Whatever the source is water, steam or wind, measuring vibrations efficiently and accurately on turbines is a key issue. The choice for a trustworthy analyzer is crucial for both manufacturers and power operators.
Acceptance tests are to be carried out with the highest possible efficiency. Integrating run ups and coast downs, systematic test procedures including dynamic and static parameters are carried out. A powerful integrated multianalyzer allows these tests to be achieved in a minimum amount of time.
Relative shaft vibration is captured with proximity probes. Analyzing this data requires a number of software tools such as orbit and shaft centerline analysis.
ORBIGate, the OROS turbomachinery vibration solution, features these analysis and many more analysis tools. These tools display the physical motion of the shaft and let you detect faults such as oil whirl & whip, preload, misalignment, rub and others.
Gear boxes have a complex vibration signature, usually occurring at high frequencies. The FFT-Diagnostics tool, such as cepstrum, kurtosis and harmonic markers are necessary to describe and understand the generated vibrations. The virtual tachometers management feature allows the analyst to determine the speed and phase information based on the gear ratio.
Imbalance is probably the most common source of vibration on rotating machinery. Depending on the machine and the rotating speed range the rotor can be considered to be rigid or flexible. In the first case, the Single Dual plane Balancing module will be used. In the second case a multiplane approach should be preferred and the associated Multiplane module should be used.
Damaged roller bearings are common. The bearing vibration signatures are usually measured with an accelerometer mounted on the bearing housing. In particular, the OROS FFT-Diagnostics module uses envelope demodulation to analyze these vibration sources to determine if the source is from the roller elements or the races
Torsional vibration and torque fluctuation are usual phenomena especially on large internal combustion engines. The OROS torsional software module utilizes a frequency to voltage converter for speed input providing the following information: the angular velocity profile displays RPM variations. 2 pulse train combination detects torsional resonances.
Reciprocating machines are complex installations. They generate specific vibration signatures. The objective is their performance optimization and faults detections. For example, injection delay, valves faults, segmentation wear can be identified with EngineDiag, the OROS software for reciprocating machines diagnostics.
This software module integrates the machine mechanical properties: number of cylinders, firing order and timing diagram, allowing to provide pertinent decision criteria on the field. Time signal, overall levels as well as angle-frequency representation on the machine cycle are efficient results for diagnostics
Operating deflection shape is an important analysis procedure used to locate machinery and piping system deflection during operation. It is based upon simplified geometry description of the machine train. After measuring the vibration response at multiple locations, the mechanical source can be identified. The ODS software module helps to determine vibration sources, a transmission point and eventually a mechanical modification to be implemented.
When blade dynamic structural characteristics should be determined, they are submitted to modal testing: based on impact hammer testing or shaker excitation. Based on multichannel analyzers, vibration response can be captured by accelerometers or strain gauges. Modal, the OROS Structural Dynamics module, can process the FRFs to give the modal characteristics.
Generators and motors end windings are strongly excited by frequencies at twice the network frequency: any mode nearby that frequency will create high vibration response. FFT analyzers and Modal, the OROS Structural Dynamics module, are well adapted for bump tests acquisition, resonance frequency determination and deflection shapes.
Dynamic coupling between machine trains and their skids or foundations can be a problem during the machine installation and the field acceptance test. Excitation frequencies should not match the response frequencies of the hosting structure: the mounting choice is key. To tackle this issue, OROS products such as transfer functions, ODS, and damping calculations assist the user in the procedures.
The ambient noise generated from rotating machinery can be evaluated using general tools such as the 1/3 octave analysis. But more thorough measurements can be achieved using the sound power value. The sound intensity technique is often completed in the field thanks to its portability and adaptability.