Keithley 2001 Operator's Manual page 81

Translating SPRTD coefficients
Subrange #1: 13.8033K - 273.16K
Subrange #2: 24.5561K - 273.16K
Subrange #3: 54.3584K - 273.16K
Subrange #4: 83.8058K - 273.16K
Subrange #5: 234.3156K - 302.9146K
Subrange #6: 273.15K - 1234.93K
Subrange #7: 273.15K - 933.473K
Subrange #8: 273.15K - 692.677K
Subrange #9: 273.15K - 505.078K
Subrange #10: 273.15K - 429.7485K
Subrange #11: 273.15K - 302.9146K
An SPRTD as supplied from the manufacturer will come
with a certificate of calibration that lists the calibration
constants and the temperature range supported. In all cases
except subranges #4 and #7, translation of the supplied
coefficients to Model 2001 values will be required. In most
cases, this translation is done simply entering the A value
(for example) supplied with the SPRTD into the A4 position
(temperatures less than 0°C) or A7 value (temperatures
above 0°C) required by the Model 2001. The same procedure
is used for translating the B and, where applicable, C
constants.
Table 3-24 should be helpful in translating SPRTD
coefficients to Model 2001 SPRTD coefficients. The Model
2001 supports SPRTD temperatures between 83.805K and
933.473K. For any of the subranges below, only
temperatures within the range from 83.805K to 933.47K will
be measured.
Measurement Example: Suppose you are using an SPRTD
that has been calibrated for subrange #2 above, in which case
the RTD is calibrated for measurements between 24.5561
and 273.16K. The Model 2001, however, supports only
SPRTD temperatures down to 83.805K, so temperatures
below this value will be reported as an overflow even though
the SPRTD is capable of measuring lower. The calibration
certificate lists A2, B2, C1, C2, and C3 as the calibration
coefficients. You can set up the Model 2001 for this
measurement as follows:
1. Set the temperature sensor type to be FRTD (4-wire
measurement) from the CONFIG/TEMP/SENSOR/
TYPE menu.
2. Choose the SPRTD RTD type using the CONFIG/
TEMP/SENSOR/TYPE/FRTD/SPRTD menu.
2001-900-01 Rev. K/ August 2010
Not applicable
A2 to A4, B2 to B4
A3 to A4, B3 to B4
No substitution needed
A5 to A4, A5 to A7, B5 to B4
B5 to B7, Set C7 = 0. A5 value entered for both A4 and A7;
B5 value entered for both B4 and B7
Not applicable
No substitution needed
A8 to A7, B8 to B7, Set C7 = 0
A9 to A7, B9 to B7, Set C7 = 0
A10 to A7, B10 to B7, Set C7 = 0
A11 to A7, Set B7 = 0, C7 = 0
3. From the SPRTD COEFFICIENTS menu, set the RTD
0°C resistance value and the following coefficients:
• Set the Model 2001 A4 coefficient to the RTD
certificate A2 value.
• Set the Model 2001 B4 coefficient to the RTD
certificate B2 value.
Note that the A7, B7, and C7 values will not be used for this
sensor.
4. Switch to the temperature function, and begin taking
readings.
Front Panel Operation
3-49