# Breaker mechanism-operated contact interface

Canonical URL: https://eloragrid.ai/symbols/breaker-mechanism-operated-contact-interface
Publisher: Elora Grid
Updated: 2026-11-03
Lookup label: BMCI
Drawing use: Schematic
Reference families: Manufacturer

Representation: Functional block
Installation focus: switchgear
Input: Mechanism movement
Output: MOC auxiliary contacts

Reports the breaker mechanism position through a compartment-mounted mechanism-operated contact assembly.

## In plain English

### What this block does

Reports the breaker mechanism position through a compartment-mounted mechanism-operated contact assembly.

### A simple example

In a switchgear control schematic, the bay controller compares independent status contacts before displaying a position or allowing another operation. The signal labels explain which physical state each contact represents. For this reference, the drawing identifies “Mechanism movement” at the input and “MOC auxiliary contacts” at the output. MOC contacts differ from truck-position contacts.

### What the drawings help you do

Start at the named input: Mechanism movement. Identify its source device or document and the state represented on the drawing. Follow the named output: MOC auxiliary contacts. Cross-reference its destination and separate the command from confirmation that the equipment responded.

### Terms

- Input: Mechanism movement
- Output: MOC auxiliary contacts
- Application reference: An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.

Concept diagram: Mechanism movement → BMCI → MOC auxiliary contacts
A reading guide. The entry's original illustration and input/output facts describe this application.

- [Masterclad medium-voltage switchgear: circuit-breaker section interlocks](https://productinfo.se.com/masterclad_mv_switchgear_ib/6055-30-masterclad-15kv-mv-switchgear-ib/English/6055-30%20Masterclad%20MV%20Switchgear%20Indoor%20%28bookmap%29_DD00646805.xml/%24/Section6-CircuitBreakerSectionInter-58DD6EC7)


## What it represents

Reports the breaker mechanism position through a compartment-mounted mechanism-operated contact assembly. Breaker status indications describe the operating mechanism, the removable truck or the health of a supporting system. These signals are related but are not interchangeable: an open breaker can still have its truck connected to live bus contacts.
In a switchgear control schematic, the bay controller compares independent status contacts before displaying a position or allowing another operation. The signal labels explain which physical state each contact represents. For this reference, the drawing identifies “Mechanism movement” at the input and “MOC auxiliary contacts” at the output. MOC contacts differ from truck-position contacts.
Keep contact reference conditions, terminal numbers and interpretation logic together. Distinguish a mechanically operated indication from a measured current or voltage condition. 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: Mechanism movement. Identify its source device or document and the state represented on the drawing.
- Follow the named output: MOC auxiliary contacts. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- MOC contacts differ from truck-position contacts.
- Keep contact reference conditions, terminal numbers and interpretation logic together. Distinguish a mechanically operated indication from a measured current or voltage condition.

## Information to show or reference

- Label the source and connection reference for mechanism movement.
- Identify the destination and defined state of moc auxiliary contacts.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: MOC contacts differ from truck-position contacts.

## Important distinction

MOC contacts differ from truck-position contacts. 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: Switchgear
- Input / boundary: Mechanism movement
- Output / connection: MOC auxiliary contacts
- Lookup label: BMCI is a library lookup label, not a standard device designation.

## Public references

- [Masterclad medium-voltage switchgear: circuit-breaker section interlocks](https://productinfo.se.com/masterclad_mv_switchgear_ib/6055-30-masterclad-15kv-mv-switchgear-ib/English/6055-30%20Masterclad%20MV%20Switchgear%20Indoor%20%28bookmap%29_DD00646805.xml/%24/Section6-CircuitBreakerSectionInter-58DD6EC7) — Schneider Electric. Public technical context for breaker position and status interfaces. Breaker control, mechanism, position contacts, racking interlocks and test 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.