Vibration monitoring

‘Spectrum analysis’ is equivalent to transforming the information in the signal from the ‘time domain’ into the ‘frequency domain’

• True

• False

From the time domain wave form it would be very easy to extract the individual frequency components and their levels

• True

• False

Periodic signals have wave forms whose pattern repeats at equal increments of time (harmonic series)

• True

• False

The mathematical transform which converts the time domain wave form into the frequency domain is called the Fourier transform (FFT)

• True

• False

The vibration of an object is always caused by an excitation force

• True

• False

To convert the frequency in Hz to RPM or CPM:

• Multiply the frequency by 60

• Divide the frequency by 60

• Multiply the frequency by 10

• Divide the frequency by 10

To find the location of the heavy spot in an imbalanced rotor, you need to use:

• A spectrum analyser alone

• A tachometer alone

• A tachometer and phase analysis

• None of the answers are correct

A 90 degrees phase shift is (select the correct answers)

• One fourth of one period

• Out of phase

• Phase between displacement and velocity

Velocity vibration is measured in

• g RMS

• mm peak to peak

• mm/sec RMS

• mm peak