5400 Series TECSource User’s Manual · Page 31
Determining Temperature Stability
The 5400 has a Stability LED which can be used to determine when the
temperature has reached a predetermined level of stability. Two menu settings
control this evaluation, Tol Time and Tol Temp, both of which can be found in
the Main Sensor menu.
For the instrument to be considered stable, it must be within Tol Temp of the set
point for at least Tol Time seconds. For example, if Tol Temp was set to 0.5°C,
and Tol Time was 5 seconds, you could rewrite the above statement to read: for
the instrument to be considered stable, it must be within 0.5° of the set point for
at least 5 seconds. Once this condition is met, the Stable LED will light. If at any
time the actual temperature goes further away from the set point, the instrument
is no longer, and will not start counting time until the temperature returns to
within Tol Temp of the set point.
Using 0.5°C and 5 seconds as your parameters, consider the following plot. In
this example, temperature as it is cooling down to 25°C with a typical oscillation
around the set point as it stabilizes. The green regions indicate where the
temperature is within the tolerance window of 25°C +/- 0.5°C, but it is only on
the fourth green region that it actually stays within the window for over 5
seconds. It’s not considered to be stable (in tolerance) until the blue region,
which is 5 seconds after it last entered the tolerance window.
24
24.5
25
25.5
26
0 5 10 15 20 25
30
Stable
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