Lm335 Sensor Calibration - ILX Lightwave LDT-5500B Series User Manual

LM335 Sensor Calibration

The following procedure is for calibrating the LM335 sensor measurement so that
the temperature measurement will be accurate. This procedure calibrates the
voltage measurement of the LM335. This procedure does not calibrate C1 and
C2. For information on calibrating the LM335 sensor, see Appendix C.
Calibration may be aborted by pressing the OUTPUT switch.
05_11
M A I N T E N A N C E A N D T R O U B L E S H O O T I N G
a Set the SENSOR SELECT switch (back panel) to the LM335 position. Set C1 to 0.00,
C2 to 1.00.
b Connect a precision 4 k metal film resistor and a precision voltmeter in parallel at
the sensor input of the LDT-5500B Series Temperature Controller (pins 7 and 8).
c Enter the sensor calibration mode by pushing the display SELECT and parameter
SET buttons at the same time. After this, the display will indicate sensor reference
voltage in 100's of mV. Wait for three seconds for the measurement to settle. The k
enunciator is used to indicate sensor calibration.
d Press and hold in the ENABLE button and turn the ADJUST knob until the display
indicates the same voltage as shown on the precision voltmeter multiplied by 10. For
example, if the voltage across the resistor is 1.9871 Volts, turn the ADJUST knob
until the display reads 19.87.
e Release the ENABLE button and wait for the 7-segment display to flash off and then
back on. Replace the 4 k resistor with a 10 k metal film resistor. After three
seconds, repeat Step d with the 10 k resistor.

Once the final sensor measurement is entered, the display will go blank. During this
step, the sensor temperature set point calibration is taking place internally. Allow the
instrument to self calibrate. Once completed, the calibration constants will be stored
to non-volatile memory, and the display will return to its previous state.
f After calibration, I LIMIT will be automatically set to 2.00 Amps. Reset the I LIMIT to
the desired value.
Calibration Adjustments
LDT-5500B Series
5
C H A P T E R
39
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