# Microgrid synchronising close-permissive block

Canonical URL: https://eloragrid.ai/symbols/microgrid-synchronising-close-permissive-block
Publisher: Elora Grid
Updated: 2026-11-03
Lookup label: MSCB
Drawing use: Schematic
Reference families: Manufacturer

Representation: Functional block
Installation focus: microgrids
Input: Synchronising checks
Output: PCC close permission

Combines the specified synchronising conditions into the assigned breaker-closing permission.

## In plain English

### What this block does

Combines the specified synchronising conditions into the assigned breaker-closing permission.

### 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 “Synchronising checks” at the input and “PCC close permission” at the output. The permissive is not the final coil output.

### What the drawings help you do

Start at the named input: Synchronising checks. Identify its source device or document and the state represented on the drawing. Follow the named output: PCC close permission. Cross-reference its destination and separate the command from confirmation that the equipment responded.

### Terms

- Input: Synchronising checks
- Output: PCC close permission
- Application reference: An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.

Concept diagram: Synchronising checks → MSCB → PCC close permission
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

Combines the specified synchronising conditions into the assigned breaker-closing permission. 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 “Synchronising checks” at the input and “PCC close permission” at the output. The permissive is not the final coil output.
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: Synchronising checks. Identify its source device or document and the state represented on the drawing.
- Follow the named output: PCC close permission. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- The permissive is not the final coil output.
- 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 synchronising checks.
- Identify the destination and defined state of pcc close permission.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: The permissive is not the final coil output.

## Important distinction

The permissive is not the final coil output. 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: Synchronising checks
- Output / connection: PCC close permission
- Lookup label: MSCB 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.