IEC 60439 : Present standard
- The IEC 60439 standard applies to enclosures for which the rated voltage is under or equal to 1000 V AC, (at frequencies not exceeding 1000 Hz) or 1500 V DC.
- The standard makes a distinction between type-tested assemblies (TTA) and partially type-tested assemblies (PTTA).
- All parts mentioned under standard have equal weightage. Formal hierarchy is not maintained. Each part is a complete entity and can be used on an individual basis
IEC 60439 - 1 Type-tested and partially type-tested assemblies
IEC 60439 – 2 Requirements for busbar trunking systems (busways)
IEC 60439 – 3 Requirements for low-voltage switchgear and controlgear assemblies which are to be installed in locations where unskilled persons have access for their use.
IEC 60439 – 4 Requirements for assemblies for construction sites (ACS)
IEC 60439 – 5 Requirements for assemblies intended to be installed outdoors in public places – Cable distribution cabinets (CDCs) for power distribution in networks
The standard remains valid until 2014 and will be replaced by IEC 61439
IEC 61439 : New Standard
Why this change :
- Over a period market needs for assemblies have changed drastically and new designs have evolved based on different applications. The present standard IEC 60439-1 no longer encompasses many commonly used arrangements.
For example, modular systems are not effectively covered with respect to temperature rise performance.
- It is not practical to fully type test every possible configuration of assembly produced. In some of the cases, type testing is not feasible and hence does not have alternative ways of ensuring an assembly that meets the minimum required safety and performance criteria.
- The methods for proving the design of a 'partially type tested assembly' in accordance with IEC 60439-1 are weak and rely entirely on the capability and integrity of assembly designer.
- There is no standard for assemblies that do not fit within the categories of type tested or partially type tested assemblies.
- It is essential that the Standard shall aligned with safety requirements and safety performance is rigorous, consistent and equally applied to all assemblies.
IEC 61439 :
Purpose : To harmonize and define all general requirements for low-voltage electrical Assemblies.
Scope : The new IEC 61439 standard applies to enclosures for which the rated voltage is under 1000 V AC (at frequencies not exceeding 1000 Hz) or 1500 V DC.
New standard has brought considerable clarity in technical interpretation. The new standard follows the philosophy of IEC 60947 series. Released in Jan 2009
IEC 61439 - 0 Guide for specifying assemblies
IEC 61439 - 1 General rules
IEC 61439 – 2 Power switchgear and controlgear assemblies
IEC 61439 – 3 Distribution boards
IEC 61439 – 4 Assemblies for construction sites
IEC 61439 - 5 Assemblies for power distribution
IEC 61439 - 6 Busbar trunking systems
IEC 61439 - 7 Electric Vehicles
Main Changes in IEC 61439 :
The standard defines the ‘ Design Verified Assemblies ‘ and eliminates completely the categories TTA and PTTA.
Type tests have been replaced by a design verification which can be carried out by the three equivalent and alternative methods i.e. Testing, Calculation / Measurement or Application of design rules.
Technical changes in areas such as:
- Verification of mechanical operations
- Verification of temperature rise
- Rated diversity factor
- Clearance verification
- Neutral cross section
- Addition of few verification test such as
- Verification of resistance to UV radiation for outdoor plastic enclosures
- Verification of corrosion resistance
- Mandatory declaration and confirmation of an impulse rating
- Lifting, mechanical impact and marking
- New terms introduced as ‘ Original manufacturer ‘ and ‘Assembly manufacturer ‘
- Split in product responsibility between the ‘ Original manufacturer ‘ and ‘ Assembly manufacturer ‘