BEKA BA627E-SS, Manual, Page: 17 / 18

7. ACCESSORIES
7.1 Scale card
The BA627E-SS Set Point Station has a window on
the right hand side of the display through which the
scale card showing the units represented by the out-
put current such as ºC or mBar can be seen.
New
Set Point Stations are fitted with a scale card show-
ing the units specified when the instrument was
ordered, if the units are not specified when the in-
strument is ordered a blank scale card will be fitted.
A pack of scale cards pre-printed with common units
of measurement is available as an accessory.
These can easily be fitted to the Set Point Station
without opening the instrument enclosure or remov-
ing it from the panel, See section 4.5 of this instruc-
tion manual.
Custom scale cards for applications requiring less
common units of measurement are also available.
7.2 Tag information
New Set Point Stations can be supplied with a tag
number or application information laser etched onto
the rear panel adjacent to the terminals. This tag in-
formation is not visible from the front of the instru-
ment after installation.
7.3 Display backlight
The BA627E-SS Set Point Station can be supplied
with a factory fitted green backlight that may be loop
or separately powered.
When loop powered the backlight produces back-
ground illumination enabling the display to be read at
night or in poor lighting conditions.
No additional
power supply or field wiring are required, but the Set
Point Station’s minimum operating voltage is in-
creased. When separately powered the backlight is
brighter, but additional field wiring is required.
Fig 8 Terminals for optional backlight
7.3.1 Loop powering the backlight
The backlight is loop powered by connecting it in
series with the Set Point Station’s 4/20mA output as
shown in Fig 9, which increases the minimum oper-
ating voltage to 10V.
Fig 9 Loop powered backlight
Providing the increased voltage drop can be toler-
ated, the system design described in sections 3 of
this manual remain valid with the backlight loop
powered.
7.3.2 Separately powering the backlight
The optional backlight may also be powered from a
separate power supply as shown in Fig 10.
Fig 10 Separately powered backlight
When separately powered the backlight draws a
constant current of 22.5mA at or above 9V. Below
this voltage the backlight continues to function but
with reduced brilliance. Powering the backlight from
an adjustable voltage supply allows the backlight bril-
liance to be adjusted which is a useful feature when
the operator’s night vision has to be preserved.
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