BEKA BA377E-SS, Manual

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2.8 Certification label information
The BA377E-SS product certification label is fitted in
a recess on the top outer surface of the enclosure. It
shows the ATEX and IECEx certification information
plus BEKA associates name and location and the
instrument serial number. Certification information
from other authorities may also be included.
BA377E-SS Certification information label
3. SYSTEM DESIGN FOR HAZARDOUS
AREAS
3.1 Use with Zener barriers
Zener barriers are the least expensive intrinsically
safe interface between a safe and hazardous area.
However, they require a high integrity earth
connection that may be expensive to install and they
do not provide isolation. When a high integrity earth
connection is not already available, it may be less
expensive and complicated to use galvanic isolators
for the installation of a single BA377E-SS.
Terminals 2, 6 and RS2 of the BA377E-SS are
internally connected together as shown in Fig 15. If
any of these terminals are earthed, as shown in
Figs 1 & 2, the other common terminals should only
be connected to the same earth, i.e. the barrier
busbar, or to circuits that have at least 500V
insulation to earth.
Any Zener barrier certified for the gas group and
Zone in which the BA377E-SS is installed may be
used, providing the output parameters do not exceed
the input parameters of the BA377E-SS terminals to
which it is connected. Only one polarity of Zener
barrier i.e. positive or negative may be used in each
system.
Fig 1 illustrates the basic circuit that is used for all
BA377E-SS Timer installations protected by Zener
barriers. BA377E-SS Clock installations are the
same, except that the input terminals 5 & 6 are not
used. For simplicity the optional control outputs are
described separately in section 3.1.9 of this manual.
Fig 1 BA377E-SS Timer used with Zener barriers
Alternatively the sensor may be located in the safe
area. Fig 2 shows how an additional Zener barrier is
used to transfer signals to the Timer in the
hazardous area.