Basic Analysis Flashcards
What is DAT and how do you calculate it?
Data Acquisition Time - Time to acquire data set
Number of Lines (N) Divided by Frequency Span (Fmax)…
How do you calculate the Period of a Section?
Counting the number of minor divisions in one cycle. Then multiplying that by the time value of each division.
Convert Sec/Cycle to Cycle/Sec
What unit is Cycles/Sec Equivalent to?
F= 1/T
F: Frequency
T: Period
Herts, Hz
Convert CPS to CPM
CPM to CPS
Multiply by 60
Divide by 60
1X
Frequency =Operating Speed
2X
Frequency = 2X Operating Speed
Orders
Multiples of Operating Speed
Harmonic Vibrations in timewave indicate
One Frequency/Sine Wave
Mass Unbalance related to RPM
Distinctive Pulses in timewave indicate
Rolling Element or Broken gear teeth faults
When Analyst sets up Analyzer, three decisions have to be made…
1) Fmax: Maximum Frequency
2) Number of Lines
3) Window(Type of Analysis)
Random Vibration in Timewave Form indicate
Flow Issues
How to Calculate Resolution(Hz):
Beats in Time wave indicate
two components of different vibrations are nearby.
When a forcing frequency such as operating speed is close to or equal to a natural frequency, the condition of _____________ occurs and the _________ is amplified
Resonance
Vibration
The frequency of the rotor that matches the natural frequency of the Machine is called ____________________
Critical Speed
Mass Unbalance occurs when the _____________ and the __________ of a rotor do not coincide.
Geometric Center (Shaft Centerline)
Mass Center
Mass unbalance is sometimes difficult to distinguish between misalignment in vibration analysis because
They both show up in 1x. A phase analysis would be required to see further because the nature of the forces are different.
Looseness can be identified in the spectrum as
It is caused by
Once per revolution vibration plus orders of operating speed.
This is caused by excessive bearing clearances and untightened bolts.
Beats occur when…
This produces what in the timewave
two vibration sources have frequencies close to each other or a vibration source close to a natural frequency.
Excessive Amplitudes
When a Rolling element passes over a bearing defect in the races or cages, __________________ are generated.
Pulse like forces
Rolling element bearings generates ________________ unique to their geometry and ____________
frequencies
operating speed
