Low-voltage switchgear and controlgear – Part 5-8: Control circuit devices and switching elements – Three-position enabling switches
|Publication Date:||1 August 2020|
|ICS Code (Low voltage switchgear and controlgear):||29.130.20|
This part of IEC 60947 series specifies requirements for three-position enabling switches.
These switches are used as components of enabling devices to provide signals that,
a) when activated, allow machine operation to be initiated by a separate start control, and
b) when de-activated,
- initiate a stop function, and
- prevent initiation of machine operation.
NOTE 1 The enabling control function is described in 18.104.22.168 of IEC 60204-1:2016 but the application of threeposition enabling switches is not limited to a component of the enabling device described in 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:
- push-button enabling devices;
- grip actuated enabling devices;
- foot actuated enabling devices.
See Annex A for more typical examples.
This document does not apply to:
- three-position enabling switches for non-electrical control circuits, for example hydraulic, pneumatic;
- enabling switches without three-position mechanism;
- emergency stop devices (see IEC 60947-5-5).