Latvian Maritime academy

Figure 3. Distribution of magnetic induction in air gap in the axial direction of the machine
Table 1.
Level of the shift
max / sim
B (%)
(basic harmonic)
B (%)
(tooth harmonic)
1.25 - 5 -12
1.5 -12 -23
1.75 -19 - 31
Conclusions
1. The proposed method give an opportunity for technical monitoring of the bearing units of the
electrical machines with the shift of rotor according to the axis of stator along all 3 space axes (X-Y-Z).
2. With the shift of the rotor ( max / sim = 1,75 ) (the defect of one of the bearings) the meanings of
the basic harmonic of the induction in air gap reduce for up to 20%, but of the tooth one up to 30 %.
These changes are the diagnostic parameters of the technical monitoring of the electrical machines.
3. The defects of the piston-cylinder group, gas-distributing mechanism and other aggregates of the
diesel and driven mechanism (pump, fan, etc.) also influence the harmonic composition of the magnetic
induction in air gap but their frequency is significantly lower that those produced of the bearings.
4. This method allows on-the-run monitor of the bearing units of electrical machines without their
stopping, breaking of the technology process and without withdrawal.
5. The data of the monitoring give a possibility of prognoses of the residual life of the bearing units,
transmit a part of sudden failures into the category of gradual failures and determine the level of the
necessary service.
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