Rosemount 5401, Справочное руководство

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Reference Manual
00809-0100-4026, Rev FA
July 2009
Rosemount 5400 Series
C-6
Slow Search Speed
This parameter indicates the speed the search region (Slow Search window)
is expanded when the
Slow Search
function is active.
Double Surface
Indicates that there are two liquids or foam in the tank resulting in two
reflecting surfaces. The upper liquid or foam layer must be partially
transparent to the radar signal.
The
Select Lower Surface
parameter specifies the surface layer selected as
the surface.
Upper Product Dielectric Constant
This is the dielectric constant for the upper product if there is a double surface
situation. A more precise value results in better accuracy for the lower surface
level.
Select Lower Surface
This function should only be used if
Double Surface
is set. If
Select Lower
Surface
is set, the lower surface is identified as the product surface. If not, the
upper surface is used.
Echo Timeout
Echo Timeout defines the time, in seconds, after the echo has been lost,
before the transmitter starts searching for a surface echo. The transmitter will
not start searching, or trigger any alarms, until this time has elapsed.
Close Distance Window
This parameter defines a window centered at the current surface position
where new surface echo candidates can be selected. The size of the window
is ±CloseDist. Echoes outside this window will not be considered surface
echoes and the transmitter will jump to the strongest echo inside this window.
If there are rapid level changes in the tank, the value of the Close Distance
Window can be increased to prevent the transmitter from missing level
changes. On the other hand, a large value may cause the transmitter to select
an invalid echo as the surface echo.
Filter Settings
Damping Value
The Damping Value parameter determines how quickly the transmitter
responds to level changes and how robust the measurement signal is against
noise. A damping value of 10 indicates that in 10 seconds the output from the
transmitter is approximately 63% of the new level value. Consequently, when
there are rapid level changes in the tank, it may be necessary to decrease the
Damping Value for the transmitter to track the surface. In noisy environments,
with low level rates, it may be best to increase the damping value for a stable
output signal.
Activate Jump Filter
The Jump Filter is typically used for turbulent surface applications where it
smooths the echo tracking as the level passes, for example, an agitator. If the
surface echo is lost, and a new surface echo is found, the Jump Filter has the
transmitter wait before jumping to the new echo so it can be validated. During
that time the new echo has to be considered a valid echo.