Reference Manual
00809-0100-4808, Rev CA
June 2008
Rosemount 3051N
2-20
NOTE
Use a precision resistor for optimum accuracy. If you add a resistor to the
loop, ensure that the power supply is sufficient to power the transmitter to a
20 mA output with the additional loop resistance.
Compensating Rosemount 3051N Range 4 and 5 Differential Transmitters for Line Pressure Rosemount 3051N Range 4 and Range 5 pressure transmitters require a
special calibration procedure when used in differential pressure applications.
The purpose of this procedure is to optimize transmitter performance by
reducing the effect of static line pressure (Ps) in these applications.
Rosemount 3051N differential pressure transmitter ranges 0, 1, 2, and 3 do
not require this procedure because the optimization occurs in the sensor. See
“Static Pressure Effect” on page 5-3 for additional details.
Applying high static pressure to Rosemount 3051N Range 4 and Range 5
pressure transmitters causes a systematic shift in the output. This shift is
linear with static pressure; correct it by performing the “Full Trim” on
page 2-18, after determining the corrected input values as noted below.
The following specifications show the static pressure effect for Rosemount
3051N Range 4 and Range 5 transmitters used in differential pressure
applications:
Zero Effect:
±0.1% of the upper range limit per 1000 psi (6,9 MPa) for line pressures
(Ps) from 0 to 2000 psi (0 to 13,8 MPa)
±[0.2 + 0.2 (Ps-2000) / 1000]% of the upper range limit per 1000 psi
(6,9 MPa) for line pressures above 2000 psi (13,8 MPa) and ≤ 3626 psi
(25 MPa)
Span Effect:
Correctable to ±0.2% of reading per 1000 psi for line pressures from 0 to
3626 psi.
The systematic span shift caused by the application of static line pressure is
–1.00% of input reading per 1000 psi for 3051N Range 4 transmitters, and
–1.25% of reading per 1000 psi for Range 5 transmitters.
Use the following example to compute corrected input values.
Example
A Rosemount 3051ND4 transmitter will be used in a differential pressure
application where the static line pressure is 1200 psi. The transmitter is
ranged so that the output is 4 mA at 500 inH2O and 20 mA at 1500 inH2O.
To correct for systematic error caused by high static line pressure, first use
the following formulas to determine corrected values for the low trim and
high trim.
LTc = LRV + S (LRV) Ps
Where: LTc = Corrected Low Trim Value
LRV = Lower Range Value
S = –(Systematic Span shift per specification)
Ps = Static Line Pressure