DCA
Page 14
Setting Low-Alarm Trip Points.
Remember that the
“UPPER” and “LOWER” labeling on the DCA is for
reference purposes only. The DCA can be ordered
without low alarms, as in a “high/high” configuration.
Dual alarm units can be ordered with either one or
both relays configured as low alarms, and DPDT-
equipped DCA’s may be configured with any combina-
tion of high/low alarms.
Refer to the unit’s model number to determine the
alarm configuration, and perform the following proce-
dure for each installed low alarm.
1.
Check model number to verify correct power
input, and apply 117 or 240 Vac; 24 or 45 Vdc, as
appropriate.
2.
Make sure that ohmmeter in calibration setup is
connected to appropriate -NO or -NC terminals, as
desired.
3.
Apply 100% of application’s input span (current or
voltage, as appropriate) to DCA.
If low alarm is configured as fail-safe, L1 in model
number, verify that appropriate LED for that alarm
is lit. LED for non-fail-safe low alarm, L2 in model
number, will not be lit.
4.
Note ohmmeter reading.
In a low alarm, 100% input is a non-alarm condi-
tion. If connected to
X
NO and COM terminals (
X
= U or L, UPP or LOW; NO = normally open),
Resistance across the terminals in a fail-safe
alarm is
zero
. In a non-fail-safe alarm resis-
tance will be near
infinite
.
If connected to
X
NC and COM terminals, resis-
tance is
infinite
in fail-safe,
zero
in non-fail-safe
alarms.
RELAY
RELAY
FOR SINGLE ALARM
STD DCA SHORT
AROUND THIS DIODE
FOR DUAL ALARM STD
DCA SHORT AROUND
THESE DIODES
PC 2
PC 1
LED’S
Figure 12.
AR Option Diodes on PC1 of the STD DCA
