Calibration Procedure - ILX Lightwave LDT-5900 Series User Manual

5
C H A P T E R

Calibration Procedure

1
2
120
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 Procedure
WARMUP
1a Using the multimeter's 4-wire (Kelvin) resistance measurement mode, accurately
measure the resistance of the TE cal and sensor measurement cal resistors. Allow
the measurement to sit undisturbed for at least 1 minute before recording any
readings to allow any heating or excess noise due to handling to dissipate.
1b Connect one end of the calibration/test cable to the output of the instrument to be
calibrated and the other end to the appropriate cal resistors.
1c Go into the Parameter Limits menu and set each limit to its maximum value.
1d Place unit in ITE Mode, set output to 5 A and enable.
1e Allow unit to warm up a minimum of 5 minutes with the output on before proceeding
with calibration.
1f Note: Calculated values for slope and scale factor should be close to 1.00. Offset
values should be close to 0.00.
1g Record the current calibration values by querying each calibration command. This
should be done in case of an error so the previous calibration state can be recovered.
A list of all calibration commands can be found in Figure 3.1 and Table 4.1.
VTE MEASUREMENT CALIBRATION
2a Enable Cal Mode by entering the remote command MODE CAL.
2b Reset the calibration constants to default values of 1.0 for slope and 0.0 for offset by
entering the command CAL:DEFault; CAL: SAVE.
Note: This command sets ALL calibration values to default.
2c Enable ITE Mode by entering the remote command MODE ITE.
2d Set output to -5 A (-4.5 A if 5948 to prevent current limit from enabling) and connect
the DMM (Digital MultiMeter) across the TE Cal resistor to measure voltage. Pay
attention to polarity.
2e Allow one minute for current to stabilize if output has just been enabled.
2f Record the TE voltage as measured by the instrument [(Unit Under Test (UUT)]. A
more accurate method to determine VTE
obtained by querying the instrument via the MEASure:VTE? Command.
Note: Note: Allow a minimum of 2 seconds to elapse between readings to ensure the
instrument has had enough time to perform another round of measurements.
2g Record the actual TE voltage as measured by the DMM (VTE
more accurate to determine VTE
remote querying the DMM.
2h Set output to +5 A (+4.5 A if 5948).
2i Record VTE (preferably via MEASure:VTE?).
UUT2
2j Record VTE .
DMM2
2k Disable output.
is by averaging several readings
UUT1
by averaging several readings obtained by
DMM1
). Again, it is
DMM1