8.3.3.3
Vibration Displacement
Inputs 1-8 support Proximitor sensors to collect air gap, wideband vibration, and 1x/2x vibration vectors relative to a specified
Keyphasor channel. In Heavy Duty turbine applications, Proximitors are used to monitor the position of a rotating shaft.
Vibration Displacement algorithms report a filtered air gap value, and peak-to-peak displacement value, and an optional
vibration phasor relative to a specified Keyphasor channel.
Vibration Displacement Input Processing
GAPn_VIBn – The filtered Position or Gap value in engineering units (EU).
Gap values are filtered through a 2-pole, low-pass filter with a fixed cutoff frequency of 8 Hz. The output of the gap filter is
passed through a rolling average filter prior to scaling. Gap Values are converted from Volts to EU. For Vibration
Displacement applications, Gap values are magnitude quantities, so they are always positive.
Gap
Filter
Mvg
Avg
Filter
A/B
abs (A)
A
A
|A|
B
V
GAP
V
FILT
EU
GAP
GAPn_VIBn
Scale(V/EU)
V
PROX
VIBn – Wideband Vibration Displacement (Peak-Peak) in engineering units (EU).
Wideband vibration information is passed through a variable scan period peak detection function. The length of the peak
detection is determined by the Keyphasor 1 detected speed in RPM.
Wideband Vibration Scan Period
Shaft speed (RPM)
Scan period (ms)
0 – 60
160
60-480
2000
480-2250
250
>2250
160
Attention
Peak Detection function always uses KPH1 RPM, even when the sensor is configured
to use KPH2 for 1x/2x Vibration Phasor calculations.
The output of the peak detection function (V
PK-PK
) is passed through an adjustable 1-pole, low-pass filter prior to scaling.
V
PK-PK
is converted from Volts to EU. For H1B systems, a lower latency peak detection function can be enabled by changing
the OperatingMode parameter to Enhanced. This function will update every frame, instead of every scan period.
Note
Sensors monitoring position of rotating elements typically measure Peak-to-Peak. RMS calculations can be used
instead if needed.
VIB_1Xn, VIB_2Xn – Vibration Phasor Magnitude (Peak-Peak) for 1st/2nd harmonic of Keyphasor frequency in engineering
units (EU).
Vib1xPHn, Vib2xPHn – Phase Angle between Keyphasor and VIB_1Xn/VIB_2Xn vibration phasor in degrees.
YVIB Vibration Monitor Modules
GEH-6855_Vol_II System Guide 249
Public Information