IEEE / ANSI · NO UNLATCH

ANSI/IEEE Manually unlatched NO contact form

IEEE-library form of manually unlatched no contact: a manually unlatched NO contact includes a mechanical retaining action released by a documented manual operation.

In plain English

What does ANSI/IEEE Manually unlatched NO contact form mean?

This reference locates manually unlatched no contact in Autodesk's IEEE-oriented relays and contacts family. A manually unlatched normally open contact includes a mechanical retaining action released by a documented manual operation. Its schematic modifier explains why removal of an initiating signal may not restore the initial state. The public library uses HCR2121F for its horizontal representation; this is a vendor block name, not an IEEE standards symbol number.

A simple example

Trace the measured quantity or initiating control signal separately from the output contacts. The device tag links the sensing or operating element to the controlled circuit; settings, reset behaviour and the actual terminal arrangement belong in the selected equipment documentation.

Identify the device and formRead the connections and stateCheck the equipment reference
A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.

What the drawings help you do

Follow the manual reset to the retaining device tag. Manual unlatching concerns the mechanism, not the contact's load interrupting rating. The linked functional counterpart explains the same operating role in its own drawing context; agreement of every detailed convention mark is not asserted.

This particular reference

IEEE-library form of manually unlatched no contact: a manually unlatched normally open contact includes a mechanical retaining action released by a documented manual operation. Manual unlatching concerns the mechanism, not the contact's load interrupting rating.

Normally open / normally closed
The contact state in the normal condition defined for the drawing.
Coil
A wound conductor that can produce a magnetic field when energised.
Terminal
An identified point where a conductor connects.

Read the source: Autodesk IEEE Symbol Preview — Relays and Contacts

IEEE / ANSI · With Mechanical Block and Manual Unlatching

Autodesk IEEE Symbol Preview: Relays and Contacts, block HCR2121F. Matching functional counterpart linked separately. Independently drawn educational geometry; not a certified IEEE glyph or database identifier.

Shown as an independently authored educational illustration. Use the cited publication and drawing legend to verify the required drafting form.

Schematic · NO UNLATCHANSI/IEEE Manually unlatched NO contact form: original educational illustration
Original educational illustrationNot to scale · See source and graphic notes

What it represents

This reference locates manually unlatched no contact in Autodesk's IEEE-oriented relays and contacts family. A manually unlatched NO contact includes a mechanical retaining action released by a documented manual operation. Its schematic modifier explains why removal of an initiating signal may not restore the initial state. The public library uses HCR2121F for its horizontal representation; this is a vendor block name, not an IEEE standards symbol number.

Trace the measured quantity or initiating control signal separately from the output contacts. The device tag links the sensing or operating element to the controlled circuit; settings, reset behaviour and the actual terminal arrangement belong in the selected equipment documentation.

Follow the manual reset to the retaining device tag. Manual unlatching concerns the mechanism, not the contact's load interrupting rating. The linked functional counterpart explains the same operating role in its own drawing context; agreement of every detailed convention mark is not asserted.

How to read it

  • Follow the manual reset to the retaining device tag.
  • The preview is an original explanation of this function. Match the actual drawing convention to its legend and the selected equipment documentation.

Information to show or reference

  • Identify latch mechanism
  • Show manual unlatch
  • Reference contact terminals

A distinction that matters

Manual unlatching concerns the mechanism, not the contact's load interrupting rating.

Sources you can follow

These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.

Autodesk IEEE Symbol Preview — Relays and Contacts

Public IEEE-oriented Relays and Contacts table explicitly lists HCR2121F as With Mechanical Block and Manual Unlatching. This supports the vendor convention context, not reproduction of the publisher graphic.

Autodesk · Public reference checked 14 October 2026 · Link only

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. DXF uses unscaled drawing units; a GA envelope supplies no product dimensions, clearances or fabrication information. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.

Entry JSON · Entry Markdown · Last editorial update: 28 October 2026

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