Iz konteksta sledi da se radi o mehaničkoj pobudi vibracija konstrukcije, izazvanoj obrtanjem vratila ventilatora, a ne o električnoj pobudi (namotaja) elektro-motora.

"3. POBUDE KONSTRUKCIJE - Frekvence dinamičke pobude (prinude) usled obrtanja vratila ventilatora iznose:-" > “3. MECHANICAL EXCITATION OF STRUCTURE – Frequencies of mechanical excitation caused by rotation of fan shaft are:...”


“Glossary of Terms for Data Physics Dynamic Analysers and Vibration controllers
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Forced vibration - The vibratory motion of a system caused by some mechanical excitation. If the excitation is periodic and continuous, the response motion eventually becomes steady-state.
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First order vibration - Rotating machine vibration caused by shaft unbalance. Frequency in hertz (Hz) is calculated by shaft RPM/60. Also called 1x vibration. Additional orders, 2x, 3x .... 36x, etc. are caused by other mechanisms
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Frequency Response - (FRF) A characteristic of a system that has a measured response resulting from a known applied input. In the case of a mechanical structure, the frequency response is the spectrum of the vibration of the structure divided by the spectrum of the input force to the system.”
(http://www.signalstar.co.uk/glossaryofterms.htm)


“Vibration Analysis of Reactor Assembly Internals for Prototype Fast Breeder
Reactor
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The above mentioned components are analysed for mechanical and flow induced vibrations. The source of mechanical excitation is PSP vibration. Hence, the PSP is analysed first for the excitation forces caused by PSP unbalance and the results of analysis provides the data for checking the acceptability of vibration amplitudes and resonance condition for the shaft.”
(http://www.iasmirt.org/SMiRT17/J02-6.pdf)


“Machine Condition Monitoring
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Forced Vibration - Vibration of a system caused by an imposed force or mechanical excitation . If the excitation is periodic and continuous, the response motion eventually becomes steady-state.”
(http://www.mcm-ltd.co.uk/glossary/f_glossary.asp)