Segregation Forms; Construction Forma Type - ABB MNS R System Manual

Segregation forms

The MNS R segregation forms are
compliant with the relevant standard
IEC 60439-1 annex D. The purpose
of the segregations is mainly to allow
safety access to the internal parts of
the switchgear to operational person-
nel and to minimize propagation of
any faults it may happen in the circuits
and in the adjacent compartments, to
the benefit of service continuity of the
installation.
Construction forms type
Form 1 No segregation
Form 2a Segregation of the busbars from the functional units; terminals are not separated from the busbars
Form 2b Segregations of the busbars from the functional units; the terminals are separated from the busbars
Form 3a Segregations of the busbars from functional units and between functional units; segregation of the terminals
from the functional units, but not from the busbars; terminals not separated from each other
Form 3b Segregations of the busbars from the functional units and between functional units; segregation of the
terminals from the functional units and from the busbars, but not from each other
Form 4a Segregations of the busbars from the functional units and between functional units; segregation of the
terminals from the functional units and from the busbars; the terminals for external conductors are in the same
compartment as the associated functional unit
Form 4b Segregations of the busbars from the functional units and between functional units; segregation of the
terminals from the functional units and from the busbars; the terminals for external conductors are not in the
same compartment as the associated functional unit
Form 4b, rear side Both main and distribution busbars are metallically segregated, plastic covers are used for cable connections.
10
Construction and functional characteristics
Form 4b, rear side.
Both main and distribution busbars are metallically segregated, plastic covers are used for cable
connections.
ABB SACE