Vibrograph

Vibrograph for motor transformer
Regarding the 3 Vibration Modes

Generally speaking, the following 3 vibration-unit modes are available.
* Vibration displacement
* Vibration speed
* Vibration acceleration

Vibration displacement

Vibration displacement refers to the vibration distance, or the approximate distance along which vibration is taking place and is expressed by full amplitude (mmP-P) and single amplitude (mmO-P). The unit [um] is also sometimes used. This vibration displacement is often used to assess the vibration of rotating shafts, for example.

Vibration speed

Vibration Speed refers to a value resulting from differentiation of the vibration displacement by time and is expressed in units of [mm/sec] or [cm/sec]. The electro-kinetic pickup is capable of acquiring the vibration speed output and displaying the vibration speed without an operational amplifier for ease of usage.

Vibration acceleration

Vibration Acceleration refers to a value resulting from differentiation of the vibration speed by time and expresses speed as time differences and uses the units (G) or (m／sec²) that are also used to express the gravitational acceleration of the Earth.

If the vibration speed is constant, the greater the vibration displacement, the greater the acceleration; in addition, if the vibration speed is constant, the greater the vibration displacement. Moreover, if object is placed on a horizontal surface vibrating perpendicularly rises, the surface is vibrating at a value in excess if 1 G. From the foregoing, it is believed that this mode is more effective than the other 2 modes when evaluating the effect on other objects of the vibration energy of a vibrating object. The relationship between these three modes is shown in the figure below.

For the reasons described above, ECG Kokusai’s vibration tester for motors and transformers makes use of the acceleration mode.