BEKA BA474ND, Инструкция по установке и обслуживанию, Страница: 7 / 33

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4.4 4/20mA output - terminals 5 & 6
The BA474ND Indicating Temperature Transmitter is
loop powered via these terminals which have the
following input safety parameters:
Ui = 30V
Ii = 100mA
Pi = 0.5W
When installed in a Zone 2 hazardous area the
transmitter must be powered from a supply with
output safety parameters in normal operation equal to
or less than the above.
4.5 Certification label information
The certification information label is fitted in a recess
on the top outer surface of the enclosure. It shows
details of the ATEX gas and dust certifications plus
BEKA associates name and location. IECEx gas and
dust certification are also included.
The instrument serial number and the year of
manufacture are recorded on a separate label inside
the terminal compartment.
5. ELECTRICAL SYSTEM DESIGN
The BA474ND indicating temperature transmitter
may be used as a Type nA instrument with both the
instrument and the sensor in Zone 2 or, using the
sensor input intrinsic safety approval, the sensor may
be installed in Zone 0 or 1.
BEKA Application Guide AG310 provides
comprehensive information on the design, installation
and maintenance of [Extra low voltage dc] Ex nA
instrumentation. The guide may be downloaded
from the BEKA website.
The transmitter is available with an optional factory
fitted display backlight enabling it to be read at night
or in poor lighting conditions, this increases the
minimum operating voltage of the transmitter.
The operating voltage range between terminals 5 & 6
of the BA474ND transmitter at all currents is:
without backlight 9.0 to 30V
with backlight 15.5 to 30V
5.1 Use as a Type nA instrument
The Type nA certification allows the BA474ND
transmitter and the sensor to be installed in a Zone 2
hazardous area as shown in Fig 2.
There are two requirements when designing a
BA474ND loop:
1. The output voltage of the supply powering
the transmitter loop must be equal to or less
than 30.0V in normal operation.
2. The voltage between terminal 5 & 6 of the
BA474ND at all currents must be between:
9 and 30V without a backlight
15.5 and 30V with a backlight
Fig 2 Typical Type nA BA474ND loop