PRINT VERSION: IEC 61439 Verification Methods

IEC 61439 Verification Methods

The (relatively new) switchgear and control gear standard, IEC 61439 'Low-voltage switchgear and controlgear assemblies' , ensures compliance to the standard by a series of design and routine verifications.

Design Verifications

The standard has three methods which can be used to verify the design characteristics of an assembly will meet the standard. These are verification by test, verification by calculation and verification by the use of design rules.

The following table (table D.1 from Annex D of the standard, IEC:2011) summarizes each characteristic and the allowable options for design verification:

			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

Routine Verification

Routine verification is carried out the detect faults in workmanship and the correct functioning of the panel. The standard (IEC:2011) list the following:

Construction (see 11.2 to 11.8)
1. degree of protection of enclosures
2. clearances and creepage distances
3. protection against electric shock and integrity of protective circuits
4. incorporation of built-in components
5. internal electrical circuits and connections
6. terminals for external conductors
7. mechanical operation
Performance (see 11.9 to 11.10)
1. dielectric properties
2. wiring, operational performance and function

Original and Assembly Manufacturer

IEC 61439 Verification, Courtesy ABB The standard also tries to explain the differing roles of the original panel manufacturer and a assembly manufacturer. The original manufacturer is the party who initially carries out the panel design and arranges for the necessary design verifications to be performed. The assembly manufacturer is the party who finally builds the panel to the customers requirements and delivers it. The image shows the relationship between the parties and who performs the verification.

Note: if an assembly manufacturer incorporates his own arrangements, he is then deemed to be the original manufacturer by the standard.

In addition to this post, you may also be interested in my post on 'Forms of Internal Separation' according to the standard:

Switchboard - Forms of Internal Separation