Isotech TTI-7-R, Operator'S Handbook Manual

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Operating the TTI-7-R
b) Selecting negative measuring current polarity (-I)
Press for reversed or negative measuring current polarity. The
measurement time is approximately 1.8 seconds per reading for
channels A and B, and 3.6 seconds for Ch1-Ch2 relative
measurement.
c) Selecting average current
Press 9/AVE to select automatically alternated dc measuring current
polarity switching at a rate of approximately O.SHz. Thermal EMF
measurement errors are eliminated by taking the average value of the
forward and reverse polarity readings. The measurement time is
approximately 3.6 seconds per reading for channels A and B, and 7.2
seconds for Ch1-Ch2 relative measurement. The Average current
mode is the power up default condition.
d) Selecting √ 2 current multiplier
This option reduces current through the probes by √ 2 (half-power), to
determine any probe self heating. The best method of using this option
is first to let the sensor reach a steady temperature and note the value.
It may take some time to stabilise.
Press and immediately select the reduced current through
the probe will reduce the heating effect on the probe, and the value
displayed will represent the temperature change due to the reduced
current.
When the reading has stabilised, note the temperature change. Add
twice the temperature change to the original temperature (observing
the sign; the final temperature should be lower than the original
value). The result is the actual temperature with the effect of probe
self heating eliminated.
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