# Protection channel asymmetric-delay indication

Canonical URL: https://eloragrid.ai/symbols/protection-channel-asymmetric-delay-indication
Publisher: Elora Grid
Updated: 2026-11-03
Lookup label: PCAI
Drawing use: Schematic
Reference families: Manufacturer

Representation: Functional block
Installation focus: switchyards
Input: Directional delay information
Output: Asymmetry indication

Identifies a measured or declared difference between the communication path directions.

## In plain English

### What this block does

Identifies a measured or declared difference between the communication path directions.

### 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 “Directional delay information” at the input and “Asymmetry indication” at the output. Compensation depends on the selected protection implementation.

### What the drawings help you do

Start at the named input: Directional delay information. Identify its source device or document and the state represented on the drawing. Follow the named output: Asymmetry indication. Cross-reference its destination and separate the command from confirmation that the equipment responded.

### Terms

- Input: Directional delay information
- Output: Asymmetry indication
- Application reference: An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.

Concept diagram: Directional delay information → PCAI → Asymmetry indication
A reading guide. The entry's original illustration and input/output facts describe this application.

- [Line traps: power-line carrier communication](https://www.gevernova.com/grid-solutions/sites/default/files/2025-09/Line-Traps-Brochure-EN-N50059-Hybrid-202504-R002.pdf)


## What it represents

Identifies a measured or declared difference between the communication path directions. 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 “Directional delay information” at the input and “Asymmetry indication” at the output. Compensation depends on the selected protection implementation.
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: Directional delay information. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Asymmetry indication. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- Compensation depends on the selected protection implementation.
- 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 directional delay information.
- Identify the destination and defined state of asymmetry indication.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: Compensation depends on the selected protection implementation.

## Important distinction

Compensation depends on the selected protection implementation. 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.

## Facts

- Representation: Functional block
- Installation focus: Switchyards
- Input / boundary: Directional delay information
- Output / connection: Asymmetry indication
- Lookup label: PCAI is a library lookup label, not a standard device designation.

## Public references

- [Line traps: power-line carrier communication](https://www.gevernova.com/grid-solutions/sites/default/files/2025-09/Line-Traps-Brochure-EN-N50059-Hybrid-202504-R002.pdf) — GE Vernova. 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.

## Graphic scope

Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.