Relay: labelled reference, IEC style

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Relay: labelled reference, IEC style, sheet 1 of 1

  1. Fig. 1

    COMNCNOA1A2

    Relay (coil and SPDT contact)

    The electromechanical relay shown here uses a coil to move contacts. Its coil circuit is electrically separate from the switched contact circuit.

Terminal key
Fig.TerminalsWhat the terminal is
1COMCOM is the common contact, the one the moving arm belongs to.
1NCNC is the normally-closed contact: it is connected to COM in the resting, de-energised state of the single-stable relay shown here.
1NONO is the normally-open contact: it is disconnected from COM at rest and connected after the coil has energised the single-stable relay shown here.
1A1, A2The two coil terminals are the control side of the relay; the current that flows through them moves the contacts.

Sources

  1. ModEL — Electromechanical Relays, §§3.2–3.3 and §5.1 (normal and present contact status), Tony R. Kuphaldt, retrieved 2026-09-22
  2. Relay technology — structure, operation and contact forms, Omron, retrieved 2026-09-22
  3. AT121 course notes — Relays: ISO relay contact numbers, Community College of Philadelphia (D. Reed), reproducing with permission an MG Car Club article by Rick Astley, retrieved 2026-09-23
  4. ModEL — Components and Symbols, §3.11 (relay symbol, p. 21), Tony R. Kuphaldt, retrieved 2026-09-23
Name
Class
Date
Sheet
1 of 1
Drawing
Relay Labelled reference
Style
IEC style
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CC BY 4.0