Question 1

What does ABB MNS type-tested to IEC 61439-2 mean for panel builders?

Accepted Answer

When ABB supplies MNS as a type-tested assembly under IEC 61439-2, it means the specific enclosure, busbar arrangement and functional units have been factory tested for dielectric strength, temperature rise, and short-circuit withstand as a representative construction. Panel builders can use the type-test report to reduce the scope of additional testing during assembly verification—provided the final assembly matches the configurations and rated currents covered by the report. Always confirm the type-test report limits (rated current, short-circuit rating in kA, forms of separation such as Form 4b) and apply the partial or full verification procedures from IEC 61439-1/2 when modifying or extending a type-tested design.

Question 2

How do I size Tmax XT or Emax 2 breakers for an IEC 61439 main distribution board?

Accepted Answer

Sizing Tmax XT or Emax 2 breakers requires evaluating continuous load currents, fault level (prospective short-circuit current), selectivity, and coordination with protection curve requirements. Both breakers comply with IEC 60947-2; Emax 2 provides higher short-time withstand and advanced electronic trip settings for main incomers. Verify the panel’s rated current and busbar capability (for example 1600 A, 2500 A, 4000 A bus options) and ensure the breaker’s rated short-circuit making and breaking capacities meet or exceed the assembly short-circuit rating per IEC 61439 design verification. Use manufacturer coordination guides and time-current characteristic data to set long-time, short-time, and instantaneous trips for selective protection.

Question 3

Which forms of separation are supported by ABB MNS and what do they mean?

Accepted Answer

ABB MNS platforms are designed to achieve internal separation schemes up to Form 4b as defined in IEC 61439-1: Form 1 (no separation), Form 2 (separation between functional units), Form 3 (separation of busbars, functional units and terminals), and Form 4 (internal functional unit withdrawal with separate busbar and cable compartments). Form 4b indicates full separation where a withdrawn unit cannot expose live parts—critical for safe withdrawal of MCC units. Choosing the correct form affects maintenance accessibility, personnel safety, and how the assembly is type-tested or design-verified.

Question 4

Can ABB components be used in hazardous-area IEC 60079 installations?

Accepted Answer

Yes, but use requires careful selection. ABB offers products and solutions suitable for hazardous areas when coupled with appropriate Ex-certified components or installed within certified Ex enclosures per IEC/EN 60079. For example, motor control centers intended for gas or dust atmospheres must be configured with Ex-rated instruments, cable entries and gland arrangements, and be evaluated against IEC 60079 series (explosion protection). Always confirm the specific product variant carries the required ATEX/IECEx/NEC/CSA certification for the intended zone/class and follow site-specific installation rules.

Question 5

What short-circuit ratings can I expect from ABB MNS and Emax 2 assemblies?

Accepted Answer

Short-circuit rating depends on configuration: busbar cross-section, enclosure design and breaker capabilities. ABB MNS assemblies are type-tested or design-verified for short-circuit withstand levels commonly starting at 50 kA up to 100 kA (1 s or 3 s) in verified configurations. Emax 2 breakers have high breaking and making capacities, suitable for main incomers where higher fault levels exist. Exact kA values must be confirmed from ABB type-test certificates and breaker datasheets—designers must ensure the panel’s rated short-circuit capacity equals or exceeds the site prospective fault level per IEC 61439 verification.

Question 6

How do AF contactors integrate into MCC buckets for IEC 61439 motor control?

Accepted Answer

ABB AF contactors (IEC 60947-4-1 compliant) are used as the primary motor switching element inside MCC buckets. Integration best practices include: using shrouded power connections, segregation of control wiring, mating dimensions compatible with MNS withdrawable carriers, and coordinated thermal and short-circuit protection (motor overload relays and upstream breakers). Ensure the contactor’s AC-3 motor ratings match motor starting currents and that coordination with protective devices meets selectivity and fault-clearing objectives defined in the panel’s IEC 61439 verification.

Question 7

What is the difference between type-tested and partially type-tested ABB assemblies?

Accepted Answer

A type-tested assembly is a representative design tested in the factory against the full set of IEC 61439 requirements; the test report can be applied to identical assemblies. A partially type-tested assembly means some tests were carried out on representative parts while other checks require additional verification (calculation or assembly-level testing) to prove compliance. For modifications beyond the tested design—changes in rating, busbar size, or internal separation—additional verification per IEC 61439-1 (routine and special tests) is required to demonstrate compliance.

Question 8

Where can I obtain ABB type-test reports and support for IEC 61439 compliance?

Accepted Answer

ABB provides type-test certificates, technical manuals, and product datasheets through regional ABB documentation portals and local sales engineering contacts. For project-level verification, request the specific ABB type-test report that lists the scope (rated current, short-circuit rating, form of separation, IP rating). For detailed engineering support—coordination studies, protection settings, and FAT planning—contact ABB local support or an experienced panel builder (such as Patrion engineering) to review applicability of the report to your final assembly and to plan any required supplemental verification per IEC 61439-1/2.

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