Campbell CR10 PROM, Руководство оператора

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SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES
7-10
coefficient is 0.00385/
°
C. The change in
nonlinearity of a PRT with the temperature
coefficient of 0.00392/
°
C is minute compared
with the slope change. Entering a slope
correction factor of 0.00385/0.00392 = 0.98214
as the multiplier in Instruction 16 results in a
calculated temperature which is well within the
accuracy specifications of the PRT.
PROGRAM
01: P6 Full Bridge
01: 1 Rep
02: 21 2.5 mV 60 Hz rejection Range
03: 3 IN Chan
04: 1 Excite all reps w/EXchan 1
05: 2500 mV Excitation
06: 11 Loc [:Rs/Ro ]
07: 0.001 Mult
08: .02344 Offset
02: P59 BR Transform Rf[X/(1-X)]
01: 1 Rep
02: 11 Loc [:Rs/Ro ]
03: 50 Multiplier (Rf) =R1/R0
03: P16 Temperature RTD
01: 1 Rep
02: 11 R/Ro Loc Rs/Ro
03: 12 Loc [:TEMP C ]
04: .98214 Mult
05: 0 Offset
7.12 PRESSURE TRANSDUCER - 4
WIRE FULL BRIDGE
This example describes a measurement made
with a Druck PDCR 930 depth measurement
pressure transducer. The pressure transducer
was ordered for use with 5 volt positive or negative
excitation and has a range of 5 psi or about 3.5
meters of water. The transducer is used to
measure the depth of water in a stilling well.
Instruction 6, 4 Wire Full Bridge, is used to
measure the pressure transducer. The high
output of the semiconductor strain gage
necessitates the use of the 25 mV input range.
The sensor is calibrated by connecting it to the
CR10 and using Instruction 6, an excitation
voltage of 2500 mV, a multiplier of 1 and an offset
of 0, noting the readings (*6 Mode) with 10 cm of
water above the sensor and with 334.6 cm of
water above the sensor. The output of Instruction
6 is 1000 V
s
/V
x
or millivolts per volt excitation. At
10 cm the reading is 0.19963 mV/V and at 334.6
cm the reading is 6.6485 mV/V. The multiplier to
yield output in cm is:
(334.6 - 10)/(6.6485-.19963) =
50.334 cm/mV/V
The offset is determined after the pressure
transducer is installed in the stilling well. The
sensor is installed 65 cm below the water level
at the time of installation. The depth of water at
this time is determined to be 72.6 cm relative to
the desired reference. When programmed with
the multiplier determined above and an offset of
0, a reading of 65.12 is obtained. The offset for
the actual measurements is thus determined to
be 72.6 - 65.12 = 7.48 cm.
The lead length is approximately 10 feet, so
there is no appreciable error due to lead wire
resistance.
01: P6 Full Bridge
01: 1 Rep
02: 23 25 mV 60 Hz rejection Range
03: 1 IN Chan
04: 1 Excite all reps w/EXchan 1
05: 2500 mV Excitation
06: 1 Loc [:HT cm ]
07: 50.334 Mult
08: 7.48 Offset