Siemens SITRANS F Operating Instructions Manual page 15

Manual Addendum
To INCREASE the Digital Damping:
1. Press the <1> key while viewing the Test Facilities Graph Screen as shown above. The damping
control [MinDamp #] should appear on the command line at the lower left-hand corner of the
screen.
Note: The number listed to the right of the command code on the screen represents the
exponent in the exponential averaging routine, where the larger the number represents
the greater the digital averaging. Setting this exponent higher than 7 is generally not
recommended.
2, Pressing the <+> key will increase the MinDamp Factor by one unit for each key press. To exit this
mode, press the <0> key on the keypad.
The above example shows that increasing the Digital Damping reduces asynchronous noise.
Setting the Digital Damping factor to a value LOWER than the default value of 4 may be justified in
cases where pulsating flow is present (such as from a reciprocating compressor) or for the purpose
of diagnosing transient signal behavior. A pulsating flow condition that generates more than +/- 45
degrees of phase jitter will generally cause signal correlation problems when any digital averaging is
used. In this case it may be necessary to completely eliminate the digital averaging by reducing the
Digital Damping Factor to 0. In such a case it may also be necessary to install a narrow band tuned
amplifier (Input Module) if too much asynchronous noise exists.
To DECREASE the Digital Damping:
1. Press the <2> key while viewing the Test Facilities Graph Screen. The damping control [MaxDamp
#] should appear on the command line at the lower left-hand corner of the screen.
2. Pressing the <-> key will decrease the MaxDamp Factor by one unit for each key press. To exit this
mode, press the <0> key on the keypad.
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