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6.5 Releasing the gas overpressure
WARNING
Do not access the area behind or alongside the
switchgear when it is energised or being energised
(ENA version).
WARNING
Do not access the gas exhaust duct outlets with
the switchgear energised.
Do not install any apparatus in the gas exhaust
area which has not been provided by ABB.
Do not walk on the switchgear.
The highly unlikely event of an internal arc in a
switchgear generates overpressures in the relative
compartment with consequent outlet of hot gases and
particles of material. This outlet must be suitably
controlled in order to protect people and objects from
any injury or damage.
Evacuation of the gases in the switchgear takes place
in different ways according to the IEC or ENA version
and site installation.
6.5.1. IEC version
In the upper part of the switchgear the standard arc-
proof version features a duct for collecting and
conveying internal arc gases (Figure 76). The duct
ends have been extended so as to safeguard
operators working either on the front of the switchgear
or on the accessible sides. This configuration
complies with IEC 62271-200 Standards, Annex A.
In case of usage gas duct with outlet the duct ends
convey the exhausted gases either towards rooms
accessible to personnel or other apparatus / plants,
this end must be extended so as to convey the gases
externally to a safe area. The duct extensions must be
made using metallic sheet that has to withstand a
minimum pressure of 60 kPa, with a crosssection of at
least the same size as the existing duct section and,
(only if necessary) with curves suitably supported and
of the largest radius possible.
The best solution for preventing deposit of gases and
overpressures inside the installation room is to extend
the duct outside (laterally or upwards). In this case,
pay the outmost attention to the access to the gas
outlet area and protect the outlet (outside) so as to
avoid infiltration of water, dust, animals or other
foreign bodies.
In case of usage gas duct with top chimneys there are
no side exits but the exhausted gases goes out from
the duct through the top chimneys located on the top
part of the gas duct inside the installation room.
Both solutions complies with IEC 62271-200
Standards, Annex A.
Note: In case of need or for special installations, do
not hesitate to contact ABB.
Evacuation of the gases in the switchgear (Figure 76)
takes place as follows.
Internal arc in the busbar compartment (2):
the flaps (3) opens up and the gas is conveyed
into the duct (1)
the gas flows through the duct and comes out of
the external outlets (gas duct solution with outlet)
or comes out through top chimneys (gas duct
solution with top chimneys).
Internal arc in the circuit-breaker and cable
compartment (4):
1. the flap (5) opens up and the gas is conveyed into
the duct (1)
2. the gas flows through the duct and comes out of
the external outlets (gas duct solution with outlet)
or comes out through top chimneys (gas duct
solution with top chimneys).
6.5.2. ENA version
Evacuation of the gases in the switchgear (Figure 77)
takes place as follows.
Internal arc in the busbar compartment (2):
the flaps (1) open up and the gas comes out from
the rear/ upper part of the switchgear
Internal arc in the circuit-breaker and cable
compartment (4):
the flaps (3) open up and the gas comes out from
the rear / lower part of the switchgear
Note: Respect 600 mm of aisle on the rear side
Figure 76: IEC version.
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