# Centre-break disconnector application reference

Canonical URL: https://eloragrid.ai/symbols/centre-break-disconnector-application-reference
Publisher: Elora Grid
Updated: 2026-11-03
Lookup label: CDAR
Drawing use: Schematic
Reference families: Manufacturer

Representation: Functional block
Installation focus: switchyards
Input: Primary terminal pair
Output: Centre-break isolation function

Identifies the documented disconnector construction with its defined centre-opening contact arrangement.

## In plain English

### What this block does

Identifies the documented disconnector construction with its defined centre-opening contact arrangement.

### A simple example

In a switchyard bay, a bus selector can use a different physical construction from a line disconnector. Each device still needs an identified operating mechanism, position indication and interlocking interface. For this reference, the drawing identifies “Primary terminal pair” at the input and “Centre-break isolation function” at the output. The construction does not imply fault-interruption capability.

### What the drawings help you do

Start at the named input: Primary terminal pair. Identify its source device or document and the state represented on the drawing. Follow the named output: Centre-break isolation function. Cross-reference its destination and separate the command from confirmation that the equipment responded.

### Terms

- Input: Primary terminal pair
- Output: Centre-break isolation function
- Application reference: An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.

Concept diagram: Primary terminal pair → CDAR → Centre-break isolation function
A reading guide. The entry's original illustration and input/output facts describe this application.

- [Disconnectors and earthing switches](https://www.siemens-energy.com/global/en/home/products-services/product-offerings/disconnectors-earthing-switches.html)


## What it represents

Identifies the documented disconnector construction with its defined centre-opening contact arrangement. Disconnector and earthing references identify different mechanical constructions and connection duties within a yard. The primary diagram shows which conductors are joined or earthed; the equipment drawing explains how its contacts and supports move.
In a switchyard bay, a bus selector can use a different physical construction from a line disconnector. Each device still needs an identified operating mechanism, position indication and interlocking interface. For this reference, the drawing identifies “Primary terminal pair” at the input and “Centre-break isolation function” at the output. The construction does not imply fault-interruption capability.
The construction name does not establish load-breaking capability, short-circuit making duty or operating permission. Verify these properties in the selected equipment data and the station interlocking scheme. 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: Primary terminal pair. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Centre-break isolation function. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- The construction does not imply fault-interruption capability.
- The construction name does not establish load-breaking capability, short-circuit making duty or operating permission. Verify these properties in the selected equipment data and the station interlocking scheme.

## Information to show or reference

- Label the source and connection reference for primary terminal pair.
- Identify the destination and defined state of centre-break isolation function.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: The construction does not imply fault-interruption capability.

## Important distinction

The construction does not imply fault-interruption capability. 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: Primary terminal pair
- Output / connection: Centre-break isolation function
- Lookup label: CDAR is a library lookup label, not a standard device designation.

## Public references

- [Disconnectors and earthing switches](https://www.siemens-energy.com/global/en/home/products-services/product-offerings/disconnectors-earthing-switches.html) — Siemens Energy. Public technical context for disconnector and earthing applications. Disconnector construction, earthing switches and operating mechanisms. 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.