Chapter 7 Calibration 85
7.3.10 RTD Lead Resistance Calibration (Offset Null)
Because the RTD sensor reflects changes in temperature with small changes in
resistance, even a small lead resistance (resistance caused by the wire running
between the TEC module and the RTD sensor) can cause significant temperature
offset. The lead resistance may be taken out of the RTD reading as follows:
a. With the TEC output off, short the sensor wires as close to the RTD
sensor as possible.
b. Go to the single module display by first pressing the
MENU
button,
then the
Modules
soft key, then the TEC module soft key.
c. Press the
Setup
soft key and select the RTD as the Sensor Type.
d. Go to the calibration display by first pressing the
MENU
button, then
the
Config
soft key, then the
Cal
soft key, then the channel to be
calibrated. At the calibration screen, press the
RTD Null
soft key.
Follow the on-screen instructions to complete the calibration. The
calibration can be terminated without affecting the stored constants if
the
Term
soft key is pressed at any point prior to completing the
calibration.
7.3.11 Local Operation I
TE
Current Calibration
The following procedure is for calibrating the I
TE
constant current source for both
polarities of current.
a. With the output off, connect a 1 Ω, 50 W resistor and a calibrated
ammeter in series across the laser output terminals. If an ammeter with
the appropriate current ratings is unavailable, connect a 1 Ω, 50 W
resistor across the laser output terminals and use a calibrated DMM to
measure the voltage across the resistor. Calculate the current in the
following steps by using Ohm's Law:
I = V / R
where V is the measured voltage across the resistor, and R is the
measured load resistance.
b. Go to the calibration display by first pressing the
MENU
button, then
the
Config
soft key, then the
Cal
soft key, then the channel to be
calibrated. At the calibration screen, press the
I
TE
soft key. Follow the
on-screen instructions to complete the calibration. The calibration can
be terminated without affecting the stored constants if the
Term
soft
key is pressed at any point prior to completing the calibration.
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