# Microgrid dead-island utility-reconnect interface

Canonical URL: https://eloragrid.ai/symbols/microgrid-dead-island-utility-reconnect-interface
Publisher: Elora Grid
Updated: 2026-11-03
Lookup label: MDUI
Drawing use: Schematic
Reference families: Manufacturer

Representation: Functional block
Installation focus: microgrids
Input: Utility and island voltage conditions
Output: Assigned reconnect case

Distinguishes the documented dead-island energization case from live-island synchronised reconnection.

## In plain English

### What this block does

Distinguishes the documented dead-island energization case from live-island synchronised reconnection.

### A simple example

In a microgrid reconnecting at its point of common coupling, a synchroniser can adjust the island reference while a separate permissive confirms the permitted relationship across the open breaker. For this reference, the drawing identifies “Utility and island voltage conditions” at the input and “Assigned reconnect case” at the output. Loss of sensing must not be interpreted as a dead island.

### What the drawings help you do

Start at the named input: Utility and island voltage conditions. Identify its source device or document and the state represented on the drawing. Follow the named output: Assigned reconnect case. Cross-reference its destination and separate the command from confirmation that the equipment responded.

### Terms

- Input: Utility and island voltage conditions
- Output: Assigned reconnect case
- Application reference: An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.

Concept diagram: Utility and island voltage conditions → MDUI → Assigned reconnect case
A reading guide. The entry's original illustration and input/output facts describe this application.

- [Microgrid Flex components and control design](https://productinfo.se.com/microgrid_guide/0100db2503_ecostruxure-microgrid-flex_design-guide_iec/English/0100DB2503-Microgrid%20Flex%20Design%20Guide-IEC-Optimize%20%28bookmap%29_DD00654397.XML.xml/%24/MicrogridFlexComponents-3A7DD96C)


## What it represents

Distinguishes the documented dead-island energization case from live-island synchronised reconnection. Synchronising control compares two AC systems before their assigned connecting breaker closes. Voltage magnitude, frequency, phase relationship, breaker readiness and command authority are separate inputs to the closing decision.
In a microgrid reconnecting at its point of common coupling, a synchroniser can adjust the island reference while a separate permissive confirms the permitted relationship across the open breaker. For this reference, the drawing identifies “Utility and island voltage conditions” at the input and “Assigned reconnect case” at the output. Loss of sensing must not be interpreted as a dead island.
Identify the two measurement sides and the equipment receiving any adjustment request. Closing limits, breaker timing and loss-of-measurement behavior require the approved synchronising 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.

## How to read it

- Start at the named input: Utility and island voltage conditions. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Assigned reconnect case. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- Loss of sensing must not be interpreted as a dead island.
- Identify the two measurement sides and the equipment receiving any adjustment request. Closing limits, breaker timing and loss-of-measurement behavior require the approved synchronising design.

## Information to show or reference

- Label the source and connection reference for utility and island voltage conditions.
- Identify the destination and defined state of assigned reconnect case.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: Loss of sensing must not be interpreted as a dead island.

## Important distinction

Loss of sensing must not be interpreted as a dead island. 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: Utility and island voltage conditions
- Output / connection: Assigned reconnect case
- Lookup label: MDUI is a library lookup label, not a standard device designation.

## Public references

- [Microgrid Flex components and control design](https://productinfo.se.com/microgrid_guide/0100db2503_ecostruxure-microgrid-flex_design-guide_iec/English/0100DB2503-Microgrid%20Flex%20Design%20Guide-IEC-Optimize%20%28bookmap%29_DD00654397.XML.xml/%24/MicrogridFlexComponents-3A7DD96C) — Schneider Electric. Public technical context for microgrid synchronising interfaces. Microgrid power and control interfaces, synchronisation and source coordination. 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.