TE Technology TC-24-25 - Manual (Page 5)

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3) Deadband control (on/off) with an adjustable hysteresis may also be selected. However, this control
mode is not generally recommended.
4) Differential temperature control is provided when two input sensing thermistors are used. The unit
will control the differential between Input 2 (reference temperature) and Input 1 (actual system
temperature).
A control temperature range of –20 °C to +100 °C is standard when using TE Technology’s standard
thermistor sensor probe for the primary set temperature. Additional external set temperature input types
may be selected. As mentioned above, a second thermistor can be used for differential control (or it
could be used for alarm condition sensing). In addition, the controller could use a remote set temperature
potentiometer, a (0 to 5) VDC signal, or a (0 to 20) mA current loop. These secondary inputs are used to
define and “map” the secondary input to an adjustable temperature range in order to remotely control the
set temperature. All temperatures may be consistently displayed in °C or °F.
Two types of control output modes may be selected. This determines the direction of the current flow
through the thermoelectric module during the heat cycle. This current flow may be from wire-point
WP1+ to wire-point WP2-. Alternatively, this current flow may be reversed from WP2+ to WP1- as
selected in the configuration menu.
Several alarm settings may be selected, some of which provide a 5 VDC output, rated for 25 mA of
current for alarm signaling. The settings can be selected for no alarm function, tracking alarm, and
fixed-value alarm. Alarm set temperature values are entered in the setup menu. The computer-
controlled selection is available for additional embedded controller input/output options. The alarm
setup menu also provides for selection of an alarm latching condition. The alarm sensor may be either
the control temperature sensor or a secondary thermistor sensor.
The various alarms have the ability to determine the status of the output power to the thermoelectric
module or auxiliary heater. Power may be maintained during an alarm condition or the main power may
be shut down.