Calibration; Recommended Equipment - ILX Lightwave LDT-5900 Series User Manual

5
C H A P T E R

Calibration

Several calibrations must be performed to fully calibrate the LDT-5948 and LDT-
5980. These calibrations consist of adjustments to the Analog-to-Digital and
Digital-to-Analog Converters for the TE Voltage Sensor, TE Current Sensor,
bipolar TE output current, Temperature Sensor output current and Temperature
Sensor voltage measurement.
Calibrate the unit every 12 months or whenever performance indicates
recalibration is required. Signs that calibration may be required include
differences between set point and measurement display values that exceed the
accuracy specification. Calibrate the unit in a normal laboratory temperature
range, namely 23°C ± 3°C. If possible, calibrate the unit at its intended use
temperature (if this is within the specified operating temperature range of
10 - 40°C.

Recommended Equipment

A digital voltmeter comparable to an Agilent 34401A is required for instrument
calibration. The pertinent specifications are listed below.
Several different resistive loads are required for calibration as shown below:
Sensor Measurement Calibration
Low resistance cabling capable of running at five Amperes continuous duty is
required to connect between the unit's output connector and the TE test load. The
TE cabling should be twisted together as one bundle and the sensor cabling
twisted together in a separate bundle to minimize noise. The "TEC Sense" and
"Sensor Sense" lines must be connected to their corresponding loads at the same
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LDT-5980/ 5948
C A L I B R A T I O N A N D T R O U B L E S H O O T I N G
Ca libra t ion
Note: Turn on and warm up the unit with output enabled at 5 Amps for a minimum of five
minutes prior to calibration.
DC Voltage
Measurement Accuracy
( 0 - 10VDC)
4-wire (Kelvin)
Resistance Measurement
Accuracy ( 0 - 1M )
Input Resistance
(ranges 10V and lower)
TE Measurement / Output
Calibration
+ 0.002%
+ 0.002%
> 10 G
10 , 100 , 1 k , 10 k , and 100 k
resistors, 1%, 1/4 W, 1 PPM temperature
coefficient
1 resistor, 1%, 100W or greater, 25 - 50 PPM
temperature coefficient, adequately heatsunk
(TE output calibration); 6
greater, 25 - 50 PPM temperature coefficient,
adequately heatsunk (RAC calibration)
resistor, 1%, 5W or