Thermo Scientific Precision Premium PR305040G, Operating Manual

Page: 19 / 38

5-2 Precision Premium Oven Thermo Scientific
Section 5
Operation
The 3050 Series controllers feature a deviation alarm which alerts the
operator and and interrupts heater power whenever the actual oven
temperature differs from the set temperature by more than 5°C. The set
limit is built in to the controller and cannot be changed.
• If the actual temperature exceeds the alarm limit, the alarm indicator
LED will light and the display will indicate EEE.
• The reference point for the alarm is the set temperature. Any change in
the set temperature will cause a corresponding shift in the alarm
temperature.
Example: If the set temperature is 150°C, the alarm will trip at 155°C.
If the set temperature is changed to 200°C, the alarm will follow the
set temperature and trip at 205°C.
• Changing the set temperature to a value more than 5°C below the
present oven temperature will trip the alarm. Power is removed from
the heaters when an alarm condition occurs.
Example: First experiment samples were being soaked at 160°C.
Experiment completed and oven reset to 140°C. The oven immediately
goes in to alarm once the set point is reset to 140 from 160. The oven
will stay in alarm until the oven temperature cools down to 144.9°
(140,+5, -0.1).
The 3050 Series controllers permit the operator to select a display offset
Offsets temperature. With a display offset entered, the temperature
displayed will be the actual oven temperature (measured at the control
thermocouple) plus or minus the display offset selected. Functionally, the
offset feature permits the operator to measure and calibrate such that the
display will indicate the temperature at a specific point or zone within the
oven. To enter a display offset, carry out the following steps:
1. Press the MENU, the display will indicate CAL
2. To view the present offset value, press and hold the SET key.
3. To change the display offset, press and hold the SET key. Press
INCREASE or DECREASE until the display indicates the desired
offset.
4. Release the SET key.
5. Press MENU once to return to normal temperature control.
Limit Alarms
Display Offsets