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Synchronism check
Checks documented synchronising conditions before a permitted connection.
Protection functions
Functional block · MDIR
Microgrid dead-utility island-close restraint
Functional block · Microgrids
An independently authored application reference. The drawing shows the named function or circuit relationship; use the project legend and selected equipment documentation for its drafting form and connections.
Browse this installation focusIn plain English
What this block does
Identifies the specified restraint on connecting an energized island to an unavailable utility circuit.
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 “Island voltage and utility condition” at the input and “Interconnection closing restraint” at the output. Connection permission follows the network agreement.
What the drawings help you do
Start at the named input: Island voltage and utility condition. Identify its source device or document and the state represented on the drawing. Follow the named output: Interconnection closing restraint. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- Input
- Island voltage and utility condition
- Output
- Interconnection closing restraint
- Application reference
- An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.
Read the source: Microgrid Flex components and control design
Schematic · MDIR
What it represents
Identifies the specified restraint on connecting an energized island to an unavailable utility circuit. 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 “Island voltage and utility condition” at the input and “Interconnection closing restraint” at the output. Connection permission follows the network agreement.
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: Island voltage and utility condition. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Interconnection closing restraint. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- Connection permission follows the network agreement.
- 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 island voltage and utility condition.
- Identify the destination and defined state of interconnection closing restraint.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: Connection permission follows the network agreement.
A distinction that matters
Connection permission follows the network agreement. 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.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
Microgrid Flex components and control design
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.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
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