Download - Orbits and SCL Presentation
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October 30, 2007 SKF Group Slide 0
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October 30, 2007 SKF Group Slide 1
3Orbits and Shaft Centerline
2014-01-29 SKF Slide 1 [Code]SKF [Organisation]
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October 30, 2007 SKF Group Slide 2
Purpose of Orbits and Shaft Centerline
Bearing cap vibration information (acceleration/velocity) alonecannot truly indicate a machine shaftss dynamic responses.
Eddy current probes (ECP) measure the direct relative responseof the shaft to the stationary bearing housing.
Orbit displays are useful to study the shafts relative dynamicmovements and clearly show rub, whirl etc. conditions as theyhappen.
Shaft Centerline displays show the shafts average position withrespect to bearing clearance.
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October 30, 2007 SKF Group Slide 3
Eddy current signals
An Eddy Current Probe (ECP) signal can be broken downinto two parts:
A DC signal which tracks the shafts average position. An AC signal which tracks the shafts dynamic motion.
The AC part of the signal forms the Orbit display
The DC part of the signal forms the Shaft Centerline display.
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October 30, 2007 SKF Group Slide 4
Orbit and Shaft Centerline
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October 30, 2007 SKF Group Slide 5
What is an orbit ?
An orbit is the combination of t w o dynamic time domainsignals, creating a graphic of the shafts movementaround its center point.
The two dynamic time domain signals must be acquiredat the same time, with the same Fmax and the samenumber of data samples.Data acquisition systems that can be used to createorbits are: GX, DMx, IMx.
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Constructing an Orbit
An orbit plots time domainsignals are normally formedby ECP signals mountedunder a 90 degree angle.
Common sensor positionsare:0 and 90 degrees45 and 135 degrees
T i m e
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October 30, 2007 SKF Group Slide 7
The Orbit Display
Flash-Blank in indicates direction of orbitprecession. (This is not necessarily the
same as the direction of rotation
Indication of Sensor locations Banded time cursor allows for precise selection
of orbit curve anywhere within the time data.
Customer programmablereference
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October 30, 2007 SKF Group Slide 8
Filtered Orbits
Filtered Orbits with the pressof a button cycles through 1x,2x, 3x and raw.
Filtered Orbitsprovide clarity inthe synchronousmodes of vibration
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October 30, 2007 SKF Group Slide 9
Shaft Centerline (SCL)
Speed plotted along thestartup center line.
Cursor indicateseccentricity value
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October 30, 2007 SKF Group Slide 10
Vector and Waveform compensation
The vibration levels seen as slow-roll are typically caused by one ormore of the following: Mechanical run out (e.g., scratches, non-homogenous materials) Electrical run out (e.g., driver noise) Shaft eccentricityThis is not real vibration and should be removed from the actualvibration signal. This process is referred to as run out compensation.
@ptitude Analyst supports vector as well as waveformcompensation.
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October 30, 2007 SKF Group Slide 11
Orbit & SCL POINT setup
Orbit setup allows arbitrarysensor angles. The actualangle is stored with the data sothat when probe positions arechanged, the data displaysremain correct.
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October 30, 2007 SKF Group Slide 12
Vector & Waveform setup
Vector compensation issupported for the first threevectors 1x, 2x, 3x.
Waveform compensation isalso supported.
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October 30, 2007 SKF Group Slide 13
Triax POINT setup
Requires triax sensorconnected to GX(version 2.0 or higher)
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October 30, 2007 SKF Group Slide 14
DMx connectivity to @ptitude Analyst
@ptitude Monitor
@ptitude AnalystClient
@ptitude Analyst
Client
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October 30, 2007 SKF Group Slide 15
Dual channel GX support
Multi-channel support for Microlog GX and DMx USB (Active Sync) only ROUTE based 2-channel and 3-channel (Triax) measurements Applications
Force, Couple and Overhung Rotor Unbalance
Eccentric Rotor
Bent Shaft
Angular and Parallel Misalignment
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October 30, 2007 SKF Group Slide 16
Two channel data display
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October 30, 2007 SKF Group Slide 17
Triax data display
Triaxial support for Microlog GX v2.0Triax displays