Shellab SRI20PF - Manual (Page 16)

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OPERATION
T HEORY OF O PERATION
Each SRIPF incubator uses a Peltier thermoelectric cooling-and-heating device and an air
circulating fan in conjunction with a Proportional-Integrative-Derivative feedback temperature
controller board to achieve precise control over temperature levels within the incubator chamber.
The temperature sensor located in the air stream senses temperature deviations from the set point.
The PID Controller Board uses feedback from the sensor and error calculation functions to ensure
a high degree of thermal stability
– avoiding overshooting or undershooting the user-selected set
point when heating or cooling the chamber. This results in precise and highly efficient cooling and
heating operations with minimum of power use. The circulating fan provides even air distribution
throughout the chamber and assures temperature uniformity around the unit’s shelf space.
An SRIPF Fly incubator can be set to run in a steady state Manual Mode, or in a programmable
Auto Cycle Mode with day
– night variations in temperature and lighting automatically initiated when
user-selected start times are reached. In Manual Mode the incubator runs constantly in either the
Day Time or Night Time phase, as selected by the user. During Day Time phase operations the
Main Temperature Controller Board compensates for extra heat generated by the LED light bars in
the incubator chamber.
D OOR A LARM
The SRIP incubator is equipped with a magnetic induction door alarm which activates when the
door is open and the sensor components are out of range of one another for more than sixty
seconds (1 minute). When the alarm system is active an audio alarm will sound and the control
panel display will flash. Leaving the door open for extended periods will disrupt temperature
uniformity within the incubator chamber, and may result in significantly increased power use as the
temperature controller board attempts to compensate for the disruption.
A CCESSORY C OMPATIBILITY
Make sure that any accessory equipment you will be using inside an SRIP incubator can safely and
effectively operate within your selected temperature range.
T
HE
O
VER
T
EMPERATURE
L
IMIT
S
YSTEM
The OTL is a backup heating control system that operates independently of the unit’s digital Main
Temperature Controller board. In the event of a failure of the controller board while in its heating
mode, the OTL system prevents runaway heating by depowering the peltier thermal electric heating
and cooling unit.
The OTL will not prevent a rise in heat caused by a failure of the peltier itself.
Note: The OTL system should be tested at least once per year using the Set The Over
Temperature Limit procedure .