IED
Numerical protection relay (IED)
Single relay block on an SLD that lists the protection functions it provides, with CT, VT and trip connections.
SLD / Schematic
Functional block · PLI
Process-network link-health input
Functional block · Substations
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
Reports the defined physical or logical link condition on the assigned process-network connection.
A simple example
In a digital substation bay, a merging unit digitizes local measurements and a protective relay subscribes to the assigned data stream. The command return path and communication-health indications are drawn separately. For this reference, the drawing identifies “Network port health” at the input and “Process-link alarm” at the output. A healthy link can still carry invalid application data.
What the drawings help you do
Start at the named input: Network port health. Identify its source device or document and the state represented on the drawing. Follow the named output: Process-link alarm. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- Input
- Network port health
- Output
- Process-link alarm
- Application reference
- An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.
Read the source: Digital secondary systems: Sampled Values
Schematic · PLI
What it represents
Reports the defined physical or logical link condition on the assigned process-network connection. Digital substation interfaces carry measurements, status and control information between primary equipment and protective devices. Measurement streams, event messages and time synchronization are separate dependencies even when they share an Ethernet network.
In a digital substation bay, a merging unit digitizes local measurements and a protective relay subscribes to the assigned data stream. The command return path and communication-health indications are drawn separately. For this reference, the drawing identifies “Network port health” at the input and “Process-link alarm” at the output. A healthy link can still carry invalid application data.
Identify publisher, subscriber, data meaning and quality handling. Protocol labels alone do not establish protection performance, compatibility or network redundancy; these need the selected system configuration and validation. 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: Network port health. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Process-link alarm. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- A healthy link can still carry invalid application data.
- Identify publisher, subscriber, data meaning and quality handling. Protocol labels alone do not establish protection performance, compatibility or network redundancy; these need the selected system configuration and validation.
Information to show or reference
- Label the source and connection reference for network port health.
- Identify the destination and defined state of process-link alarm.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: A healthy link can still carry invalid application data.
A distinction that matters
A healthy link can still carry invalid application data. 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.
Digital secondary systems: Sampled Values
Public technical context for digital substation process interfaces. Merging units, sampled measurements, GOOSE, process bus and network redundancy. 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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