CB
Circuit breaker
A switching device that can interrupt a circuit, with specified fault-interruption capability.
SLD / Schematic
Functional block · BMCI
Breaker mechanism-operated contact interface
Functional block · Switchgear
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.
Browse this installation focusIn 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.
- 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.
Read the source: Masterclad medium-voltage switchgear: circuit-breaker section interlocks
Schematic · BMCI
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.
A distinction that matters
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.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
Masterclad medium-voltage switchgear: circuit-breaker section interlocks
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.
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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