TECHNICAL INFORMATIONS

Essential Guide to Selecting Reliable Low Voltage Switchgear for Optimal Safety

Technical Information

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IEC 61439 series

The IEC 61439 series cover low-voltage switchgear and controlgear assemblies, including those used in connection with the generation, transmission, distribution, and conversion of electrical energy, as well as for controlling equipment consuming electrical energy.

Purpose:

The IEC 61439 series aims to:

  • Standardize rules and requirements for low-voltage switchgear and controlgear assemblies. 
  • Ensure safety and performance of these assemblies.
  • Define the responsibilities of the original manufacturer (who designs the assembly system) and the assembly manufacturer (who is responsible for the final conformity of the switchboard). 

Key Standards:

  • IEC 61439-1: Provides general rules for the IEC 61439 series, including general definitions, service conditions, construction requirements, technical characteristics, and verification requirements. 

 

  • IEC 61439-2: Specifies requirements for low-voltage switchgear and controlgear assemblies for specific applications, such as those in ships, rail vehicles, or domestic applications. 

Verifications

Design Verifications

There are 3 different methods of verification

Testing

Calculation/ measurement

Satisfying design rules

Routine Verifications

It is a checklist to ensure that all of our switchboards are being build in accordance to the IEC 61439 standards. A total of 12 clauses, 10.2- 10.13 have been verified by these methods under the IEC 61439 standard.

No.
Characteristics to be verified
Clauses
1
Strength of material and parts
10.2
2
Degree of protection of enclosures
10.3
3
Clearances and creepage distances
10.4
4
Protection against electric shock and integrity of protective circuits
10.5
5
Incorporation of switching devices and components
10.6
6
Internal electrical circuits and connections
10.7
7
Terminals for external conductors
10.8
8
Dielectric properties
10.9
9
Temperature-rise limits
10.10
10
Short-circuit withstand strength
10.11
11
Electromagnetic compatibility (EMC)
10.12
12
Mechanical operation
10.13

The fundamental change between the old and new standard is the elimination of type-tested assemblies (TTA) and partially type-tested assemblies (PTTA) in favour of the new design verification approach. This new approach was adopted to reflect current market and application requirements through a controlled and consistent approach.

Technical Change

Verification of mechanical
operations
  • Mechanical operating cycles increased to 200
  • Each circuit requires a defined rating
  • Safety factor of 50%
  • Raised to minimum of 50%

IEC 61439 introduces stricter and more consistent temperature rise requirements, ensuring safer and more reliable switchgear assemblies.

  • IEC 61439 extended and refined testing methodologies to ensure real-world safety and reliability.
  • More flexible verification through Testing, Derivation, or Calculation, but PTTA is no longer allowed.
  • Temperature rise, short-circuit, dielectric, and EMC tests have stricter and clearer requirements.
  • Improved definition of rated current (InA) and performance conditions ensures consistency across designs.
  • Manufacturers must justify derivations with engineering evidence.
  • Physical testing is preferred, especially if significant design variations exist.
  • IEC 61439 eliminates loopholes that existed in IEC 60439, ensuring better safety and performance.
  • ≤ 630A for single compartments
  • ≤1600A for multiple compartments
Verification of mechanical operations
  • Mechanical operating cycles increased to 200
  • Each circuit requires a defined rating
  • Safety factor of 50%
  • Raised to minimum of 50%

IEC 61439 introduces stricter and more consistent temperature rise requirements, ensuring safer and more reliable switchgear assemblies.

  • IEC 61439 extended and refined testing methodologies to ensure real-world safety and reliability.
  • More flexible verification through Testing, Derivation, or Calculation, but PTTA is no longer allowed.
  • Temperature rise, short-circuit, dielectric, and EMC tests have stricter and clearer requirements.
  • Improved definition of rated current (InA) and performance conditions ensures consistency across designs.
  • Manufacturers must justify derivations with engineering evidence.
  • Physical testing is preferred, especially if significant design variations exist.
  • IEC 61439 eliminates loopholes that existed in IEC 60439, ensuring better safety and performance.
  • ≤ 630A for single compartments
  • ≤1600A for multiple compartments

Standard

Other IEC Standard

IEC 529 outlines an international classification system for the sealing effectiveness of enclosures of electrical equipment against the intrusion into the equipment of foreign bodies (i.e., tools, dust, fingers) and moisture. This classification system utilises the letters ‘IP’ (Ingress Protection) followed by two digits. The first digit of the IP code indicates the degree that equipment is protected against solid bodies intruding into an enclosure. The second digit indicates the degree of protection of the equipment inside the enclosure against the harmful entry of various forms of moisture (e.g., dripping, spraying, submersion, etc.). Fuji SMBE’s M-Cube switchgear is designed specifically to IP 44.

A higher IP rating would result in poor ventilation of the switchboard and result in poor performance and de-rating of the components.
Therefore, the M-Cube is designed to IP 44 so as to balance safety and performance of the switchboard.

IEC Series​

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