IEC 60947-5-8-2020 Low-voltage switchgear and controlgear – Part 5-8: Control circuit devices and switching elements – 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 9.2.3.9 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
250VAC50Hz/60Hzor300VDC.
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).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
IEC 60068-2-1:2007, Environmental testing- Part 2-1: Tests- Test A: Cold
IEC 60068-2-2:2007, Environmental testing- Part 2-2: Tests – Test B: Dry heat
IEC 60068-2-6:2007. Environmental testing – Part 2-6: Tests – Test Fc: Vibration (sinusoidal)
IEC 60068-2-27:2008, Environmental testing – Part 2-27: Tests 一Test Ea and guidance: Shock
IEC 60947-1:2020, Low-voltage switchgear and controlgear – Part 1: General rules
IEC 60947-5-1:2016，Low-voltage switchgear and controlgear 一Part 5-1: Control circuit devices and switching elements – Electromechanical control circuit devices
3 Terms and definitions
For the purposes of this document, the terms and definitions given in Clause 3 of IEC 60947-1:2020 and Clause 2 of IEC 60947-5-1:2016, and the following apply.
Iso and IEC maintain terminological databases for use in standardization at the following addresses:
●IEC Electropedia: available at ht://ww.electropedia.org/
●ISO Online browsing platform: available at ht://ww.iso.org/obp
Alphabetical index of definitions
3.1 enabling device
manually operated control device used in conjunction with a start control and which, when continuously actuated, allows a machine operation
3.2 three-position enabling switch
three-position switch having enabling contact(s)
3.3 actuating system
<three-position enabling switch> all the mechanical parts which transmit the actuating force to the contact elements
[SOURCE: IEC 60050-441:2000, 441-15-21, modified – “all the operating means of a control switch” replaced by “all the mechanical parts”, note to entry deleted.]
3.4 actuator
<three-position enabling switch> part of the actuating system which is actuated by a part of the human body.IEC 60947-5-8 pdf download.