New IEC Standard for Low Voltage Switchgear and Control Gear Assemblies Standard.

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.

The main changes may be summarized as follows :

• The conditions for Assembly Manufacturers to benefit from the design verifications made by the Original Manufacturer are stated.
• 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
• 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).

What is the basic differences between the new and the former standard?

• Acknowledgement of the “Assembly systems” manufactured by an “original manufacturer” and put at the disposal of final “Assembly manufacturers”.
• Confirmation and clarification of a number of safety or reliability requirements.

[Information from http://engineering.electrical-equipment.org/]