For more than three decades, the design and testing of switchgear and controlgear  assemblies has been governed by IEC 60439-1. In 1999, the IEC started a thorough overhaul and full restructuring of this series of standards within the SC17D/MT11 committee. In January this year, parts 1 and 2 of IEC 61439 were published. certification body Kema looks at the new standards' progress

Kema's project manager for industrial components, Henk Kormelink, explains: "The first thing to note is, although the new IEC standards already apply in many parts of the world, they are still awaiting European ratification. Furthermore, in the current transitional period, the choice whether to apply the old or new versions rests with switchgear customers. Eventually, of course, the new standard will prevail".

Kema is thoroughly familiar with the requirements of the new standard. Kormelink is a member of the IEC SC 17D MT11 committee, which is responsible for restructuring the IEC 60439 series. In this way the company contributes to the improvement of the standard by bringing in its experience as a test and certification body and its familiarity with the operations of equipment manufacturers. In fact, he is one of the few representatives of test and certification bodies on the committee and is thoroughly familiar with the requirements of switchgear manufacturers.

The old standard, IEC 60439-1 (Low-voltage switchgear and controlgear assemblies - Part 1: Type-tested (TTA) and partially type-tested (PTTA) assemblies), covered the design and testing of a wide range of equipment. This standard put the emphasis on testing of TTA assemblies, which led to difficulties when revising designs or substituting components. How should a PTTA assembly be verified? This resulted in a situation in which many PTTA systems in the market did not fully comply with the standard. The old situation made it particularly difficult to apply the standard to variants of type-tested assemblies. To prove compliance with the old standard for partially type-tested assemblies was difficult, or at least not very clear.

The new standard provides clear rules for dealing with design variants and component substitutions and can therefore provide end-users with greater certainty that their equipment meets the requirements. Kema is working with a number of large customers to recertify existing products to the new standard and to adopt it in new projects.

Wider scope
The new IEC 61439 standard has a different structure, in that Part 1 includes the general requirements, while Parts 2 - 6 address specific types of equipment. Now this structure is aligned with the IEC 60947 series of standards. Under the new standard, the TTA and PTTA definitions have been removed and now tests can be combined with calculations or design rules to demonstrate that equipment meets the requirements. This is the most important change in the new standard. As a result, the standard now specifies how some changes can be made to equipment without requiring new type tests. This can clearly save a great deal of time and money and is particularly relevant to modular switchgear. More assemblies now meet the requirements and the old partially type-tested assemblies in particular are now covered much more effectively.
The two new standards published so far are:
- IEC 61439-1, General rules (Part 1)
- IEC 61439-2, Power switchgear and controlgear assemblies (Part 2).
The following parts will be published in 2010 to 2011: 
- 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

Until these other parts have been published, the older standard, IEC 60439 will remain in force for the design of such assemblies.

Moving from the old to the new standard
Manufacturers should consider how best to implement the new standards in their design and test workflow. In consultation with the test and certification body they use, it may be possible to re-use test data obtained for the old standard for verification of designs under the new standard. This will reduce the costs of introducing the new standard.

However, this is more difficult with respect to the temperature rise requirements where re-using old data can lead to lower product ratings. To solve this issue, it may be advantageous to carry out some temperature rise tests in accordance with the new standard. This is an aspect panel builders will need to carefully address and discuss with their test and certification bodies.

The standard is detailed and complex, so getting advice from experts in the field is recommended. In recent months Kema has discussed the consequences of the new standard with our large customers and helped them get started with this process.

Testing reference systems
Under the new regime there is much greater scope for testing a reference system and then using calculations and design rules to prove that systems derived from this reference design also meet the requirements.

Working with a reference system as a basis for other designs is particularly attractive when dealing with many variants of the same systems as it can save significant time and costs. The new standard ensures that the performance of all assemblies can now be more thoroughly verified than before. This can be done by testing, by calculation/measurement or by satisfying design rules. Verification covers parameters such as the circuit rating, impulse rating, short-circuit rating, diversity and temperature rise

Special requirements in the Middle East
The speed with which the new standards are adopted will to some extent depend on the demand from the market. In Kema's experience, customers in the Middle East are already requesting that their products be certified to the new standard. The company is particularly familiar with this market and its requirements. In fact, they can carry out tests at non-standard temperatures such as 50°C, which is a requirement of some customers in this region.

Comprehensive service
Kema's positioning is that it can cover the whole range from low voltage to high voltage testing and has extensive in-house test facilities. Any low-voltage tests that are carried out in external laboratories are always witnessed by one of its experts. Depending on the desired degree of risk reduction manufacturers require, they can choose appropriate measures that correspond to an acceptable safety level. This approach can be applied from a simple IP test right up to comprehensive panel certification schemes such as Kema-Keur for panels and the Kema World Panel Program. All these factors combined put the company in a strong position to offer a comprehensive service to manufacturers planning to adopt IEC 61439.

Your move
Panel builders must address the issue as to when their customers want to see the new standards applied. They will then have to review their design, test and manufacturing processes and identify the changes that need to be made. Any additional testing will have to be designed, together with the test and certification body.

Furthermore, panel builders will need to update their design process to incorporate the new arrangements for verification based on the new calculations and design rules, and decide how to optimise their business processes to benefit from the new options. Clearly, any type testing should support this new approach effectively. In this way panel builders can continue to offer their customers the best product at the most attractive price, supplied in the shortest possible time.

A big step forward
In essence the publication of the IEC 61439 series is a great step forward, as the standards now fit in better with the demands of both manufacturers and their customers. The new approach means that compliance with the requirements of the standard can be verified more easily for a range of equipment, without requiring excessive testing or leading to inflexibility. Implementing the standards effectively will, of course, require extensive consultation between a manufacturer and its customers, and with the test house and certification body used by the manufacturer.

Click on the PDF below for a breakdown of the Kema Risk Reduction Building