Theory of Operation
Chapter 3: Theory of Operation
Page 3 - 22 Isolette® Infant Incubator (Model C2000) Service Manual
The stand supplies the input power and protective ground to the
controller and incorporates a 15 A circuit breaker and electromagnetic
interference (EMI) filtering components.
The controller provides AC power to the heater and the humidifier.
These outputs are fused in the controller to protect the controller in the
event of a short circuit or electrical overload.
• Maximum heater voltage—264V AC
• Maximum heater current—4.8 A
• Maximum humidifier voltage—264V AC
• Maximum heater current—1.2 A
• Heater/humidifier fuse rating—6.3 A
The controller provides DC power to the following:
• The fan
• The sensor module
• The scale
• The SPO
2
module, if available
• The airflow sensors
• The door switches
These outputs are current-limited in the controller to protect the
controller and the powered device if a circuit shorts or electrically
overloads. These outputs are regulated to ensure the output voltage is
within the voltage specification for the powered device. The
microprocessor feeds and monitors the outputs 1 and 2 into the A/D
converter.
Impeller Movement Detector (IMD) P.C. Board
The Impeller Movement Detector (IMD) P.C. board is positioned so that
magnets pressed into the bottom of the impeller pass directly over a
Hall effect sensor mounted to the IMD P.C. board. The IMD circuit
monitors the Hall effect sensor’s pulse train, produced by the magnets
when the impeller rotates. The speed of the impeller is measured and
compared with the pre-determined maximum and minimum acceptance
limits. If the impeller’s rotational speed is too fast or too slow, an
impeller error signal generates. The IMD circuit also detects if one, two,
or all three magnets are missing or if an old impeller without magnets is
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