4.2 Enclosure and partitioning (4/12)
The enclosure and internal partitions of the panels
are of 2 mm thick high quality aluminium-zinc
coated steel sheets. The three high voltage
compartments (busbar compartment A, fused
contactor compartment B and cable connection
compartment C) are equipped with top-mounted
and secured pressure relief flaps. These open in
the case of overpressure due to an internal arc
fault.
The front of the panel is closed off by a pressure
resistant door which is opened with the double
bit key to an angle of 120
˚
. The door is fitted
with a manual closing system secured by screws.
Cable and fused contactor compartments share a
common door. The door is equipped with pressure
resistant inspection windows for viewing the
fused contactor and cable connection/earthing
compartments. Neighbouring panels are
partitioned from one another by the side walls
of each panel and, as a result of the design, an
air cushion remains between these walls when
the panels are joined together.
door screws
(4 in total)
double bit key
The enclosure is completed:
a Above, by top-mounted pressure-relief flaps
which, according to the rated branch conductor
current, are made of sheet steel or expanded
metal, and
b Below, by means of floor mounted sheet steel
cable entry gland plate. The pressure-relief flaps
are secured with steel screws on the front
longitudinal side and on the other longitudinal
side with plastic screws. In the case of internal
overpressure, the plastic screws are the point
of rupture.
Arc fault current limitation in the busbar and
fused contactor compartments can be achieved
by instantaneous incoming breaker release,
initiated by Ith limiter auxiliary switches (4/16)
operated by the pressure wave acting on the
pressure relief flaps.
Arc fault current limitation in the fused contactor
and cable compartments is inherent in rupture
of the current limiting HV fuse.
P A N E L D E S I G N A N D E Q U I P M E N T
11
—
4/3 Feeder unit -
direct-on-line
motor starter with
standard arc duct
and top rear entry.
—
4/4 Operation of
the door screw
—
4/3
—
4/4