ib/6055-30-masterclad-15kv-mv-switchgear-ib/English/6055-30%20Masterclad%20MV%20Switchgear%20Indoor%20%28bookmap%29_DD00646805.xml/%24/Section6-CircuitBreakerSectionInter-58DD6EC7) ## What it represents Allows the documented source to energize a bus established as dead by its voltage checks. A closing circuit combines an operator or automatic request with the conditions that allow the breaker to close. The closing coil releases stored mechanism energy where that construction is used; it is different from the spring-charging motor. In a switchgear bus-coupler panel, a close request is checked against position, mechanism readiness and the selected live-bus or dead-bus conditions before the closing circuit is enabled. For this reference, the drawing identifies “Bus voltage and source status” at the input and “Dead-bus closing permission” at the output. Loss of voltage sensing is not proof of a dead bus. Follow request, permission and final coil output as separate signals. A permissive diagram must say which conditions block closing and what happens if a feedback signal becomes unavailable. 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. ## How to read it - Start at the named input: Bus voltage and source status. Identify its source device or document and the state represented on the drawing. - Follow the named output: Dead-bus closing permission. Cross-reference its destination and separate the command from confirmation that the equipment responded. - Loss of voltage sensing is not proof of a dead bus. - Follow request, permission and final coil output as separate signals. A permissive diagram must say which conditions block closing and what happens if a feedback signal becomes unavailable. ## Information to show or reference - Label the source and connection reference for bus voltage and source status. - Identify the destination and defined state of dead-bus closing permission. - Record the equipment or control-document revision supporting this functional block. - Check this application limit in the project design: Loss of voltage sensing is not proof of a dead bus. ## Important distinction Loss of voltage sensing is not proof of a dead bus. 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 - Representation: Functional block - Installation focus: Switchgear - Input / boundary: Bus voltage and source status - Output / connection: Dead-bus closing permission - Lookup label: DCP is a library lookup label, not a standard device designation. ## Public references - [Masterclad medium-voltage switchgear: circuit-breaker section interlocks](https://productinfo.se.com/masterclad_mv_switchgear_ib/6055-30-masterclad-15kv-mv-switchgear-ib/English/6055-30%20Masterclad%20MV%20Switchgear%20Indoor%20%28bookmap%29_DD00646805.xml/%24/Section6-CircuitBreakerSectionInter-58DD6EC7) — Schneider Electric. Public technical context for breaker closing controls. Breaker control, mechanism, position contacts, racking interlocks and test interfaces. The application text and educational graphic are independently authored; the publisher does not certify this representation. ## Graphic scope Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.