PCC
Point of common coupling
A marker on a single-line diagram identifying where a customer installation or microgrid meets the public network.
SLD
Symbols · MIS
Microgrid interconnection switch
The switching device that separates a microgrid from the utility for islanding and reconnects it after synchronising.
In plain English
What does Microgrid interconnection switch mean?
The microgrid interconnection switch is the breaker or switch at the boundary with the utility that opens to island the microgrid and closes to reconnect it. Its control is tied to interface protection, which detects loss of mains, and to the microgrid controller, which manages planned islanding and resynchronisation.
A simple example
Single-line diagrams show a circuit breaker at the point of common coupling with protection functions listed beside it, commonly under and over voltage, under and over frequency, rate of change of frequency, directional power and synchronism check. A label such as MIS or island breaker identifies its role.
What the drawings help you do
The breaker itself is an ordinary device; its function comes from the protection and control logic. The symbol does not show whether reconnection is automatic, how long it waits or whether a seamless transition is possible.
This particular reference
The switching device that separates a microgrid from the utility for islanding and reconnects it after synchronising. The interconnection switch defines the island boundary; a generator breaker connects only one source.
- Terminal
- An identified point where a conductor connects.
- Signal
- Electrical information passed between devices, rather than necessarily the main power supply.
- Rating
- A value stating the conditions for which equipment is specified.
Read the source: Reliable hybrid power and microgrid solutions · Public reference table of ANSI device-function numbers
SLD · MIS
What it represents
The microgrid interconnection switch is the breaker or switch at the boundary with the utility that opens to island the microgrid and closes to reconnect it. Its control is tied to interface protection, which detects loss of mains, and to the microgrid controller, which manages planned islanding and resynchronisation.
Single-line diagrams show a circuit breaker at the point of common coupling with protection functions listed beside it, commonly under and over voltage, under and over frequency, rate of change of frequency, directional power and synchronism check. A label such as MIS or island breaker identifies its role.
The breaker itself is an ordinary device; its function comes from the protection and control logic. The symbol does not show whether reconnection is automatic, how long it waits or whether a seamless transition is possible.
How to read it
- Read the protection functions listed beside the breaker.
- Synchronism check must supervise closing.
Information to show or reference
- State interface protection functions and settings source.
- Show synchronism check and controller link.
- Reference islanding and reconnection logic.
A distinction that matters
The interconnection switch defines the island boundary; a generator breaker connects only one source.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
Reliable hybrid power and microgrid solutions
Public microgrid control context with mains interaction.
Public reference table of ANSI device-function numbers
Public device-function number table for interface protection functions.
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. DXF uses unscaled drawing units; a GA envelope supplies no product dimensions, clearances or fabrication information. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
Explore related references
MGC
Microgrid controller
The supervisory controller that dispatches sources, storage and loads and manages islanding and reconnection of a microgrid.
SLD / Schematic
25
Synchronism check
Checks documented synchronising conditions before a permitted connection.
Protection functions
81R
Rate-of-change-of-frequency protection
Supervises the rate at which measured electrical frequency changes.
Protection functions
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