Power Distribution and Management

IEC 61439, More than just an upgrade, a whole new approach

IEC standard 61439

IEC 61439 is intended to make it simpler and clearer for panel builders to ensure their low voltage assembly installations are up to standard. It also raises the issue of compliance itself. Why exactly does it matter?

IEC standard 61439 covers low voltage switchgear and control gear assemblies. It is intended to make up for some of IEC 60439’s shortcomings. Chief among these is the type-testing requirement. With so many variations of a particular type of low voltage assembly it is simply not practical to type test them all. And anyway, the categories “type-tested assembly” and “partially type tested assembly” actually fail to cover some assemblies.

What’s new – and so special – about IEC 61439?

IEC 61439 brings substantial change replacing the term and concept of type testing and replacing it with “design verification”.  There are 12 design verification characteristics that come under two headings. Part 1, “General Rules”, covers ALL switchgear and controlgear assemblies. Part 2, “Performance” is product specific. (Parts 3, 4, 5, and 6 will be, too.) Clear and practical, it is aimed at panel builders

Construction

  • Strength of materials and parts
  • Degree of protection of enclosures
  • Clearance and creepage distances
  • Protection against electric shocks and integrity of protective circuits
  • Incorporation of switching devices and components
  • Internal electrical circuits and connections
  • Terminals for external conductors

Performances

  • Dielectric properties
  • Temperature rise
  • Short-circuit withstand
  • Electromagnetic compatibility
  • Mechanical operation

Why is compliance so important?

With 61439, panel builders have objective compliance criteria. It makes it clear when their assemblies comply and when they don’t.

Why, though, is compliance so important? And why does 61439 require such detailed compliance?

The obvious answer is that if you “follow the rules” you will have a higher-quality installation. But, then again, if you don’t abide by all the design verification requirements, it won’t stop your assembly from working.

So what difference do 61439’s detailed compliance requirements really make? To answer that question let’s take an example?

We manufacturers might specify an 8mm phase-to-phase clearance. But you decide for reasons of cost or convenience to use a lower clearance – say, 5mm. So far, so good. No problem. Not yet, anyway.

However, our specifications incorporate parameters like degree of pollution, damp, extreme temperatures rises, etc. They ensure safe, reliable operation that lasts for 30 years in all conditions.

 

When and how do the consequences of non-compliance become clear?

So a substandard assembly’s dielectric strength may not immediately start to show premature wear and tear.  It will do so only after a few years. Or in the event of an extreme incident or accident. So, an assembly with a 5mm clearance that has operated satisfactorily for five years may suddenly undergo dielectric breakdown if a lightning strike, for example, causes overvoltage.

Failure may even occur at a critical time with critical consequences. Which is what happened in 1996 when a fire at Düsseldorf Airport killed 17 people and injured 62 due to substandard PVC insulation. And it took 2 months before activity was back to normal.

But, you may argue, short circuits so seldom happen. That’s true. But what if one does happen in a facility where continuity of service is, literally, vital. “Better late than never” doesn’t work in such cases. It’s always too late.

The consequences of non-compliance with seismic norms only become clear when earthquakes strike. And those consequences are dire.

Find more about IEC 61439 and the importance of compliance.

 


One Response
  1. Rob Swann

    Hi, Its a good article.

    I do think that there remains in the industry too much focus on Design Verification by test (Type Testing).

    There is the additional improvement to the IEC 61439 series, that clarifies the need for Routine Verification (Clause 11), this is where the standard really has its impact: No matter if you are the Assembly Manufacturer or Original Manufacturer, the act of Routine Verification should be performed on every supplied assembly.

    This process, if performed correctly, will give much greater clarity to how the supplied assembly meets the requirements of the standard, including the form of Design Verification performed, whether by Test or by the alternative methods that the standard provides.

    Reply

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