Emerson manual Line Pressure, Zero Effect, Span Effect, Rosemount 3051N, Reference Manual

Rosemount 3051N

Reference Manual

00809-0100-4808, Rev CA June 2008

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 5-3for 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

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