Low-voltage switchgear and controlgear - Control circuit devices and switching elements. Three-position enabling switches

Low-voltage switchgear and controlgear - Control circuit devices and switching elements. Three-position enabling switches

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1   Scope

This part of IEC 60947 series specifies requirements for three-position enabling switches.
These switches are used as components of enabling devices described in [no rendering defined for element: related-object ] 10.9 of IEC 60204‑1 to provide signals that,
  1. a) when activated, allow machine operation to be initiated by a separate start control, and
  2. b) when de-activated,
    1. – initiate a stop function, and
    2. – prevent initiation of machine operation.

NOTE 1 The enabling control function is described in 9.2.6.3 9.2.3.9 of IEC 60204‑1:2016but the application of three-position enabling switches is not limited to a component of the enabling device described in [no rendering defined for element: related-object ] IEC 60204‑1.

NOTE 2 This document does not deal with enabling devices.

These switches are intended to be connected to circuits which rated voltage does not exceed 250 V AC 50 Hz/60 Hz or 300 V DC.

EXAMPLE

Devices incorporating three-position enabling switches are:
  1. – push-button enabling devices;
  2. – grip actuated enabling devices;
  3. – foot actuated enabling devices.
See Annex A for more typical examples.
This document does not apply to:
  1. – three-position enabling switches for non-electrical control circuits, for example hydraulic, pneumatic;
  2. – enabling switches without three-position mechanism;
  3. – emergency stop devices (see IEC 60947‑5‑5).