# Microgrid mode-dependent earthing interface Canonical URL: https://eloragrid.ai/symbols/microgrid-mode-dependent-earthing-interface Publisher: Elora Grid Updated: 2026-11-03 Lookup label: MMEI Drawing use: Schematic Reference families: Manufacturer Representation: Functional block Installation focus: microgrids Input: Operating mode and earthing states Output: Assigned earthing-system interface Identifies the control and feedback boundary of the selected mode-dependent earthing scheme. ## In plain English ### What this block does Identifies the control and feedback boundary of the selected mode-dependent earthing scheme. ### A simple example In a microgrid with sectionalized buses, the controller can associate each connected source and load group with its current island. A mode-dependent neutral or protection interface needs its own independently validated design. For this reference, the drawing identifies “Operating mode and earthing states” at the input and “Assigned earthing-system interface” at the output. No universal neutral-switching sequence is implied. ### What the drawings help you do Start at the named input: Operating mode and earthing states. Identify its source device or document and the state represented on the drawing. Follow the named output: Assigned earthing-system interface. Cross-reference its destination and separate the command from confirmation that the equipment responded. ### Terms - Input: Operating mode and earthing states - Output: Assigned earthing-system interface - Application reference: An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections. Concept diagram: Operating mode and earthing states → MMEI → Assigned earthing-system interface A reading guide. The entry's original illustration and input/output facts describe this application. - [Microgrid operating modes and transitions management](https://productinfo.se.com/emol_functional_specifications/doca0371_emol_functionalspecifications/EN/DOCA0371_EMOL_Functional_Specifications_DD00894746.xml/%24/EMOL_OperatingModesandTransitionsManagement_DD00895904) ## What it represents Identifies the control and feedback boundary of the selected mode-dependent earthing scheme. Microgrid topology control tracks which sources and load sections are electrically connected. The same physical installation can form several islands, so source roles, measurement boundaries and earthing interfaces must follow the established configuration. In a microgrid with sectionalized buses, the controller can associate each connected source and load group with its current island. A mode-dependent neutral or protection interface needs its own independently validated design. For this reference, the drawing identifies “Operating mode and earthing states” at the input and “Assigned earthing-system interface” at the output. No universal neutral-switching sequence is implied. Keep measured switch positions, logical island assignment and any earthing command separate. A conceptual topology block cannot establish a safe neutral-switching arrangement or prove that a circuit is de-energized. 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: Operating mode and earthing states. Identify its source device or document and the state represented on the drawing. - Follow the named output: Assigned earthing-system interface. Cross-reference its destination and separate the command from confirmation that the equipment responded. - No universal neutral-switching sequence is implied. - Keep measured switch positions, logical island assignment and any earthing command separate. A conceptual topology block cannot establish a safe neutral-switching arrangement or prove that a circuit is de-energized. ## Information to show or reference - Label the source and connection reference for operating mode and earthing states. - Identify the destination and defined state of assigned earthing-system interface. - Record the equipment or control-document revision supporting this functional block. - Check this application limit in the project design: No universal neutral-switching sequence is implied. ## Important distinction No universal neutral-switching sequence is implied. 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: Microgrids - Input / boundary: Operating mode and earthing states - Output / connection: Assigned earthing-system interface - Lookup label: MMEI is a library lookup label, not a standard device designation. ## Public references - [Microgrid operating modes and transitions management](https://productinfo.se.com/emol_functional_specifications/doca0371_emol_functionalspecifications/EN/DOCA0371_EMOL_Functional_Specifications_DD00894746.xml/%24/EMOL_OperatingModesandTransitionsManagement_DD00895904) — Schneider Electric. Public technical context for microgrid topology and earthing coordination. Grid-connected and island modes, transitions, topology and authority. 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.