IEC 61439

A low-voltage switchgear and controlgear assembly (ASSEMBLY) is a combination of low-voltage switching devices together with associated equipment (for controlling, measuring, signalling, etc.) complete with all the internal mechanical and electrical interconnections and structural parts. As with every component of an electrical installation, the ASSEMBLY also has to comply with its appropriate standard.

In January 2009 the IEC 61439, the new standard for low- voltage switchgear and control gear Assemblies, was published. This was the aim of an international project group which had been working on a task named "radical restructuring and revision of IEC 60439 series" since 1998. This initiative was introduced by several countries following dissatisfaction with the IEC 60439 series. The purpose was to harmonise and define all general requirements for low-voltage electrical Assemblies.

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).

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. The standard defines the design verified ASSEMBLIES and eliminates completely the categories TTA and PTTA. In order to conform to the standard, type tests have been replaced by a design verification which can be carried out by the three equivalent and alternative methods of 1) testing, 2) comparison/ calculation/measurement or 3) application of design rules/ assessment.

MODUTEC LV modular switchboard enclosure systems have been repeatedly Type Tested as per IEC 61439 Part 1 & 2.

Part 1 is the general rules part and cannot be used alone to specify an ASSEMBLY.

Part 2 defines the specific requirements of power switchgear and control gear ASSEMBLIES (PSC ASSEMBLIES) and must be used with Part 1. This is the only part that has a double role, it covers PSC ASSEMBLIES and any ASSEMBLY which is not covered by any other specific parts.

DESIGN VERIFICATION METHODS

Verification made on a sample of an ASSEMBLY or on parts of ASSEMBLIES to show that design meets the requirements of the relevant ASSEMBLY standard

  • Verification by test :Test made on a sample of an ASSEMBLY or on parts of ASSEMBLIES to verify that the design meets the requirements of the relevant assembly standards.
  • Verification by comparison :Structured comparison of a proposed design of an assembly or parts of an assembly with a reference design verified by test.
  • Verification by assessment :Design verification of strict design rules or calculations applied to a sample of an ASSEMBLY or on parts of ASSEMBLIES to verify that the design meets the requirements of the relevant assembly standards
LIST OF TESTS FOR COMPLETE DESIGN VERIFICATION
  • Construction Requirement:
  • Strength of material and parts
  • Degree of protection of enclosures
  • Clearances
  • Creepage distances
  • Protection against electric shock and integrity of protective circuits
  • Incorporation of switching devices and components
  • Internal electrical circuits and connections
  • Terminals for external conductors
  • Performance Requirement:
  • Di-electric properties
  • Verification of temperature rise
  • Short circuit withstand strength
  • Electromagnetic compatibility
  • Mechanical operations

 

Verification options

No.

Characteristics to be verified

Clauses or
subclauses

Testing

Calculation

Design
Rules

1

Strength of materials and parts:
Resistance to corrosion
Properties of insulating materials:
Thermal stability
Resistance of insulating materials to abnormal
heat and fire due to internal electric effects
Resistance to ultraviolet (UV) radiation
Lifting
Mechanical impact
Marking

10.2
10.2.2
10.2.3
10.2.3.1
10.2.3.2

10.2.4
10.2.5
10.2.6
10.2.7


YES

YES
YES

YES
YES
YES
YES


NO

NO
NO

NO
NO
NO
NO


NO

NO
YES

YES
NO
NO
NO

2

Degree of protection of the enclosures

10.3

YES

NO

YES

3

Clearances

10.4

YES

NO

NO

4

Creepage distances

10.4

YES

NO

NO

5

Protection against electric shock and integrity
of protective circuits:
Effective continuity between the exposed conductive
parts of the assembly and the protective circuit
Short-circuit withstand strength of the protective
circuit

10.5

10.5.2

10.5.3



YES

YES



NO

YES



NO

NO

6

Incorporation of switching devices and components

10.6

NO

NO

YES

7

Internal electrical circuits and connections

10.7

NO

NO

YES

8

Terminals for external conductors

10.8

NO

NO

YES

9

Dielectric properties:
Power-frequency withstand voltage
Impulse withstand voltage

10.9
10.9.2
10.9.3


YES
YES


NO
NO


NO
YES

10

Temperature-rise limits

10.10

YES

YES

YES

11

Short-circuit withstand strength

10.11

YES

YES

NO

12

Electromagnetic compatibility (EMC)

10.12

YES

NO

YES

13

Mechanical operation

10.13

YES

NO

NO