Shellab SRI20P - Manual (Page 17)

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OPERATION
T HEORY OF O PERATION
Each SRIP 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 in 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 and cooling the chamber. This
results in precise and highly efficient cooling and heating operations with minimum power use. The
circulating fan provides even air distribution throughout the chamber and assures temperature uniformity
around the unit’s entire shelf space.
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 .