DCA
Page 18
1.
With the hookup described in the Calibration
Setup Section complete, disable AR Option as
described in section titled “Calibrating AR-
equipped DCA’s”. Connect ohmmeter to “UP-
PER” alarm terminals first.
2.
Verify that all pots are set fully counterclockwise,
to 0.00.
NOTE
Steps 3 through 10 apply to high alarms.
Skip to step 11 to calibrate the ten-turn
dials on low alarms.
3.
Apply 0% of appropriate input from application.
Refer to unit’s model number and specifications
listing in table 2.
4.
Turn ZERO pot clockwise until both “UPPER” and
“LOWER” alarms trip.
5.
Apply 100% input to setup.
6.
Turn “UPPER” and “LOWER” pots clockwise to
10.0 setting.
7.
Turn internal FSA pots fully counterclockwise.
High alarm will change state. Disregard low alarm
at this time.
8.
Turn FSA pot for “UPPER” alarm slowly clock-
wise, observing ohmmeter and appropriate front
panel LED.
9.
Set FSA pot (stop turning) at exact point at which
high alarm is tripped. If high alarm is configured
as fail-safe, H1 in the unit model number, verify
that appropriate LED for high alarm is not lit. The
LED for a non-fail-safe high alarm, H2 in the
model number, will be lit.
10. Disconnect ohmmeter, and reconnect it to
“LOWER” alarm section of DCA.
11. With input at 100%, and ohmmeter connected to
“LOWER” alarm section of unit, turn appropriate
“LOWER” FSA pot fully clockwise. Note that low
alarm trips.
12. Turn “LOWER” FSA pot slowly clockwise, observ-
ing ohmmeter and appropriate front panel LED.
13. Set FSA pot (stop turning) at exact point at which
low alarm is tripped.
If low alarm is configured as fail-safe, L1 in the
unit model number, verify that appropriate LED for
low alarm is not lit.
The LED for a non-fail-safe low alarm, L2 in the
model number, will be lit.
14. Alternate the input between its rated 0 and 100%
level, verifying the setting of the unit’s front panel
pots (0.00 at 0% input, 10.00 at 100% input).
Readjust both FSA pots as necessary.
Calibrating DA -equipped Units.
If ordered, the
Deviation Alarm Option allows the user to set alarm
trip points based on the difference between two
inputs. This difference is expressed as a percentage
of total input span, and unit relays are “tripped”
whenever process input varies, more than (high alarm)
or less than (low alarm) the set percentage.
To calibrate DA-equipped DCA’s, a second input
source will be needed. Refer to table 3, and use two
of the appropriate sources as specified.
Refer to figures 2 through 8 as appropriate, to deter-
mine which of the unit terminals is used for the
second, reference input connection.
Finally, refer to the setup shown in figure 9, and add
the connection for the second input source as follows:
“+REF” is used for positive reference input, and the
negative connection for both inputs is common, the “–
IN”.
To calibrate DA-equipped DCA’s:
1.
With setup complete as described in preceding
paragraph, and all pots set fully counterclockwise,
determine percentage of rated input span that is
to serve as difference between reference input
and input #2.
2.
Set reference input to 50% of rated span.
