IEC 60947-3:2020 pdf free.Low-voltage switchgear and controlgear – Switches, disconnectors, switch-disconnectors and fuse-combination units.
The utilization categories define the intended applications and are given in Table 2.
Each utilization category is characterized by the values of the currents and voltages,expressed as multiples of the rated operational current and the rated operational voltage,aswell as the power-factors or time-constants of the circuit. The conditions for making andbreaking given in Table 4 correspond in principle to the applications listed in Table 2.
The designation of utilization categories is completed by the suffix A or B according towhether the intended applications require frequent or infrequent operations (see Table 5).
Utilization categories with suffix B are appropriate for devices which,due to design orapplication,are only intended for infrequent operation. This could apply,for example,todisconnectors normally only operated to provide isolation for maintenance work or switchingdevices where the fuse-link blade forms the moving contact.
The distinction between frequent and infrequent operation is based on the manufacturer’srated operation and the number of operating cycles used as a test criterion in Table 5.
For a particular rated operational current l., a device will be designated for frequent use(category A) if the manufacturer’s declared number of operating cycles is equal to or morethan the number of operating cycles indicated in columns 3,4 and 5 of Table 5.
When hazardous emissions including optical emissions are produced during switchingoperations, the recommendations as given in the manufacturer’s instructions in respect ofinstallation and/or the use of personal protective equipment (PPE) shall be observed.
Clause 7 of lEC 60947-1:2020 applies with the replacement of the paragraph under theheading “Standard pollution degree of industrial applications:” in “Pollution degree”with the following:
Unless otherwise stated by the manufacturer, the equipment is intended for installation underenvironmental conditions of pollution degree 3.
Subclause 8.1 of lEC 60947-1:2020 applies, with the following additions.
Specific requirements for LV switchgear intended for the connections of aluminium conductorsis given in Annex E.
When switches and fuse-combination units coming into the scope of this document arenormally used to start, accelerate and/or stop an individual motor, they shall also comply withthe additional requirements given in Annex A.
The requirements for single pole operated three-pole switches are included in Annex C.
Auxiliary switches fitted to equipment within the scope of this document shall comply with therequirements of lEC 60947-5-1.
Subclause of lEC 60947-1:2020 applies with the following changes and additions.
Parts of insulating material necessary to retain current-carrying parts in position shall conformto the glow-wire tests of of lEC 60947-1:2020 for test temperatures as follows:
– main current carrying parts: 96o °c.
– auxiliary current carrying parts: 850 °c.
The requirements of of lEC 60947-1:2020 do not apply to parts with a mass lower than2 g (insignificant mass as defined in 3.14 of lEC 60695-2-11:2014).For products containing aplurality of small parts, the total mass of non-tested parts located in close proximity to eachother shall not exceed 10 g. Proximity shall be based on engineering judgment consideringthe risk of propagation of fire.IEC 60947-3 pdf download.