Omega OS137 - Manual (Page 11)

3.4 Alarm Setting
The unit provides 0-100% alarm setpoint adjustment. Here is an example
of an alarm setting:
• An OS137-3-MA (4/20 mA output), the alarm is to be set at 204°C
(400°F) temperature.
• Connect the alarm output as shown in Fig. 2-2.
• Remove the End Cap to get to the Alarm Switch and the Alarm Adjust
(Fig. 3-2).
• Set the Slide Switch on the main board to the Alarm position (2).
• Measure the analog output, and adjust the Alarm Potentiometer until
the output reads 10.4 mA which is 40% (204°C, 400°F) of the
temperature range -18 to 538°C, (0 to 1000°F)
40 x (20-4)
[10.4mA =
100
+ 4]
• Set the Alarm Slide Switch back to the Real Time position (1).
• If the temperature reading is below the alarm setpoint, the Alarm
Output stays low, otherwise it goes high (Alarm Condition).
• The Alarm Output can drive an external mechanical relay.
Operation 3
6