Emerson Rosemount 1152 Alphaline, Reference Manual

Page: 23 / 68

Reference Manual
00809-0100-4235, Rev BA
April 2007
3-3
Rosemount 1152
NOTE
On Range Codes 6, 7, 8, 9, and 10, the span adjustment has a significant
effect on zero. This effect becomes increasingly more pronounced as span is
decreased. The span effect on zero is great enough in some instances to
cause a decrease in full-scale output with an increase in span.
Figure 3-1. Linearity Adjustment,
A or D Output.
Linearity Adjustment
(A and D Output)
In addition to the span and zero adjustments, there is a linearity adjustment
located inside the transmitter, accessible through the amplifier board.
Linearity is factory adjusted for optimum performance over the calibrated
range of the instrument and is not normally adjusted in the field. To maximize
linearity over some particular range, use the linearity adjustment. It is
necessary to readjust span after adjusting linearity. Figure 3-1 on page 3-3
and Figure 3-2 on page 3-4 show the location of the linearity adjustment.
Damping Adjustment
(D Output Only)
The stepped variable time-constant amplifier board is designed to permit
dampening out of rapid pulsations in the pressure source by selecting one of
four time constant settings. The available settings provide time-constant
values (63.2 percent of total response) between 0.2 seconds
(1)
and 2.0
seconds. These time-constants are selected by manually setting a
four-position rotary switch located on the amplifier board. The switch positions
are labeled 1, 2, 3, and 4 which correspond to time-constant values of 0.2,
0.5, 1.0, and 2.0 seconds, respectively. The tolerance of these values is ±20
percent. Figure 3-2 on page 3-4 shows the four-position rotary switch.
Select the shortest possible time constant setting. For example, if the 0.5
second time constant is sufficient to dampen out the undesired pulsations,
then do not use a longer time constant.
Since transmitter accuracy is not influenced by the time constant setting, the
transmitter can be calibrated with the switch in any one of the four positions.
However, position 1 gives the fastest time response during calibration. The
switch can be reset later to any other position without further adjustments.
Linearity
Adjustment
Access Hole
Electronics Side of
Transmitter Housing
(Cover Removed)
(1) The actual minimum time constant (at 100 °F) is range dependent as follows: 0.3 seconds
nominal (Range Code 3); 0.2 seconds nominal (Range Codes 4 and 5); 0.1 seconds nominal
(Range Codes 6, 7, 8, 9, and 10).
1152-0392A