Side-by-side reference

Understand the difference.

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

First referenceCompare with

OL NC

Symbols

Motor overload trip NC contact

An overload trip NC contact opens on the documented overload relay operation. It is commonly wired in the motor-control path while the overload sensing elements belong to the power circuit.

Drawing use: Schematic
Application: Control circuits
Reference family: IEC / Manufacturer

A distinction that matters

The auxiliary overload contact interrupts a control path; it does not itself carry the motor feeder current.

Full reference

Symbols

Normally open contact

A normally open contact is open in the normal state defined for the device. Operating its relay, pushbutton or other parent device may close the contact. The meaning of normal must be established from the drawing convention and equipment documentation; it is not necessarily the current live condition of the installation.

Drawing use: Schematic
Application: Control circuits
Reference family: IEC / IEEE / ANSI

A distinction that matters

Normally open describes the stated normal condition. A position indication or operating snapshot may use a different state convention.

Full reference

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