8. ACCESSORIES
8.1 Scale card
Both models have a window on the right hand side of
the display through which to view a scale card
showing the units of measurement such as
o
C, mBar,
RPM. New indicators are fitted with a scale card
showing the units of measurement specified when the
indicator was ordered, if the units are not specified 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
on-site to the indicator without opening the indicator
enclosure or removing it from the panel, See section
4.5 of this instruction manual.
Custom scale cards for applications requiring less
common units of measurement are also available.
8.2 Tag information
New indicators are supplied with tag or application
information laser etched onto the rear panel adjacent
to the terminals, legend as specified when the
indicator was ordered. This tag information is not
visible from the front of the instrument after
installation.
8.3 Alarms
CAUTION
These alarms outputs should not be used for
critical safety applications such as an emergency
shut down system.
Both models can be supplied with factory fitted dual
solid state, single pole alarm outputs. Each alarm
output may be independently conditioned as a high or
low alarm with a normally open or normally closed
output in the non-alarm condition.
When the 4/20mA current powering the indicator is
removed both alarm outputs will open irrespective of
configuration. The open circuit condition should
therefore be chosen as the alarm condition when
designing an alarm system. Fig 11 illustrates the
conditions available and shows which are fail safe.
When an alarm occurs an alarm annunciator on the
indicator front panel is activated and if required the
numerical display can alternate between the
measured value and the alarm channel identification
‘ALr1’ or ‘ALr2’.
CAUTION
The alarms are activated by the indicator’s
numerical display. Use of the Tare Function
‘tArE’ will change the numerical display, the
alarms will continue to function at the original
displayed value, but this will correspond to a
different input current.
Fig 11 Alarm outputs
Configurable functions for each alarm include
adjustable setpoint, hysteresis, alarm delay and
alarm accept.
8.3.1 Solid state output
Each alarm has a galvanically isolated single pole
solid state switch output which as shown in Fig 12.
The output is polarised and current will only flow in
one direction.
Ron
=
less than 5
Ω
+ 0.7V
Roff
=
greater than 1M
Ω
Fig 12 Equivalent circuit of each alarm output
The solid state output of each alarm may be used
to switch any dc circuit with parameters equal to or
less than:
V
=
30V
I
=
200mA
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