# Dedicated bus-protection CT core interface

Canonical URL: https://eloragrid.ai/symbols/dedicated-bus-protection-ct-core-interface
Publisher: Elora Grid
Updated: 2026-11-03
Lookup label: DBCCI
Drawing use: Schematic
Reference families: Manufacturer

Representation: Functional block
Installation focus: substations
Input: Bus-zone CT core
Output: Bus-protection input

Defines the CT secondary path allocated to the bus protection measurement zone.

## In plain English

### What this block does

Defines the CT secondary path allocated to the bus protection measurement zone.

### A simple example

In a substation protection panel, separate CT cores can supply metering and protection circuits with different duties. A test boundary must preserve the secondary arrangement required by the selected CT and test device. For this reference, the drawing identifies “Bus-zone CT core” at the input and “Bus-protection input” at the output. CT location establishes the zone boundary.

### What the drawings help you do

Start at the named input: Bus-zone CT core. Identify its source device or document and the state represented on the drawing. Follow the named output: Bus-protection input. Cross-reference its destination and separate the command from confirmation that the equipment responded.

### Terms

- Input: Bus-zone CT core
- Output: Bus-protection input
- Application reference: An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.

Concept diagram: Bus-zone CT core → DBCCI → Bus-protection input
A reading guide. The entry's original illustration and input/output facts describe this application.

- [Indoor current and voltage transformers](https://www.abb.com/gb/en/areas/electrification/medium-voltage/grid-components/core-components/indoor-instrument-transformers)


## What it represents

Defines the CT secondary path allocated to the bus protection measurement zone. A current-transformer secondary arrangement carries a measuring current from a defined primary location to metering or protection inputs. Core identity, polarity and the connected circuit determine the measurement's meaning.
In a substation protection panel, separate CT cores can supply metering and protection circuits with different duties. A test boundary must preserve the secondary arrangement required by the selected CT and test device. For this reference, the drawing identifies “Bus-zone CT core” at the input and “Bus-protection input” at the output. CT location establishes the zone boundary.
Trace every secondary connection and the assigned earthing point against the actual connection diagram. These illustrations explain circuit roles and never prescribe a live CT switching or disconnection procedure. 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: Bus-zone CT core. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Bus-protection input. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- CT location establishes the zone boundary.
- Trace every secondary connection and the assigned earthing point against the actual connection diagram. These illustrations explain circuit roles and never prescribe a live CT switching or disconnection procedure.

## Information to show or reference

- Label the source and connection reference for bus-zone ct core.
- Identify the destination and defined state of bus-protection input.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: CT location establishes the zone boundary.

## Important distinction

CT location establishes the zone boundary. 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: Substations
- Input / boundary: Bus-zone CT core
- Output / connection: Bus-protection input
- Lookup label: DBCCI is a library lookup label, not a standard device designation.

## Public references

- [Indoor current and voltage transformers](https://www.abb.com/gb/en/areas/electrification/medium-voltage/grid-components/core-components/indoor-instrument-transformers) — ABB. Public technical context for current-transformer secondary arrangements. Current and voltage measurement transformers and their secondary interfaces. 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.