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OPERATION
Introduction to the LDT-5525 Front Panel
06_07 LDT-5525 9
CHAPTER 2
Adjustments
The ADJUST section contains the Adjust knob for entering values, and it contains
the ENBL (adjust enable) switch and indicator. In order to make any adjustment,
the ENBL indicator must be lit. Pressing the ENBL switch toggles the ENBL
indicator on or off.
Display
The display is used to show measurements, output set point, and parameter set
points. Whenever a set point is being displayed, the VIEW SET indicator will be lit.
The DISPLAY switch is used to select the measured current (I TE), temperature,
resistance, or the set point value. The set point type is determined by the MODE
selection. Repeatedly pressing the DISPLAY switch will cycle the display from ITE
to temperature to resistance (with thermistor sensors only) to set point and back to
ITE, and so on.
When in I TE mode, the set point will be TE current.
When in R mode, the set point will be thermistor resistance in KΩ. R mode is not
available if the back panel SENSOR SELECT switch is set to LM335 or AD590.
R mode operation may offer improved set point resolution (over T mode),
depending on the desired temperature set point.
Note: The resistance set point is NOT maintained if the control mode is changed
(e. g. from R mode to T mode). Also, if the SENSOR SELECT switch is moved from 10 µA
to 100 µA while in R mode, the resistance set point will be rounded to match the display
resolution.
When in T mode the set point will be temperature in
o
C.
When the output is off and a measurement is displayed, if the adjust knob is
turned the control mode set point will be displayed for three seconds. If the set
point is adjusted (by turning the adjust knob) the set point timer will be restarted.
Therefore, three seconds after the set point is adjusted the display will return to
the last measurement.
Parameters
The LDT-5525 Temperature Controller allows adjustment of the following
parameters, I LIMIT (TE current limit), T LIMIT (temperature limit) and GAIN
(sensor feedback amplifier gain). In addition, the sensor calibration values may be
entered.
The LDT-5525 will limit the I TE output to the I LIMIT value, regardless of the set
point or control mode.