Emerson 8800A, Product Manual

Page: 69 / 160

3-21
Operation
Sig/Tr (Signal/Trigger Level Ratio)
The Signal to Trigger Level Ratio is a variable that indicates the
flow signal strength to trigger level ratio. This ratio indicates if there is
enough flow signal strength for the meter to work properly. For
accurate flow measurement, the ratio should be greater than 4:1.
Values greater that 4:1 will allow increased filtering for noisy
applications. For ratios greater than 4:1, with sufficient density, the
Auto Adjust Filter function can be utilized to optimize the
measurable range of the flowmeter.
Ratios less than 4:1 may indicate applications with very low densities
and/or applications with excessive filtering.
Auto Adjust Filter
The Auto Adjust Filter is a function that can be used to optimize the
range of the flowmeter based on the density of the fluid. The electronics
uses process density to calculate the minimum measurable flow rate,
while retaining at least a 4:1 signal to the trigger level ratio. This
function will also reset all of the filters to optimize the flowmeter
performance over the new range.
Manual Filter Adjust
Manual Filter Adjust allows you to manually adjust the following
settings: Low Flow Cutoff, Low Pass Filter, and Trigger Level, while
monitoring flow and or sig/tr.
Flow
Flow is the actual measured flow rate in the line. On the bench, the PV
value should be zero. Check the units on the PV to make sure they are
configured correctly. See PV Units if the units format is not correct. Use
the Process Variable Units function to select the units for your
application.
Sig/Tr (Signal/Trigger Level Ratio)
The Signal to Trigger Level Ratio is a variable that indicates the
flow signal strength to trigger level ratio. This ratio indicates if there is
enough flow signal strength for the meter to work properly. For
accurate flow measurement, the ratio should be greater than 4:1.
Values greater that 4:1 will allow increased filtering for noisy
applications. For ratios greater than 4:1, with sufficient density, the
Optimize Flow Range function can be utilized to optimize the
measurable range of the flowmeter.
Ratios less than 4:1 may indicate applications with very low densities
and/or applications with excessive filtering.
HART Comm. 1, 4, 4, 1, 3
HART Comm. 1, 4, 4, 1, 4
HART Comm. 1, 4, 4, 2
HART Comm. 1, 4, 4, 2, 1
HART Comm. 1, 4, 4, 2, 2