Alarm Systems
14
Laboratory and Plasma Freezers
Thermo Fisher Scientific
9.3 Installing a Remote
Alarm (Optional)
Remote alarm terminals are located at the rear of the machine compartment.
The terminals are: Common, Open on Fail (Normally Closed), and Close
on Fail (Normally Open).
1.
The remote alarm system has two keyhole slots on the back to hang the
alarm system on the wall. Insert two screws, no longer than a #12
truss-head type and spaced two inches apart, into a wall and mount the
alarm.
2.
Make the following connections:
a. Connect the common terminal on the cabinet switch to the purple
wire on the alarm.
b. Connect the normally closed terminal on the cabinet to the black
(“open on fail”) wire on the alarm. This connection gives an alarm
when the switch contacts open.
3.
Plug the alarm system service cord into an electrical outlet. This alarm is
designed for 115V/60 Hz, 115V/50 Hz, or 100V/50 Hz operation.
Note
: If you want the alarm signal to sound when the switch contacts
close
,
connect the normally open terminal on the cabinet to the red/white (“close
on fail”) wire on the alarm. The purple and red/white wires must be tied
together in this application.
The wiring diagram is attached to the inside of the alarm back cover.
9.4 Alarm Test
Your freezer is equipped with a SureTemp
TM
testing system which
automatically tests the alarm probe and electronics. This may eliminate the
need for other methods of warming or cooling the probe, such as ice baths.
Theory of Operation
During the alarm test, the temperature sensor is artificially heated by a
tiny, built-in thermoelectric heating unit which simulates warm conditions.
The electronic control module notes the sensor temperature changes and the
control panel displays these changes.
While this alarm testing procedure is very accurate and reliable, the
temperature of the refrigerated space does not change during the alarm test.
