Campbell Scientific CS547A-L Conductivity/Temperature Probe and A547A Interface - Manual (Page 26)

CS547A Conductivity and Temperature Probe and A547 Interface
11. Electrically Noisy Environments
AC power lines can be the source of electrical noise. If the datalogger is in an
electronically noisy environment, the 107 temperature measurement should be
measured with longer integration periods than 250µSec. For CRBasic loggers,
the Therm107 Integration parameter has options for 60 Hz rejection that
impose a long 3mSec integration. Sixty and 50 Hz rejection is also available
as an option in the Excitation Channel parameter of Instruction 11 for the
CR10X, CR510, and CR23X dataloggers. For the CR10, CR21X and CR7, the
107 should be measured with the AC half bridge (Instruction 5).
Example 11-1, CR1000 measurement instruction with 60 Hz rejection:
Therm107(TempDeg_C,1,3,2,0,_60Hz,1.0,0.0)
Example 11-2. Sample CR10(X) Instructions Using AC Half Bridge
1: AC Half Bridge (P5)
1: 1
Rep
2: 22** 7.5 mV 60 Hz rejection Range
3: 3* IN Chan
4: 2* Excite all reps w/EXchan 2
5: 2000** mV Excitation
6: 11* Loc [ Air_Temp ]
7: 800 Mult
8: 0 Offset
2: Polynomial (P55)
1: 1
Rep
2: 11* X Loc [ Air_Temp ]
3: 11* F(X) Loc [ Air_Temp ]
4: -53.46 C0
5: 90.807 C1
6: -83.257 C2
7: 52.283 C3
8: -16.723 C4
9: 2.211
C5
* Proper entries will vary with program and datalogger channel and input location assignments.
** On the 21X and CR7 use the 15 mV input range and 4000 mV excitation.
12. Long Lead Lengths Temperature
If the CS547A has lead lengths of more than 300 feet, use the DC Half Bridge
instruction (Instruction 4) with a 2 millisecond delay to measure temperature.
The delay provides a longer settling time before the measurement is made. Do
not use the CS547A with long lead lengths in an electrically noisy
environment.
For all CRBasic loggers, as well as CR10X, CR510 and CR23X that have 60
and 50 Hz integration options, this forces a 3 mSec settling time, which
accommodates long lead lengths. Longer settling times can be entered into the
Settling Time parameter.
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