Thermistor Sensor Cal; Ic Sensors; Output And Control Mode - ILX Lightwave LDT-5500B Series User Manual

O P E R A T I O N
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C H A P T E R
Introduction to the LDT-5500B Series Front Panel

THERMISTOR SENSOR CAL

These are the constants of the Steinhart-Hart equation that the user enters to
calibrate the TEC for thermistor temperature conversions. The Steinhart-Hart
equation is used to derive temperature from the non-linear resistance of an NTC
(Negative Temperature Coefficient) thermistor. For information on setting C1, C2,
and C3 for thermistors, see Appendix A. For information on thermistor selection
and sensor current selection, see Appendix B.
The range of values for C1, C2, and C3 are -9.99 to +9.99.
To read C1, C2 or C3, press the parameter SELECT button until it sequences to
CONST. While on the CONST parameter, you can continue to cycle through C1,
C2, and finally C3. The display will indicate which constant is currently selected,
and can be adjusted or viewed by pressing the parameter SET button, and turn
the ADJUST knob until the correct value is displayed.
Appendix A contains an explanation of the Steinhart-Hart equation and a
computer program to determine these values for any thermistor.

IC Sensors

These are the constants entered to calibrate the TEC for AD590 and LM335
temperature conversions.
When a linear sensor device (such as an AD590 or LM335) is used, a linear
equation is used. If a linear sensor's calibration is not known, set C1 = 0.00, C2 =
1.00. For more information on linear sensor calibration, see Appendix C.
Appendix C contains information on sensor calibration constants for AD590 and
LM335 sensors. Since these devices are used over their linear range, the
constants C1 and C2 are used in this case to determine a linear approximation of
the temperature, rather than the Steinhart-Hart non-linear approximation which
applies for thermistors. The appropriate algorithms are automatically implemented
whenever the sensor type is selected via the back panel SENSOR SELECT
switch. However, C1 and C2 must be changed by the user.

Output and Control Mode

The MODE section contains the mode SELECT button, which is used to select the
instrument control mode. Repeatedly pressing the mode SELECT button cycles
through the current (I TE), sensor reference (R), or temperature (T) control
modes. The LED indicators show the selected mode. The MODE section also
contains the OUTPUT button and indicator. The ON indicator is lit whenever the
output is on. Pressing the OUTPUT button enables the output of the instrument as
indicated by the LED indicator. With the output enabled, any thermal load
connected to the instrument will be controlled to the mode respective set point.
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