CVT / CCVT
Capacitor voltage transformer
An instrument transformer using a capacitive voltage divider and an electromagnetic unit to supply documented voltage measurement or protection signals.
SLD / Schematic
Functional block · CTI
Carrier transmit-enable input
Functional block · Switchyards
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.
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What this block does
Identifies the selected protection condition that permits carrier transmission.
A simple example
In a switchyard line bay, carrier-coupling equipment can connect a protection communication terminal to the transmission conductor. Fiber-based protection uses another physical path but still needs named endpoints and channel supervision. For this reference, the drawing identifies “Protection communication initiation” at the input and “Carrier transmit request” at the output. The receiving scheme defines the message meaning.
What the drawings help you do
Start at the named input: Protection communication initiation. Identify its source device or document and the state represented on the drawing. Follow the named output: Carrier transmit request. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- Input
- Protection communication initiation
- Output
- Carrier transmit request
- Application reference
- An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.
Read the source: Line traps: power-line carrier communication
Schematic · CTI
What it represents
Identifies the selected protection condition that permits carrier transmission. A protection communication interface carries information between circuit ends or couples a communication signal to a primary line. Its signal path is different from the power-current path even when both use part of the same installation.
In a switchyard line bay, carrier-coupling equipment can connect a protection communication terminal to the transmission conductor. Fiber-based protection uses another physical path but still needs named endpoints and channel supervision. For this reference, the drawing identifies “Protection communication initiation” at the input and “Carrier transmit request” at the output. The receiving scheme defines the message meaning.
Show each coupling boundary and the intended information direction. Frequency selection, channel performance, insulation duty and protective coordination require the selected communication and primary equipment 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: Protection communication initiation. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Carrier transmit request. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- The receiving scheme defines the message meaning.
- Show each coupling boundary and the intended information direction. Frequency selection, channel performance, insulation duty and protective coordination require the selected communication and primary equipment design.
Information to show or reference
- Label the source and connection reference for protection communication initiation.
- Identify the destination and defined state of carrier transmit request.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: The receiving scheme defines the message meaning.
A distinction that matters
The receiving scheme defines the message meaning. 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.
Line traps: power-line carrier communication
Public technical context for line carrier and protection communication interfaces. Line traps, coupling and power-line carrier communications. 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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