Rockwell Automation 1440-VAD02-01RA XM-123 Aeroderivative Module - Manual (Page 65)

Publication GMSI10-UM003D-EN-P - May 2010
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Speed Measurement Parameter
Use the speed measurement parameter to configure the filtering performed on
the speed measurement.
Tachometer Parameters The tachometer parameters define the characteristics of the tachometer and
determine the signal processing that will be performed on the tachometer
signal.
Tachometer Transducer Parameters
Speed Measurement Parameter
Parameter Name Description Values/Comments
Exponential Averaging Time
Constant Sets the 3-dB bandwidth for the digital filter used to
calculate the Speed Value. The 3-dB bandwidth is
roughly equal to 1 / (2
π
x Exponential Averaging
Time Constant). The greater the value entered, the
longer the response of the measured Speed Value to
a change in the input signal (less sensitive to noise
in the signal). See example table below.
Time Constant
(milliseconds) -3dB Frequency
(Hz)
Settling Time
(milliseconds)
5 31.8310 11
10 15.9155 22
20 7.9577 44
50 3.1831 110
100 1.5915 220
1200 0.1326 2640
Tachometer Transducer Parameters
Parameter Name Description Values/Comments
Tachometer Name (XM Serial
Configuration Utility only) A descriptive name to help identify the tachometer in
the XM Serial Configuration Utility software. Maximum 18 characters