IEC 61992-4-2015 pdf download.Railway applications – Fixed installations – DC switchgear – Part 4: Outdoor d.c. disconnectors, switch-disconnectors and earthing switches.
4 Service requirements
The equipment covered in this standard is mainly intended for outdoor installations.
The requirements given for outdoor equipment in EN 501 25-2 or in 2.1 .2 of IEC 60694 may be used and IEC 6091 3 may be taken into account. In this standard, the pollution degree PD 4A (see EN 501 24-1 ) is considered as a normal condition.
Where service requirements and environmental class differ from those defined in the above standards, require to be specified or a particular environmental class is required, the purchaser shall state this fact in the tender specification. The supplier shall confirm that the unit is suitable for the service requirements specified.
5 Characteristics of the unit
5.1 Enumeration of the characteristics
The characteristics of the unit and its assigned designations and values (where applicable) are as follows:
– type of unit (5.2);
– rated values (5.3);
– class of use (5.4);
– control circuits (5.5).
5.2 Type of unit
A unit shall be defined by the following details (where applicable):
– whether the unit is a switch disconnector, disconnector, earthing switch or a combination of these types;
– number of poles;
– number of positions (if there are more than two);
– provision of an enclosure;
– degree of protection provided by the enclosure, if any (see IEC 60529).
5.3 Rated values
5.3.1 General
The rated characteristic values shall be specified by the purchaser. Rated insulation voltage values shall be selected from the values indicated in Table 1 of IEC 61 992-1 ; current values should have one of the preferred values in 5.1 .2 of IEC 61 992-1 .
These values shall be confirmed by the manufacturer, who shall indicate the rated values for the type of unit proposed, and shall be complemented with other data.
All these values shall be stipulated in accordance with 5.3.2 to 5.3.4, but it is not necessary to specify all the listed rated values.
5.3.2 Voltages
A unit is defined by the following voltages.
The nominal voltages and the system voltages and limits shall be taken from IEC 60850. The insulation values shall be taken from Table 1 of IEC 61 992-1 :
– nominal voltage U n (see 3.2.1 .1 of IEC 61 992-1 );
– system voltages and limits (see 3.2.1 .2 of IEC 61 992-1 );
– rated voltage U Ne (see 3.2.1 .4 of IEC 61 992-1 );
– rated insulation voltage U Nm (this value shall be equal to or higher than U max ) (see 3.2.1 .3 of IEC 61 992-1 );
– rated impulse withstand voltage U Ni (see 3.2.1 .7 of IEC 61 992-1 );
– power-frequency voltage withstand level (dry and wet) U a (see 3.2.1 .8 of IEC 61 992-1 );
– auxiliary and control supply voltages (see 3.2.1 .5 of IEC 61 992-1 ).
5.3.3 Currents
A unit is defined by the following currents.
The current values shall be selected taking into account 5.1 of IEC 61 992-1 :
– conventional thermal current I th , I the (see 3.2.3 and 3.2.4 of IEC 61 992-1 );
NOTE 1 Earthing switches are not required to be assigned this rating.
– rated service current I Ne (see 3.2.5 of IEC 61 992-1 );
NOTE 2 Earthing switches are not required to be assigned this rating.
– rated breaking and making capacity (see 3.2.1 8 and 3.2.22 of IEC 61 992-1 ):
• switch-disconnectors and those disconnectors for which the manufacturer declares a making capacity, shall be able to make the stated prospective current at a voltage U equal to 1 ,2 × U Ne ;
• a rated breaking capacity requires the unit to be able to interrupt any current of a value lower than or equal to this rated breaking capacity;
– rated short-time withstand current I Ncw (see 3.2.7 of IEC 61 992-1 );
– overload capability: the purchaser shall inform the supplier of the load cycle requirements (see 3.2.5, Note 2 of IEC 61 992-1 ).
5.4 Class of use
Disconnectors shall close and open at no-load except if otherwise declared by the manufacturer.
Switch-disconnectors shall close and open on-load, including highly inductive loads.
Both devices shall have either electrically latched or mechanically latched mechanisms.
The minimum breaking, making and short-time withstand currents of the units shall be at least those given in Table 1 for the appropriate category.IEC 61992-4 pdf download.