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Chapter 7
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:
7.3.11
Local Operation I
The following procedure is for calibrating the I
polarities of current.
Calibration
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.
Current Calibration
TE
With the output off, connect a 1 Ω, 50 W resistor and a calibrated
a.
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:
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
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.
constant current source for both
TE
I = V / R
TE
85
soft key. Follow the
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