1. Wöhner provides online tools and software to help designers and panel builders verify that their electrical control panel designs meet the IEC 61439 standard for low voltage switchgear assemblies. 2. The tools allow users to calculate short circuit withstand capability, current carrying capacity of busbars, and dielectric strength based on design inputs. 3. Adhering to IEC 61439 ensures safety and proper functioning through compliance verified at the design stage rather than through testing later.

1. IEC 61439 STANDARD IN
ELECTRICAL BUSBAR SYSTEMS
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2. Preface
In the Electrical manufacturing industry ‘Standards’ which define clear rules are extremely necessary for safety, proper functioning & to ensure
quality at all levels. All the rules and recommendation under standards have been derived through extensive real world testing which assures
correct or proper functioning of an electrical installation.
Not adhering to standards can result into grave electrical hazard affecting the end user. Following standards ensures safe operation of the
electrical installation for many years.
Introduction
The IEC/EN 61439 is the result of the work of technical committees and subcommittees composed of representatives of the full member national
electrotechnical committees in Europe, each dealing with a particular subject in the entire range of Electrical products and assemblies.
IEC standard 61439 covers low voltage switchgear and control gear assemblies. It is a replacement for the earlier IEC standard 60439 and is now
the industry standard requirement for all low voltage switchgear and control gear panel assemblies. The new standard gives details on the
requirements of products through testing and other verification methods especially at pre design stage.
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3. How does this new standard add value to the OEM, Consultant,
Designer and Panel Builder?
The designer, be it from the consultant, OEM or the Panel builder identifies the needs and constraints for design, installation, operation and up-
gradation of the complete system right at the design stage.
He chooses the correct switch gear, cables, connectors, busbar products and other components as per the specifications that he intends to use in
his final assembly. Before he takes it up for manufacturing, at the design stage itself he needs to be sure that his choice of components are proper
and that when the components are fitted in the control panel or Distribution panel that they follow the IEC 61439 standard.
To ensure this the designer carries out the design verification by various software tools provided by manufacturer which allows the electrical
designer to be sure of his installation at an early stage.
1) The verification of the design by actual testing himself or by third party labs & by the calculation via prescribed tools supplied by the product
manufacturer.
2) Proper documentation of this design verification (e.g. test documentation, calculations) is then made by the prescribed tools provided by the
manufacturer.
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Why was the new standard created?
In the earlier IEC standard 60439, ‘Design verification’ was excluded, and therefore the respective roles of equipment manufacturers and panel
builders were not clearly defined, so responsibility for ensuring compliance was equally difficult to pinpoint. .

4. General information about IEC - 61439
In IEC 61439 three verification methods are recommended
• First by test
• Second by comparisons
• Third with reference to design & by assessment.
This covers Assemblies integrated for Generation, Transmission & Distribution of Electrical Energy and assemblies designed for Electrical equipment
all in the voltage range not exceeding 1000V AC or 1500V DC.
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The panel builder thus is not only responsible for the completed assembly but also responsible for:
• The rating of the switchgear assembly according to the customer requirements.
• The compliance with the design verification of the original manufacturer.
• The declaration of conformity to the customer (Declaration of Conformity)
• The marking and documentation of the assembly
• The performance of the design verification and documentation

5. www.messung-woehner.com
Wöhner has been synonymous with top performance and innovation in technology for over
88 years. With over 100 registered patents, the Wöhner group is well established
worldwide as a competent and reliable partner for energy distribution, control technology
and renewable energies.
Wöhner has made it easier for electrical designers to adopt the new standard through
verification methods by specially designed software tools on their website, which can be
used for saving costs & need for additional testing.
• Short circuit strength: Pre calculated & tested by third party (avoids own testing
requirements)*
• Temperature rise test: Pre calculated & tested by third party (avoids own testing
requirements)
• Current insulation: Creep-age distance and isolation voltage pre-tested according
to standards
• Dielectric strength: By specification in product data sheet ( Flexible Busbar )
*If short circuit values are not taken in to consideration, during electrical fault
there would be a serious fire hazard, harmful to everyone.
Wöhner provides the current carrying capacity of the busbar and short circuit withstand
capability of the system by calculation method with special tools on the website.
Wöhner Busbar System and IEC 61439 standards
Cross Board Classic
60 Classic

6. 1. Tools for achieving IEC 61439
Wöhner provides following free online tools which can be used by designer/planners verify their own design and confer to all the standards under IEC 61439
1) Software for own design verification making the installation IEC complaint
2) Configurator tool to design and achieve the required Short circuit withstanding capability
3) Current carrying capacity of a Busbar & busbar holder with respect to temperature of busbar & enclosure
4) Di-electric strength of the assembly of Busbar in the electrical enclosure
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Wöhner provides special software which
can be accessed under their website menu
“Tools” where designer can fill up the
Verification by comparison with a reference
construction using the checklist under this
tool. And documentation can be made for
final submission to end user conferring to
IEC requirements.
Software for own design
verification making the
installation IEC complaint:

7. 2. Configurator tool to design and achieve the required Short
circuit withstanding capability
A snap shot of configurator tool to
achieve desired level of short circuit
rating;
Wöhner configurator tool can be
used to construct the power
distribution and to achieve and
maintain the desired short circuit
withstanding capability of the system
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8. 3. To measure the Short circuit carrying capacity of a Bus bar system
We can check short circuit strength of a Busbar system by
the design tools provided by Wöhner by the following
simple steps:
The short circuit strength mainly depends on few
parameters like size of the busbar, number of supports and
distance between the busbar supports.
Example:
Using the “design” tools by Wöhner we select the busbar
support in the 60Classic 3P range (01500 Wöhner part
number) busbar size of 20mmx10mm, Decide that we will
be using two numbers of busbar supports and that the
distance between number of supports will be 300 mm by
giving these inputs in the “design” tools we receive the
short circuit strength of 53 KA. (refer screen shot 1)
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9. If we now change the distance
between busbar support from
300 mm to 450 mm by
maintaining all other parameters
same we receive short circuit
strength as 43 KA.
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10. 4. Current carrying capacity of Busbar systems by “design” tools
We can check the “Current carrying
capacity” of the Busbar systems by the
“design” tools provided by Wöhner by
the following simple steps.
The current carrying capacity of Busbar
depends upon the Air temperature
allowable inside the electrical cabinet
and Busbar temperature that the end
User has prescribed as Safe to use.
On the Wöhner website, we need to
select the size of the busbar,
temperature of air permissible in the
electrical panel based upon the user
specifications and allowable temperature
of busbar as desired by the designer and
allowed by the end user. By giving these
inputs we can get the current carrying
capacity of the Busbar.
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For example
if we select busbar to be of the size 20mm x10mm, with a length of 2.4m – (Wöhner item code -01624),
and if we select air temperature of 35°C and busbar temperature of 85°C, we will get the current carrying
capacity 652A. (refer screen shot 3)

11. Now if we keep the size of the busbar and busbar temperature as
constant and change the allowable air temperature from 35°C to
55°C. We will then receive the calculation of the current carrying
capacity of the Busbar to be 508 A.
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With Wöhner products, Usage verification can be done right at the
stage of design, Thus by using the IEC 61439 standard and with the
examples mentioned above the Designer and the OEM manufacturer
and the Electrical panel builder can design very good quality
products. The End User is then provided a system which he can trust
and be ensured about the Safety and reliability,
An actual application photo of the control
panels using Wöhner products.

12. Other features of Wöhner’s unique Busbar solutions:
• Innovative design by Wöhner allows mounting of electrical switch gear
directly on busbars saving expensive real estate in the electrical panel. Wöhner
products guaranty safety & ease of assembly to our customers making the
Assembly time reduce to 1/3rd of the conventional assembly time.
• Copper Busbars are connected to cables & LV switchgear (100A-1000A)
without drilling the Busbars. Well-designed mounting adapters & cable clamps
provide a systematic & compact power distribution panel along with all
features like safety, ease of assembly, ease of maintenance, etc.
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13. Conclusions
“Electrical wiring & design are the most critical part of any electrical installation.
Wöhner Busbar system solution are uniquely designed as per IEC 61439 standard,
and provides for free risk free compliance to standard with best safety, quality &
cost saving.”
Farook Merchant - MD Messung Group (Mega Distributor for Wöhner Products in India.)
“Working with world class standards brings International Quality to control panels
manufactured by our customers. We are able to specify, test & guarantee to our
customer; Critical specifications like Short circuit currents, temperature rise & di-
electric strength as per IEC 61439 standard. This new standard gives details on
the requirements of Wöhner products through testing and other verification
methods. It is intended to make up for some of IEC 60439’s shortcomings.”
Shrikanth Venkateshappa - International Key Account Manager, Wöhner.
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