Understand the difference.

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

TON NC

IEEE / ANSI

ANSI/IEEE on-delay normally-closed contact symbol

The on-delay NC contact form specifically describes delayed opening from its reference closed state. The controlled path remains continuous while the specified delay runs, so the timer tag and timing condition are essential circuit-reading information.

Drawing use

Schematic

Application

Control circuits

Reference family

IEEE / ANSI / Manufacturer

Form evidence

Autodesk IEEE-oriented Time Delay Relays functional form. Autodesk explicitly publishes this block under IEEE Symbol Preview. The counterpart is the matching functional concept; no equivalence of every detailed standard graphic is asserted.

A distinction that matters

Normally closed describes the initial contact state while on-delay identifies the specified operating transition.

Full referenceAdd to legend

TON NC

Symbols

On-delay normally-closed contact

An on-delay NC contact opens after the associated timing condition has persisted for its documented interval. Its unoperated closed state is read separately from the timing annotation.

Drawing use

Schematic

Application

Control circuits

Reference family

IEC / Manufacturer

A distinction that matters

An on-delay NC contact is not an off-delay NO contact even if a sequence produces similar output timing.

Full referenceAdd to legend

Original educational previews. Follow the source references on each full entry for the appropriate standard or selected product.