Thermocouple Temperatures Using The Optional Cr10Tcr To Measure The Reference Temperature; Thermocouple Temperatures Using An External Reference Junction; Cr10Tcr Mounted On The Cr10 Wiring Panel - Campbell Measurement and Control Module CR10 Operator's Manual

7.3 THERMOCOUPLE TEMPERATURES
USING THE OPTIONAL CR10TCR TO
MEASURE THE REFERENCE
TEMPERATURE
The CR10TCR Thermocouple Reference is a
temperature reference for thermocouples
measured with the CR10 Measurement and
Control Module. When installed, the CR10TCR
lies between the two analog input terminal
strips of the CR10 Wiring Panel (see Figure
7.3-1). The CR10TCR circuitry, measurement,
and specifications are equivalent to Campbell
Scientific's 107 Temperature Probe.
The CR10TCR is connected to single-ended
channel 1 (1H), excitation channel 3 (E3) and
analog ground (AG). It is measured with
Instruction 11 which excites the probe with a
2.5VAC excitation, makes a single ended
measurement and calculates temperature (°C).
Five differential thermocouples are measured
with Instruction 14. (Refer to the CR10TCR
Manual for instructions on measuring a
thermocouple in differential channel 1.)
The temperature (°C) of the CR10TCR is stored
in Input Location 1 and the thermocouple
temperatures (°C) in Locations 2-6.
SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES
FIGURE 7.3-1. CR10TCR Mounted on the CR10 Wiring Panel
PROGRAM
01: P11
01: 1
02: 1
03: 3
04: 1
05: 1
06: 0
02: P14
01: 5
02: 22
03: 2
04: 1
05: 1
06: 2
07: 1
08: 0
7.4 THERMOCOUPLE TEMPERATURES
USING AN EXTERNAL REFERENCE
JUNCTION
When a number of thermocouple measurements
are made at some distance from the CR10, it is
often better to use a reference junction box
located at the site rather than use the CR10TCR
Thermocouple Reference. Use of the external
reference junction reduces the required length of
expensive thermocouple wire as regular copper
wire can be used between the junction box (J-box)
and CR10. In addition, if the temperature gradient
between the J-box and the thermocouple
measurement junction is smaller than the gradient
between the CR10 and the measurement junction,
thermocouple accuracy is improved.
Temp 107 Probe
Rep
IN Chan
Excite all reps w/EXchan 3
Loc [:REF TEMP ]
Mult
Offset
Thermocouple Temp (DIFF)
Reps
7.5 mV 60 Hz rejection Range
IN Chan
Type T (Copper-Constantan)
Ref Temp Loc REF TEMP
Loc [:TC #1 ]
Mult
Offset
7-3