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Reference Manual
00809-0100-4514, Rev BA
January 2008
Rosemount 1154
3-6
The damping adjustment permits damping of rapid pressure variations by
adjusting the single-turn trim potentiometer located on the upper right-hand
side of the amplifier board (see Figure 3-4). The available settings, when
adjusted to the maximum position, provide time-constant values of at least 1.2
seconds for Range Code 4 and 0.8 seconds for Range Codes 5–9 and 0.
Transmitters with the electronic damping option are calibrated and shipped
with the adjustment set at the counterclockwise stop, giving the minimum
time-constant.
To adjust the damping, turn the damping adjustment potentiometer until the
desired time-constant is obtained. It is best to set the damping to the shortest
possible time-constant. Since transmitter calibration is not affected by the
damping setting, you may adjust the damping with the transmitter installed on
the process.
NOTE
If you remove either cover during the above procedures, replace the O-ring
and torque the cover per the instructions given in Section 5 Maintenance
and Troubleshooting of this manual. Spare cover O-rings are supplied with
each transmitter.
Correction For High Line
Pressure (Rosemount
1154DP and 1154HP
Only)
Span
If a differential transmitter is calibrated with the low side at ambient pressure
but will be used at high line pressure, correct the span adjustment to
compensate for the effect of static pressure on the unit. If zero is elevated or
suppressed, also correct the zero adjustment. Correction factors, expressed
in percent of differential pressure input at end points per 1,000 psi static
pressure, are:
Range Codes 4, 5, and 8:
+0.75% of input/1,000 psi
Range Codes 6 and 7:
+1.25% of input/1,000 psi
The correction procedure below uses the following example:
Range Code 5, calibrated at –100 to 300 inH
2
O, to be operated at 1,200 psi
line pressure. Note that steps 3–6 are omitted for ranges based at zero
differential pressure.
The damping adjustment potentiometer has positive stops at both ends. Forcing
the potentiometer beyond the stops may cause permanent damage.