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 · DBOB
Digital breaker-command output boundary
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
Shows the conversion from a received digital operating request to the assigned physical breaker output.
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 “Accepted digital command” at the input and “Physical operating output” at the output. The output circuit still requires its normal supervision.
What the drawings help you do
Start at the named input: Accepted digital command. Identify its source device or document and the state represented on the drawing. Follow the named output: Physical operating output. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- Input
- Accepted digital command
- Output
- Physical operating output
- 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 · DBOB
What it represents
Shows the conversion from a received digital operating request to the assigned physical breaker output. 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 “Accepted digital command” at the input and “Physical operating output” at the output. The output circuit still requires its normal supervision.
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: Accepted digital command. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Physical operating output. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- The output circuit still requires its normal supervision.
- 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 accepted digital command.
- Identify the destination and defined state of physical operating output.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: The output circuit still requires its normal supervision.
A distinction that matters
The output circuit still requires its normal supervision. 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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