# Microgrid synchronising frequency-error block

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

Representation: Functional block
Installation focus: microgrids
Input: Two frequency measurements
Output: Synchronising frequency error

Calculates the defined frequency difference across the assigned open interconnection breaker.

## In plain English

### What this block does

Calculates the defined frequency difference across the assigned open interconnection breaker.

### 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 “Two frequency measurements” at the input and “Synchronising frequency error” at the output. The sign convention must be identified.

### What the drawings help you do

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

### Terms

- Input: Two frequency measurements
- Output: Synchronising frequency error
- Application reference: An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.

Concept diagram: Two frequency measurements → MSFB → Synchronising frequency error
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

Calculates the defined frequency difference across the assigned open interconnection breaker. 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 “Two frequency measurements” at the input and “Synchronising frequency error” at the output. The sign convention must be identified.
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: Two frequency measurements. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Synchronising frequency error. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- The sign convention must be identified.
- 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 two frequency measurements.
- Identify the destination and defined state of synchronising frequency error.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: The sign convention must be identified.

## Important distinction

The sign convention must be identified. 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: Two frequency measurements
- Output / connection: Synchronising frequency error
- Lookup label: MSFB 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.