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OPERATION
T
O
HEORY OF
PERATION
Heating
When powered, the incubator heats to and maintains a user-selected target set point in the incubation
chamber. The incubator senses the chamber air temperature using a solid-state probe mounted on the
chamber interior wall. When the incubator detects that the chamber temperature has dropped below the
target set point, it pulses power to the heating element inside the chamber heating duct in the chamber
ceiling.
The incubator uses Proportional – Integral – Derivative (PID) control to avoid significantly overshooting
the set point. This means the rate of heating slows as the chamber temperature approaches the target
temperature. If the chamber temperature is above the set point, the incubator uses minimum heating to
control the rate of cooling and avoid dipping below the set point.
Additionally, the PID loops optimize heating rates for the temperature environment around the incubator.
If the incubator is operating in a cool room, it will increase the length of heating pulses to compensate.
Likewise, when operating in a warm room the incubator uses shorter pulses. If the ambient temperature
conditions change significantly, there may be minor over or undershoots as the incubator adapts.
The incubators rely on natural heat radiation for cooling. These units can achieve a low-end temperature
just above the ambient room temperature plus the internal waste heat of the unit.
Air Circulation
When powered the incubator circulates air between the incubation chamber and a heating duct
located immediately above the chamber. This air circulation is required to maintain the chamber
temperature uniformity and stability.
The Over Temperature Limit System (OTL)
The OTL is a user-set, mechanical heating cutoff connected to a hydrostatic sensor probe inside the
incubation chamber. The system operates independently of the main microprocessor temperature
controller and routes power away from the incubator heating elements if the chamber temperature
exceeds the OTL temperature cutoff setting. It will continue doing so as long as the chamber
temperature remains above the OTL setting. This helps safeguard the unit by preventing runaway
heating in the event of electronics failures or a sudden external heat spike.
The OTL must be set by the user in order to function. The manufacturer recommends a setting of
approximately 1°C above the highest temperature set point of your heating application. A red indicator
illuminates when the OTL is rerouting power.
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