Verifying Temperature; Figure 1-16 Connections For Model 7700 Thermocouple Temperature Verification - Keithley 2750 Service Manual

Model 2750 Multimeter/Switch System Service Manual

Verifying temperature

Thermocouple, thermistor, and RTD temperature readings are derived from DC volts and
resistance measurements respectively. For that reason, it is not necessary to independently
verify the accuracy of temperature measurements. As long as the DC volts and resistance
functions meet or exceed specifications, temperature function accuracy is automatically
verified. However, temperature verification procedures are provided below for those who
wish to separately verify temperature accuracy.
Thermocouple temperature
1. Connect the DC voltage calibrator output terminals and ice point reference to the
Model 7700 CH1 H and L INPUT terminals using low-thermal shielded connec-
tions, as shown in
Figure 1-16
Connections for Model 7700 thermocouple temperature verification
CH1
CH5
CH3 CH4
INPUT SENSE CH1 CH2
H L H L H L H L
H L H L H L H L
H L H L H L H L H L H L
CH21 CH22 CH11 CH12 CH13 CH14 CH15 CH16
Model 7700
Figure 1-16.
Thermocouple Wire
CH6
CH7 CH8 CH9 CH10
H L H L H L H L
INPUT
(V, 2 WIRE)
SENSE
(OHMS, 4 WIRE)
H L H L H L H L
CH17 CH18 CH19 CH20
H L H L
Make HI and LO
Connections
in Ice Bath
Performance Verification
Twisted
Calibrator (Output DC Voltage)
Output
HI
Output
LO
Low Thermal
Copper Connection
Notes: This setup and reading limits
table does not include errors
from ice point, thermocouple
wire, and connections.
HI and LO connections from
the calibrator and Model 7700
must be electrically isolated
Ice Bath
from each other.
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