BEKA BA337E-SS, Руководство пользователя

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3.7 Certification label information
The Rate Totaliser certification information 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, location,
year of manufacture and the instrument serial number.
Non European certification information may also be
included.
BA337E-SS Certification information label
4. SYSTEM DESIGN FOR HAZARDOUS AREAS
4.1 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 BA337E-SS.
Terminals 2, 6 and RS2 of the BA337E-SS Rate
Totalisers are internally connected together. If any of
these terminals are earthed, as shown in Figs 2 & 3,
the other common terminals should only be
connected to the same earth, i.e. the barrier busbar,
or to circuits that have 500V rms insulation to earth.
Any Zener barrier may be used with the
BA337E-SS providing it's certification is for use with
apparatus in the required Zone and gas group, and
it's output parameters do not exceed the input
parameters of the Rate Totaliser terminals to which it
is connected. Only one polarity of Zener barrier i.e.
positive or negative, may be used in a Rate Totaliser
system.
Fig 2 illustrates the basic circuit that is used for all
BA337E-SS installations protected by Zener
barriers. For simplicity, connections for the optional
pulse output, 4/20mA output and alarms are shown
separately in section 10 of this manual.
Fig 2 BA337E-SS used with Zener barriers
Alternatively the pulse source may be located in the
safe area. Fig 3 shows how an additional Zener
barrier is used to transfer the signal to the rate
totaliser in the hazardous area. When more than
one Zener barrier is used in a system all must have
the same polarity, i.e. all positive or all negative
barriers.
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