Mechanical Vibration

1. DIAGNOSING FAULT
CONDITIONS WITH PHASE
GHIFARI YUKHA NIJAMUDIN 15/379047/TK/42989
HAFIDZ MIFTAH ROSADI 15/379048/TK/42990
MOHAMMAD RHEZA FAHLEVI 15/379059/TK/43001
MUHAMMAD ABID MUZHAFFAR 15/379060/TK/43002

2. VIBRATION ANALYSIS
• The vibration analysis process involves determining the vibration
severity, identifying frequencies and patterns, associating the peaks
and patterns with mechanical or electrical components, forming
conclusions and, if necessary, making recommendations for repair.
• There is one diagnostic technique which quickly gets to the source
of most vibration problems. It is possibly the most powerful of all
vibration diagnostic techniques. It has been around as long as
vibration analysis itself yet hasn’t gotten a lot of attention, and it’s
rare to find good information about the subject. What is this
technique? It’s called phase analysis.

3. WAVEFORM AND SPECTRUM

4. PHASE
• Phase is the position of a rotating
part at any instant with respect to
a fixed point. Phase gives us the
vibration direction. Tuning a car
engine using a timing light and
inductive sensor is an application
of phase analysis (Figure 2).

5. TYPE OF PHASE ANALYSIS
• A phase study is a collection of phase measurements made on a
machine or structure and evaluated to reveal information about
relative motion between components. In vibration analysis, phase is
measured using absolute or relative techniques.

6. ABSOLUTE PHASE
• Absolute phase is measured with one sensor and one tachometer
referencing a mark on the rotating shaft (Figure 3). At each
measurement point, the analyzer calculates the time between the
tachometer trigger and the next positive waveform peak vibration.
This time interval is converted to degrees and displayed as the
absolute phase (Figure 4). Phase can be measured at shaft
rotational frequency or any whole number multiple of shaft speed
(synchronous frequencies). Absolute phase is required for rotor
balancing.

7. ABSOLUTE PHASE

8. RELATIVE PHASE
• Relative phase is measured on a multi-channel vibration analyzer
using two or more (similar type) vibration sensors. The analyzer
must be able to measure cross-channel phase. One single-axis
sensor serves as the fixed reference and is placed somewhere on
the machine (typically on a bearing housing). Another single-axis or
triaxial sensor is moved sequentially to all of the other test points
(Figure 5). At each test point, the analyzer compares waveforms
between the fixed and roving sensors. Relative phase is the time
difference between the waveforms at a specific frequency converted
to degrees (Figure 6). Relative phase does not require a tachometer
so phase can be measured at any frequency.

9. RELATIVE PHASE

10. CAUSE USING PHASE ANALYSIS
• Everyone needs phase analysis. A phase study should be made on
problem machines when the source of the vibration is not clear or
when it is necessary to confirm suspected sources of vibration. A
phase study might include points measured only on the machine
bearings or it can include points over the entire machine from the
foundation up to the bearings.

11. EXAMPLE

12. EXAMPLE

13. EXAMPLE

14. EXAMPLE

15. REFERENCE
• http://www.reliableplant.com/Read/26843/phase-analysis-vibration

16. TERIMA KASIH