Q021211
Mechanical interlock between devices
A mechanical interlock indication links devices whose movements are constrained by a physical relationship.
IEC
Functional block · SII
Shutter-access interlock 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
Relates primary-contact shutter position to the documented access restrictions.
A simple example
In a switchgear feeder panel, a control diagram can prevent an incompatible combination of breaker, disconnector and earthing-switch positions. The physical equipment documents determine which restrictions are mechanically enforced. For this reference, the drawing identifies “Shutter and access conditions” at the input and “Access interlock status” at the output. The indication is not authorization to approach live contacts.
What the drawings help you do
Start at the named input: Shutter and access conditions. Identify its source device or document and the state represented on the drawing. Follow the named output: Access interlock status. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- Input
- Shutter and access conditions
- Output
- Access interlock status
- 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 · SII
What it represents
Relates primary-contact shutter position to the documented access restrictions. An interlocking function permits or blocks an operation according to the positions and conditions of related equipment. Electrical, mechanical and trapped-key interlocks implement different parts of a coordinated operating philosophy.
In a switchgear feeder panel, a control diagram can prevent an incompatible combination of breaker, disconnector and earthing-switch positions. The physical equipment documents determine which restrictions are mechanically enforced. For this reference, the drawing identifies “Shutter and access conditions” at the input and “Access interlock status” at the output. The indication is not authorization to approach live contacts.
Identify each initiating position, the action being blocked and the consequence of missing feedback. An illustrative logic diagram must not be treated as an operating procedure or proof of a complete safety system. 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: Shutter and access conditions. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Access interlock status. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- The indication is not authorization to approach live contacts.
- Identify each initiating position, the action being blocked and the consequence of missing feedback. An illustrative logic diagram must not be treated as an operating procedure or proof of a complete safety system.
Information to show or reference
- Label the source and connection reference for shutter and access conditions.
- Identify the destination and defined state of access interlock status.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: The indication is not authorization to approach live contacts.
A distinction that matters
The indication is not authorization to approach live 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 switchgear interlocking functions. 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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