Misalignment, unbalance and derived dynamic effects such as gyroscopic action & whirl force the component of a machine to vibrate.
Vibration may increase wear and other forces influences and lead to failure.
Hence signal sensing for vibration monitoring is carried out by accelerometer, velocity transducer, or inductive proximity probes.
The analysis is then carried out of either the displacement, velocity or acceleration of vibration. this produces peaks of high vibration at discrete frequencies.
(i) For Fault Analysis - Vibration monitoring is carried for the bearings and the turbine blade. Different signatory discrete frequency shall tell where the fault lies.
(ii)For Condition Monitoring - Roller Bearing generates shock pulse waves in operation. Measurement of these would provide an effective monitoring of such bearing. A special sensor & accelerometer are attached at loaded zone by using snap on coupling.
The signal received is passed through band filter that selects high frequency which are converted into pulses & displayed.
The fluctuation in curve are caused by variation in extent of damage and bearing rolling out of regions of existing damage. The normal maximum shock pulse limits can be calculated for very bearings.
When normal limits is passed, the shock pulses increases rapidly to approach the maximum allowed, before breakdown becomes likely.
(iii)As a substitute to opening up machinery for survey
Analysis report obtained gives proper condition of bearings and motor condition.Surveys can be passed on basis of these reports without opening up the machinery. they can be used as a substitute for class survey where agreement has been reached with classification society.
Machinery which is operated with condition monitoring need only be opened for examaination & repair when readings indicate a deterioration.
1 comment:
Some reciprocating machineries are using vibration measurement method to determine its running condition.
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