Mr Site Vibration Test Guidelines; Test Measurements; Equipment (Spectral Analyzer) Set-Up - GE SIGNA Voyager Pre-Installation

2 MR Site Vibration Test Guidelines

2.1 Test Measurements

1. Vibration measurements must be in the range of 10
required sensitivity to these levels
2. Instrumentation must have a low tolerance to temperature effects since many times the low
frequency thermal drift may influence the measurements
3. All measured data must be acquired real time. Recording of vibration data will not allow for a
proper site survey, specifically when studying transient vibration and when searching for
specific vibration sources
4. All analyses must be narrow-band Fast Fourier Transforms (FFT) over the frequency bands
listed in Table 7-1
5. Time histories of the vibration must be recorded as acceleration levels vs. time. The
resolution of the time history must be adjusted to clearly capture the transient event. The
analyzer set-up will be site dependent and, in special cases, vibration response dependent.
It is the responsibility of the vibration consultant to study the transient environment, capture
data to confirm that transient activity exceeds the trigger level, then expand the time history
data to exhibit the structural response
Table 7-1: Frequency Bands for FFT

2.2 Equipment (Spectral Analyzer) Set-Up

1. Frequency average should be a minimum of 20 linear averages (Do not use peak hold or
1/3 octave analysis)
2. Average and store should be a minimum of 20 plots steady state and 20 plots transient to
support the consistency of the site vibrations
3. Hanning windows must be applied to the entire spectra
4. Spectrum analyzers capable of these measurements are readily available for purchase or
rental. Models, such as the HP 3560A, Nicolet Phaszer, B&K Pulse, and HP 35670, are all
capable of making the site vibration measurements. Accelerometers must have the
capability to measure from 0.2 Hz beyond 50 Hz. Time histories can be recorded using any
of the analyzers listed above
NOTE: The equipment mentioned is for example only. It is the responsibility of the
Engineering Test Firm to provide equipment that will allow measurements
compliant with this guideline.
150
Frequency Band
0.2 to 50 Hz
SIGNA Voyager Pre-Installation
Direction 5680008–1EN, Revision 2
g. Test equipment must have the
-6
Frequency Resolution
Δf= 0.125 Hz
2 MR Site Vibration Test Guidelines