IEC 61439 standard

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The coming into force of the new EN (IEC) 61439 standard has changed the requirements for low-voltage power distribution boards in the European Economic Area. It significantly impacts electrical power distribution in buildings and industrial applications. The entirely restructured standard came into force on June 1, 2010. After the end of the transition period, the IEC 61439 standard replaces the previous IEC 60439 standard.

The low-voltage power distribution boards ensure energy-efficient power distribution

General information[edit]

The new EN (IEC) 61439 series of standards defines clear regulations for low-voltage switchgear and controlgear assemblies. It specifies the safety requirements for the electrical equipment of planners, system engineers, electricians and end users in order to define protection objectives for people and industrial plants with regards to electrical installations.

Grafik Norm en.jpg

A low-voltage switchgear and controlgear assembly is defined as the combination of one or more low-voltage switching devices and associated equipment for control, measuring, signaling, protecting and switching.

Low-voltage switchgear and controlgear assemblies includes: Arc fault detection device (AFDD), circuit breakers, miniature circuit breakers, residual current protective devices, cables, terminals, etc.

The standard applies for power distribution boards, switching and control systems, meter cabinets and distribution cabinets in residential and non-residential buildings, distribution boards for construction sites and power distribution cabinets as well as for controlgear assemblies in special areas.

Scope of the standard[edit]

The IEC 61439 standard consists of three parts:

The new standard ensures the manufacture of a standard-compliant switchgear and controlgear assembly
  • EN (IEC) 61439-0: Guidance to specifying switchgear assemblies
  • EN (IEC) 61439-1: the General requirements applicable for switchgear, power distribution boards, control and switching cabinets and the Product-specific components
  • EN (IEC) 61439-2 to 61439-6: for power controlgear assemblies

In addition to the current state of technology, the standard contains some new terminology, ratings and verifications. As the successor of IEC 60439, the new standard describes operating conditions, design requirements, technical properties and verification options for all types of low-voltage switchgear and controlgear assemblies.[1]

Significant changes to EN 60439[edit]

In 1993 the IEC 60439 standard summarized the various types of power distribution boards for the first time, categorizing them with the terms TTA (type-tested switchgear and controlgear assemblies) and PTTA (partially type-tested switchgear and controlgear assemblies). The new standard IEC 61439 replaces the previous categories TTA and PTTA with the term "low-voltage switchgear and controlgear assembly". Also new is the "design verification", which suspends type-testing and the differentiation between TTA and PTTA.

The standard furthermore introduces the so-called "black box concept", which specifies important issues between the manufacturer of the switchgear and controlgear assembly and its user.

The new standard IEC 61349 clearly defines the responsibilities with regards to switchgear and controlgear assemblies

In contrast with the previous standard, IEC 61439 uniquely describes the areas of responsibility of all parties concerned. DIN EN 61439 differentiates between the obligations of an original manufacturer and those of a "manufacturer of switchgear and controlgear assemblies".

The "original manufacturer" is the company manufacturing a ready-to-use switchgear and controlgear assembly for customer applications. Siemens AG is an example of an "original manufacturer" and is therefore responsible for design verification.

A "manufacturer of switchgear and controlgear assembly" is any certified electrician, who builds a power distribution using switchgear and controlgear assembly from an original manufacturer. That electrician is responsible for the relevant switching system and therefore obligated to provide a design verification for all changes not included in the design verification supplied by the original manufacturer.

A "user" can be a planner or system operator, who purchases, uses or operates the switchgear and controlgear assembly. Users must request certifications of the complete design verification.

The rating factor has been defined in more detail, the requirements with regards to heat development have been more explicitly described and have been adapted to the current state of technology. New requirements from IEC 62208 standard (empty enclosure for switchgear and controlgear assemblies) have been additionally applied.

Black box concept[edit]

The standard IEC 61439 specifies the issues to be clarified between the manufacturer of the switchgear and controlgear assembly and its user. It is seen as a so-called "black box" and contacts the installation environment with four defined interfaces:

The switchgear and controlgear assembly as black box with four areas
  • Power supply
  • Setup and ambient conditions
  • Circuits and loads, as well as
  • Operation and maintenance.

All these are defined by relevantly unique technical characteristics and properties, e.g. the protection type (IP), rated frequency fn, rated insulation voltage Ui or door locking.

From the viewpoint of the manufacturer, the black box includes the switchgear and controlgear assembly equipment with its internal workings, the implementation of the defined interfaces to installations outside the equipment and the user requirements. For the electrician, the advantages of the black box concept are on the one hand a significant simplification of their work, on the other hand optimized safety due to the use of prefabricated power distribution board systems.

Design and Routine verification[edit]

The "design verification" replaces the previous type testing. The original manufacturer provides proof of compliance with the design requirements and with it the basic conformity of the switchgear and controlgear assembly. This requires several individual verifications of the various components, which must be documented in the design verification.

A number of equally valid methods can be used for the verification of the requirements

The original manufacturer has various methods for verification available to him to prove that the design complies with the requirements of the relevant switchgear and controlgear assembly standard.

The "routine verification" is the verification process all switchgear and controlgear assemblies must be subjected to during and after manufacture. It detects faults in materials and workmanship and ascertains proper functioning of the manufactured assembly. The results are documented. The manufacturer of the switchgear and controlgear assembly will only have to provide a documented routine verification, if he creates it in accordance with the provisions of the original manufacturer. If that is not the case and the manufacturer of the switchgear and controlgear assembly installs own modifications, then he will be deemed to be the original manufacturer and has to carry out the design verification as well as the routine verification.

Verification documentation

Design verification

The manufacturer of the switchgear and controlgear assembly is faced with new requirements in terms of the extensive documentation obligations of standard EN 61439-1. This may include the verification of sample switchgear and controlgear assemblies or of parts thereof to show that the design complies with the requirements of the relevant switchgear and controlgear assembly standard. Other requirements may include:

  • Complete and detailed documentation of the design verifications of the original manufacturer
  • Test reports, logs, calculations and records
  • Archiving of documentation: throughout the product lifecycle
  • Check lists for the verification of compliance with all requirements set out by the standard for the planning and implementation of the switchgear and controlgear assembly

A forwarding of the documentation to the manufacturer of the switchgear and controlgear assembly is not required. Only one design verification is required for multiple identical assemblies. Any modification to the original system, however, will provide additional design verifications (the manufacturer becomes the original manufacturer).

The design verification applies to the assembly and the operating behavior of the manufacturer of the switchgear and controlgear assembly, and must comply with the following criteria:

  1. Strength of material and parts
  2. Degrees of protection provided by enclosures
  3. Clearances
  4. Creepage distances
  5. Protection against electric shock and continuity of PE circuits
  6. Internal electric circuits and terminals
  7. Terminal connections for external conductors
  8. Dielectric properties
  9. Temperature rise limits
  10. Short-circuit resistance
  11. Electromagnetic compatibility (EMC)
  12. Mechanical function

Routine verification

The manufacturer of the switchgear and controlgear assembly bears the responsibility of providing complete and exhaustive documentation for a routine verification. It includes the test report including all data used and the necessary calculations and comparisons applied. The resulting documentation must be archived for the duration of the lifecycle of the products.

Standardized technical requirements for all applications and products

The manufacturer of the switchgear and controlgear assembly is required to provide a routine verification with the following content in order to prove the correct function of the finished switchgear and controlgear assembly and to detect any material or manufacturing faults:

  1. Enclosure protection types
  2. Air gaps and creepage distances
  3. Protection against electric shock and integrity of protective conductor circuits
  4. Incorporation of switching devices and components
  5. Internal electric circuits and terminals
  6. Terminals for external conductors
  7. Mechanical function
  8. Dielectric properties
  9. Wiring, operating response and functioning

The various verifications therefore collectively confirm the correct function of the individual components of a controlgear and switchgear assembly.

Itemized verification[edit]

  1. ^ DIN EN (IEC) 61439 Low-voltage switchgear and controlgear assemblies

External links[edit]