TE Technology TC-24-25 - Manual (Page 8)

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secondary thermistor input sensor and the temperature entered as the FIXED SET TEMP value.
This allows the controller to maintain a constant temperature difference between the primary
thermistor temperature and the secondary thermistor.
2.4 Enter the SET TEMP HIGH RANGE and SET TEMP LOW RANGE values. These values are used
to linearly scale the temperature range that you are controlling within to the full range of the
external input. The set limit values must be within the temperature range that controller is capable
of controlling to.
For example, suppose you are using a (0 to 5) VDC external input to control the set temperature.
Suppose further that you enter -20 °C for the SET TEMP LOW RANGE and +100 °C for the SET
TEMP HIGH RANGE. This sets up a linear scale of 5 V per 120 °C, or 0.0417 V/°C. So, to
control to 10 °C, for example, you would set the external input voltage to 1.25 V.
2.5 Click the CONTROL TYPE menu key and select which type is appropriate for your application.
The DEADBAND CONTROL is an on/off control and PID CONTROL is a
proportional/integral/derivative control. COMPUTER CONTROL allows a constant, fixed
percentage of power to be applied to the thermoelectric cooler. Generally, DEADBAND
CONTROL should not be used unless care is taken to prevent the thermoelectric cooler from being
damage by excessive thermal cycling.
2.6 Clicking on the CONTROL MODE menu key permits the selection of either HEAT WP1+ AND
WP2- or HEAT WP2+ AND WP1-. These selections establish the polarity for the heating mode of
the thermoelectric cooler. This selection allows you to reverse the current flow in the thermoelectric
cooler without having to change the wiring.
NOTE: For TE Technology’s standard products, the TE+ (red) wire should be attached to WP2
and the TE- (black) wire should be attached to WP1 as shown in the “Controller Wiring Diagram.”
The CONTROL MODE should then be set to HEAT WP1+ and WP2-.
2.7 The ALARM TYPE menu key permits the selection of available alarm options. NO ALARM
PICKED indicates that no alarm parameters are desired. SET TRACKING ALARMS allows an
alarm to be set with respect to the set temperature. It will move accordingly with a change of the
temperature setting. This option can be used for a high alarm, low alarm, or both settings. FIXED
VALUE ALARMS permits the setting of a fixed, absolute temperature either above or below the set
point temperature or both. COMPUTER CONTROLLED ALARM is not an actual alarm, but
provides for user activation of the alarm relay via the computer software. The “Expansion
Connector Wiring Diagram” shows how customer-supplied LED’s can be installed to signal various
alarm conditions.
2.8 The POWER OUT SHUT DOWN IF ALARM menu key provides two selections. NO SHUT
DOWN IF ALARM will let the controller continue to control to the set temperature. MAIN OUT
SHUTDOWN IF ALARM shuts off power to the cooler when an alarm condition exists.