Keithley 2001 Operator's Manual page 80

Front Panel Operation
1. From the CONFIG TEMPERATURE menu, highlight
SENSOR and press ENTER. The following menu is dis-
played:
TEMP SENSOR TYPE
4-WIRE-RTD RTD THERMOCOUPLE
2. Use the cursor keys to highlight the desired sensor and
press ENTER. For the 4-WIRE-RTD and RTD parame-
ters, the following menu is displayed:
SET RTD TYPE
PT385 PT3916 USER-RTD SPRTD
Choosing THERMOCOUPLE displays the following menu:
THERMOCOUPLE SETUP
THERMOCOUPLE-TYPE REF-JUNCTIONS
This menu has six options for RTD standards.
Five are configured for common RTDs, and the sixth allows
you to enter your own RTD factors:
• PT100 – Selects default parameters for the PT100
standard.
• D100 – Selects default parameters for the D100
standard.
• F100 – Selects default parameters for the F100
standard.
• PT385 – Selects default parameters for the PT385
standard.
• PT3916 – Selects default parameters for the PT3916
standard.
• USER-RTD – Selects user-defined parameters.
When one of the five common standards is selected, the
instrument uses the following defaults:
ype Standard Alpha
T
PT100 ITS-90 0.003850
D100 ITS-90 0.003920
F100 ITS-90 0.003900
PT385 IPTS-68 0.003850
PT3916 IPTS-68 0.003916
If you want to change one or more of these factors, select
USER-RTD, and enter the desired values. The equations
using the factors are shown in
3-48
 at 0°C
Beta Delta
0.10863 1.49990 100
0.10630 1.49710 100
0.11000 1.49589 100
0.11100 1.50700 100
0.11600 1.50594 100
Figure 3-21.
For T < 0°C:

= +
R R 1 AT
T 0
For 0°C < T < 630°C:
=
R R
T 0
Where:
=
A
=
B
=
C
Above 0°C, the equation solves faster by applying:
–
A +
=
T ------------------------------------------------------- -
Below 0°C, it is an iterative solution and it runs slower.
cáÖìêÉ=PJON
Temperature equations
SPRTD: Choosing type SPRTD takes you to the SPRTD
COEFFICIENTS menu, which allows you to program the
following parameters:
R-ZERO: RTD 0°C resistance value
A4: set A4 coefficient
B4: set B4 coefficient
A7: set A7 coefficient
B7: set B7 coefficient
C7: set C7 coefficient
The ITS-90 standard provides two reference equations for
Standard Platinum Resistance Thermometers covering the
temperature range 18.8033K to 1234.93K. A single SPRTD,
however, usually cannot be used to cover the entire range.
The temperature range is therefore broken up into several
subranges. These subranges depend on the calibration points
of the temperature scale and are based on the melting or
triple points of various pure substances. For an exact list of
the elements needed and details on RTD calibration, refer to
NIST Technical Note 1265 "Guidelines For Realizing the
International Temperature Scale of 1990". In each subrange,
the calibration constants required for that range are listed.
2001-900-01 Rev. K/ August 2010
2 3
  
+ +
BT CT T-100
2
 
+ +
1 AT BT

 
 1
+
-------- -
 
100
 10 
–
-4
 10 
–
-8
R
 
2
T
----- -
A - 4B 1 -
 
R
0
2B