Last week I met Jean-Paul Lionet, a member of IEC technical committee who participates to the evolution of Low Voltage Switchgear & Control Gear Assemblies standards. Below is the summary he prepared for me. Don’t hesitate to add your comments or questions !
The IEC 60439-X standards cover all Low Voltage switchgear and controlgear assemblies, i.e. all kind of switchboards and busbar trunking systems. Intended to ensure safety and power availability, they have a long track record of well proven and widely recognized tools, both for design and verification rules and as a reference for certification.
They are now evolving towards a new IEC 61439-X series, aiming to better cover all Assemblies and ensure that the specified performances are achieved.
The main changes may be summarized as follows :
1 – Recognition is made of the evolution of the organization of the industry, between Original Manufacturer and Assembly Manufacturer :
- The conditions for Assembly Manufacturers to benefit from the design verifications made by the Original Manufacturer are stated.
2 – Rules for comparison of a variant with a tested design have been detailed :
- The concepts of TTA (type tested Assembly) and PTTA (Partially Type Tested Assembly), which have been frequently abused and misused, have left the floor to a unified verification approach
3 – Many safety or power availability related requirements have been clarified or reinforced :
- Clarification of the requirements regarding temperature rise, including the rated diversity factor
- Calculations based on safety margins as a means of exemption from temperature rise tests for low-power switchboards
- Increased protection against transient overvoltages
esp. application of higher clearances as a means of exemption from the impulse withstand test
- Better definition of the representative test samples
- Recognition of insulation of live parts and integral housing of the devices as means of meeting internal separation
- Increased mechanical endurance
- A lifting test
- Increased protection against environmental conditions (ingress of water, mechanical impact, resistance to corrosion, resistance to UV for outdoor applications).
4 – These changes and merely editorial choices have resulted in a new structure and a new numbering of the series : the IEC 60439-1 has been split into IEC 61439-1 “general rules” for LV switchgear and controlger assemblies and IEC 61439-2 specific to “Power switchgear and controlgear assemblies”. Parts 2 to 5 of the current series will be aligned on the new IEC 61439-1 by 2011-2012.
IEC 61439-1 and -2 have been published in January 2009.
Each country will apply a transitional period according to its own rules.
In Europe, EN 61439-1 and EN 61439-2 will be published as national standards around mid 2009;
EN 60439-1 will remain valid until 2012, to give time to the manufacturers that might need it to modify their design, to carry out extra testing, and to get 3rd party approval.
A revision of this newly published standard has already been opened.
Schneider Electric will take this opportunity to go on pushing towards more user oriented standards, esp. through an improved Annex C intended to make it easier to specify an assembly.
Member of the IEC SC 17D (Maintenance Teams in charge of the IEC 60439 and IEC 61439 standards)
To obtain the new standard, refer to the IEC website