High Level Rates - Emerson Rosemount 3308 Reference Manual

Reference Manual
00809-XXXX-4811, Rev AA
February 2012

High Level Rates

PRELIMINARY
The measurement signal is filtered in order to minimize the influence of
disturbing noise. In most measurement situations this does not have a
noticeable effect on the response time to level changes. If high level rates
occur it may however be necessary to reduce the damping value in order to
allow the transmitter to respond quicker. If there is too much noise the
damping value may be increased in order to get a stable measurement signal.
You can use the RCT software or a Field Communicator to change the
Damping value. For the HART Communicator use the key sequence
[1, 3, 5].
In the RCT software open the Setup>Output tab and enter the desired
Damping value:
Output tab
Damping
The Damping parameter determines how quickly the transmitter responds to
level changes and how robust the measurement signal is against noise.
Technically, a damping value of 10 means that in 10 seconds the output from
the transmitter is about 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 be able to track the surface. On the other
hand, in noisy environments, and if level rates are low, it may be better to
increase the damping value to have a stable output signal.
Rosemount 3308
7-7