Understand the difference.

Compare the meaning, drawing context and source references of two entries. A similar graphic or shared abbreviation does not establish equivalence.

IFG

Symbols

Invalid-position fail-block gate

Blocks the assigned operation when its required position inputs form an invalid combination. 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.

Drawing use

Schematic

Application

Control circuits

Reference family

Manufacturer

A distinction that matters

The fail response must be agreed for the application. 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.

Full referenceAdd to legend

Q021211

IEC

Mechanical interlock between devices

A mechanical interlock indication links devices whose movements are constrained by a physical relationship. A physical interlock constrains the movements of two associated mechanisms. It remains a mechanical relationship even when the electrical circuit also contains permissive contacts.

Drawing use

Schematic

Application

Control circuits

Reference family

IEC / Manufacturer

Form evidence

Mechanical interlock between devices. Autodesk IEC-60617 Symbol Preview — Mechanical return and interlock qualifiers; vendor family reference, not certified IEC geometry or database identifier.

A distinction that matters

Mechanical interlocking differs from an electrical interlock contact or software permissive.

Full referenceAdd to legend

Follow the full entry for source drawings and the appropriate standard or selected product. Equipment previews show a manufacturer drawing where available, otherwise a 3D thumbnail.