Keithley DMM6500

DMM6500
6½-Digit Multimeter with Scanning Calibration and Adjustment Manual Section 2:
Performance verification
DMM6500-905-01 Rev. E June 2021 2-21
Simulated
temperature
Uncompensated
calibrator source
value (V)
Lower limit Upper limit
–190 °C
–7.659 mV
–190.2 °C
–189.8 °C
0 °C
0.000 mV
–0.2 °C
0.2 °C
750 °C
42.281 mV
749.8 °C
750.2 °C
Simulated RTD temperature verification
Use the following information to verify the performance of the DMM6500. Actual calibrator source
values will vary. RTD verification is based on the calibrator sourcing resistance and the DMM6500
conversion of the resistance measurement to calculated temperature based on the Callendar-Van
Dusen equation.
To verify RTD temperature accuracy, you will:
• Apply accurate resistance from the calibrator to the terminals on the front panel of the DMM6500.
• Verify that the displayed readings are within specified limits.
RTD equations
The temperature versus resistance readings listed in the RTD reference tables are calculated using
the Callendar-Van Dusen equation. There are two equations that are based on different temperature
ranges. There is an equation for the –200 °C to 0 °C range and one for the 0 °C to 850 °C range.
Equation for –200 °C to 0 °C temperature range
R
RTD
= R
0
[1 + AT + BT
2
+ CT
3
(T – 100)]
where:
• R
RTD
is the calculated resistance of the RTD
• R
0
is the known RTD resistance at 0 °C
• T is the temperature in °C
• A = alpha [1 + (delta/100)]
• B = –1 (alpha)(delta)(1E-4)
• C = –1 (alpha)(beta)(1E-8)
The alpha, beta, and delta values are listed in the following table.