CEMB USA N100 - Manual (Page 26)

5 - 2 Vibrometer function
− DIS-1 : type 1 displacement sensor (not powered)
− DIS-2 : type 2 displacement sensor (not powered)
When required, the N100 instrument automatically supplies power to the sensor
connected.
Warning:
To obtain a sufficiently accurate measurement must be correctly specified the
sensor effectively connected.
2. Measurement:
Indicates the type of measurement carried out:
− Overall: overall vibration value
− Synchronous measurement: value of the synchronous component at the rotation
velocity (1xRPM) or its multiples (2xRPM, 3xRPM, 4xRPM, 5xRPM)
3. Units of measurement
Select the unit of measurement in which the vibration is to be expressed: the possibilities
are:
− acceleration (g)
− velocity (mm/s or inch/s)
− movement (µm or mils)
Warning:
Displacement and speed measurements can be taken when displacement sensors
are used, however their use means acceleration measurements cannot be taken.
4. Type of vibration
Like all physical sizes, vibration has a value that can vary from one moment to the next;
mathematically it can be described by a function of time. Its overall value can therefore be
calculated in three different types:
− RMS (Root Mean Square): mean square value
the mean value of the previously squared vibration;
the most commonly used, especially for acceleration or velocity measurements. It is
a direct indication of the vibration’s “energy” content: in practice it represents the
power brought with the vibration and discharged onto the supports or bases of the
vibrating structure.
− PK (Peak): peak value
the maximum value reached by the vibration in a certain period of time.
− PP (Peak-to-Peak): peak-to-peak value
the difference between the maximum value and the minimum value reached by the
vibration in a certain period of time;
normally used for movement measurements.