orbits and scl presentation

8/13/2019 Orbits and SCL Presentation

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October 30, 2007 SKF Group Slide 0


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3Orbits and Shaft Centerline

2014-01-29 SKF Slide 1 [Code]SKF [Organisation]


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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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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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Orbit and Shaft Centerline


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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.


7/18October 30, 2007 SKF Group Slide 6

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

Gap

Time

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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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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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Shaft Centerline (SCL)

Speed plotted along thestartup center line.

Cursor indicateseccentricity value


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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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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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Vector & Waveform setup

Vector compensation issupported for the first threevectors 1x, 2x, 3x.

Waveform compensation isalso supported.


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Triax POINT setup

Requires triax sensorconnected to GX(version 2.0 or higher)


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DMx connectivity to @ptitude Analyst

@ptitude Monitor

@ptitude AnalystClient

@ptitude Analyst

Client


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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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Two channel data display


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Triax data display

Triaxial support for Microlog GX v2.0Triax displays

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