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B-30
Distribution
Definition of Form 3
Separation of busbars from the functional units and separation of all functional units
from one another.
Separation of the terminals for external conductors from the functional units, but not
from each other.
protection against contact with live parts
reduction in the risk of faults between the functional units (propagation of electrical
arcs, etc.).
The two types of Form 3 separation as defined by IEC 60439-1.
b
b
DD381680
DD381681
Form 3a.
Form 3b.
ì
Form 3a
Terminals for external conductors not separated from busbars.
The functional units are separated from each other and from the busbars, but not the
terminals.
Form 3b
Terminals for external conductors separated from busbars.
The functional units are separated from each other and from the busbars.
The terminals are separated from the busbars, but not from each other.
b
b
Form 3 configuration
Form 2 switchboard with:
b
separation of the functional units from one another
b
separation of the terminals for external conductors
from the functional units.
Prisma Plus offers Form 3b because it provides much better safety than Form 3a,
because the terminals are separated from the busbars.
DD383718
Form 3b partitioning.
Form 3 partitioning
Main distribution