BEKA BA377E-SS, Manual

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Some Zener barriers and galvanic isolators are
certified for mounting within a protective enclosure
located in Zone 2 which may permit them to be
mounted in the same Ex e enclosure as the
BA377E-SS Timer or Clock. Zener barriers and
galvanic isolators are not permitted in Ex e
enclosures located in Zone 1.
The Timer or Clock terminals, the wiring to the Timer
or Clock and the intrinsically safe interface, if
mounted within the enclosure, should be segregated
from all other non-intrinsically safe wiring and
equipment within the panel enclosure as required by
EN 60079-11
Equipment protected by intrinsic safety
and EN 60079-14 Electrical installations design,
selection and erection .
The Ex e panel enclosure should be fitted with a
warning label saying 'Do not open when non-
intrinsically safe circuits are energised', alternatively
all bare live non-intrinsically safe parts within the
panel enclosure should have an IP30 cover carrying
a warning label 'Do not open when energised'.
The power dissipation within an BA377E-SS fitted
with operational alarms and a backlight is normally
about 350mW. In the very unlikely event that all
three circuits fail to the worst case condition at the
same time, the total power dissipation rises to 2.5W
which could raise the internal temperature of a small
thermally well insulated panel enclosure.
3.3.2 Installation in Ex p panel enclosure within
Zone 1 or Zone 2.
Installation of a BA377E-SS Timer or Clock in an
Ex p IIC Gb or Ex p IIC Gc pressurised panel
enclosure does not invalidate the Ex p panel's
impact and ingress protection as the front of the
Timer or Clock complies with Ex p impact and
ingress requirements. Although mounted in an Ex p
panel enclosure, the BA377E-SS remains Group II
Category 1G Ex ia IIC T5 Ga intrinsically safe
apparatus and must therefore be powered via a
Zener barrier or galvanic isolator as described in
section 3.1 and 3.2 of this manual.
When installed in an Ex p panel enclosure the four
vents at the rear of the Timer or Clock which are
shown in Fig 13 should not be obstructed.
Zener barriers and galvanic isolators may be
installed in the same Ex p enclosure as the
BA377E-SS. All may be mounted in an Ex px
enclosure installed in Zones 1 or 2, or in an Ex pz
enclosure installed in Zone 2, both of which have a
non-hazardous interior. Some Zener barriers and
galvanic isolators may have certification permitting
installation within an Ex py enclosure which has a
Zone 2 interior.
The Timer or Clock's terminals, the wiring to the
Timer or Clock and the intrinsically safe interface, if
mounted within the enclosure, should be segregated
from all other non-intrinsically safe wiring and
equipment within the panel enclosure as required by
EN 60079-11
Equipment protected by intrinsic safety
and EN 60079-14 Electrical installations design,
selection and erection .
If live maintenance is anticipated, it is recommended
that the Ex p panel enclosure should be fitted with a
warning label saying 'Do not open when non-
intrinsically safe circuits are energised', alternatively
all bare live non-intrinsically safe parts within the
panel enclosure should have an IP30 cover carrying
a warning label 'Do not open when energised'.
Fig 10 Typical installation in Ex p panel enclosure