BEKA BA527C, Manual

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3. Application
3.1 Transmitter loops
BA527C and BA528C indicators may be
connected in series with any 4/20mA current loop
providing the loop can tolerate the additional 1.1V
required to operate the indicator. Fig 2 illustrates a
typical application in which a BA527C or BA528C
indicator is connected in series with a 2-wire
transmitter.
Fig 2 BA527C or BA528C in a transmitter loop
The sum of the maximum voltage drop of all the
components must be less than the minimum power
supply voltage.
Minimum operating voltage of 2-wire Tx 10.0
Maximum voltage drop caused by controller 5.0
Maximum voltage droop caused by indicator 1.1
Maximum voltage drop caused by cables
0.4
______
16.5V
Therefore at 20mA the power supply in this
example must have an output greater than 16.5V
3.2 Remote indication
BA527C and BA528C indicators may be driven
from any 4/20mA signal to provide a remote
indication. Fig 3 shows a typical application in
which the output from a gas analyser drives a
BA527C or BA528C indicator. Again it is necessary
to ensure that the voltage capability of the 4/20mA
output is greater than the sum of the voltage drops
caused by the indicator and the cable resistance
Fig 3 Remote indication
4. Installation
4.1 Location
BA527C and BA528C indicators are housed in
robust aluminium enclosures with polyester front
panels and Noryl bezels. The fronts of both
instruments have IP65 protection, and a gasket
seals the joint between the instrument enclosure
and the panel. The indicators may be installed in
any panel providing the environmental limits shown
in the specification are not exceeded.
Figs 4A and 4B show the overall dimensions of
each instrument and the required panel cut-out
dimensions. To achieve an IP65 seal between the
instrument enclosure and the instrument panel the
smaller tolerance aperture must be used, and the
BA528C must be secured with four mounting clips.