IEC 60947-5-8-2020 pdf free download – Low-voltage switchgear and controlgear – Part 5-8: Control circuit devices and switching elements – Three-position enabling switches.
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 9.2.3.9 of IEC 60204-1 :201 6 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).
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 – Test Ea and guidance:Shock
EC 60947-1 :2020, Low-voltage switchgear and controlgear – Part 1: General rules
IEC 60947-5-1 :201 6, Low-voltage switchgear and controlgear – 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 :201 6, and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.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 -1 5-21 , 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
3.5
auxiliary contact
contact of a three-position enabling switch that provides an auxiliary function Note 1 to entry: Auxiliary contacts can be normally open and/or normally closed.
3.6
enabling contact
contact of a three-position enabling switch, which is closed when the actuator is in the mid position (partly depressed, position 2 in Figure 1 ) and is open when the actuator is in the rest position (not pressed, position 1 in Figure 1 ) and in the fully depressed position (position 3 in Figure 1 ).IEC 60947-5-8 pdf download.