Serial Number; Temperature Conversion - Fluke Hart Scientific 1575 Super-Thermometer User Manual

• Standby current (1590 with 2590 only)
• Three-wire offset
• Sub-range (ITS-90 only)
• Characterization coefficients applicable to conversion type and selected
7.4.3.1

Serial Number

For SERIAL NO. you can enter up to ten characters that consist of digits from
0 to 9, upper case letters from "A" to "Z", "." and "-". To enter a letter, repeat-
edly press the Exp button until the desired letter appears.
7.4.3.2

Temperature Conversion

CONVERSION specifies what algorithm is used to calculate temperature from
the measured resistance of the probe. Options include ITS-90, IPTS-68,
Callendar-Van Dusen (CVD), POLYNOMIAL, and thermistor. You can also
choose to display resistance R(Ω), ITS-90 ratio W(T
overriding the system units (see Section 7.6.1). Each of the conversion options
is explained in more detail below. The probe characterization parameters that
appear below CONVERSION in the edit list will depend on the type of conver-
sion you select.
NOTE: The unit in which a measurement is displayed can be affected by
both the conversion type and the System Units settings. Ratio or ohms set-
tings will override temperature units.
7.4.3.2.1 ITS-90
Most PRTs and SPRTs are characterized according to the International Temper-
ature Scale of 1990 (ITS-90). If you select ITS-90 for CONVERSION, you
must then select one or two sub-ranges then enter the coefficients for the
sub-ranges. You may select both a low temperature sub-range and a high tem-
perature sub-range. At temperatures where the high and low ranges overlap, the
low range takes precedence. If the probe is calibrated for only one range, set
the unused high or low range to NONE. If both sub-ranges are set to NONE the
temperature will be calculated using the ITS-90 reference function.
If the temperature falls outside the selected sub-range or if no sub-ranges are
selected a warning message will appear: "WARNING: SUBRANGE EX-
CEEDED". This indicates that the calibration of the probe does not apply at
this temperature and it may not be accurate. If the 1575/1590 is unable to cal-
culate temperature because the measured resistance is too low or too high or
there is an error with the coefficients ".........." will be displayed indicating the
measurement is out-of-range.
subrange
7 Front Panel Operation
Probe Menu
), or resistance ratio,
90
47