IEC 60947-4-3-2020 Low-voltage switchgear and controlgear – Part 3: Switches, disconnectors, switch-disconnectors and fuse-combination units.
4 Classification
4.1 According to the utilization category
See 5.4.
4.2 According to the method of operation
4.2.1 Manually operated equipment
– dependent manual operation (see 3.6.1 2 of IEC 60947-1 :2020);
– independent manual operation (see 3.6.1 5 of IEC 60947-1 :2020);
– semi-independent manual operation (see 3.3.1 0).
4.2.2 Remotely operated equipment
Under consideration.
4.3 According to suitability for isolation
– suitable for isolation (see 8.1 .7 of IEC 60947-1 :2020);
– not suitable for isolation.
4.4 According to the degree of protection provided
See 8.1 .1 2 of IEC 60947-1 :2020.
4.5 Summary of symbols for equipment types
A summary of equipment definitions and relevant diagrams is given in Table 1 .
5 Characteristics
5.1 Summary of characteristics
The relevant characteristics from 3.1 0 of IEC 60947-1 :2020 apply, with the following addition.
The characteristics of the equipment shall be stated in terms of the following as applicable:
– type of equipment (see 5.2);
– rated and limiting values for the main circuit (see 5.3);
– utilization category (see 5.4);
– control circuits (see 5.5);
– auxiliary circuits (see 5.6);
5.2 Type of equipment
The following information shall be stated.
– number of poles;
– kind of current (alternating current or direct current);
– in the case of alternating current, number of phases and rated frequency;
– number of positions of the main contacts (if more than two);
– breaking arrangement for fused devices (single opening or double opening).
5.3 Rated and limiting values for the main circuit
5.3.1 General
Rated values are assigned by the manufacturer. They shall be stated in accordance with 5.3.2
to 5.3.7.4 noting that some of the listed values may not apply.
5.3.2 Rated voltages
5.3.2.1 Rated operational voltage (U e )
Subclause 5.3.1 .1 of IEC 60947-1 :2020 applies.
5.3.2.2 Rated insulation voltage (U i )
Subclause 5.3.1 .2 of IEC 60947-1 :2020 applies.
5.3.2.3 Rated impulse withstand voltage (U imp )
Subclause 5.3.1 .3 of IEC 60947-1 :2020 applies.
5.3.3 Currents
5.3.3.1 General
An equipment is defined by the following currents.
5.3.3.2 Conventional free air thermal current (I th )
Subclause 5.3.2.1 of IEC 60947-1 :2020 applies.
5.3.3.3 Conventional enclosed thermal current (I the )
Subclause 5.3.2.2 of IEC 60947-1 :2020 applies.
5.3.3.4 Rated operational current (I e ) or rated operational power
Subclause 5.3.2.3 of IEC 60947-1 :2020 applies.
5.3.3.5 Rated uninterrupted current (I u )
Subclause 5.3.2.4 of IEC 60947-1 :2020 applies.
5.3.4 Rated frequency
Subclause 5.3.3 of IEC 60947-1 :2020 applies.
5.3.5 Rated duty
5.3.5.1 General
The rated duties considered as normal are as follows.
5.3.5.2 Eight-hour duty
Subclause 5.3.4.1 of IEC 60947-1 :2020 applies.
5.3.5.3 Uninterrupted duty
Subclause 5.3.4.2 of IEC 60947-1 :2020 applies.
5.3.6 Normal load and overload characteristics
5.3.6.1 Ability to withstand motor switching overload currents
See Annex A.
5.3.6.2 Rated making capacity
Subclause 5.3.5.2 of IEC 60947-1 :2020 applies with the following additions.
The rated making capacity is stated by reference to the rated operational voltage and rated operational current and to the utilization category according to Table 4.
Not applicable to AC-20 or DC-20 equipment.
5.3.6.3 Rated breaking capacity
Subclause 5.3.5.3 of IEC 60947-1 :2020 applies with the following additions.
The rated breaking capacity is stated by reference to the rated operational voltage and rated operational current and to the utilization category according to Table 4.IEC 60947-4-3 pdf download.