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Difference between revisions of "ORBIGate Phase Measurement"
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The phase measurement is used most commonly to position | The phase measurement is used most commonly to position an unbalance. A corrected result, based on the phase measurement should be given so it is able to locate the unbalance rapidly. This can be done using the slot in the shaft as a reference. | ||
First, we<nowiki>'</nowiki>ll go through the parameters influencing a phase measurement. A phase result is obtained as displayed in figure 1: '''It represents how late the signal (for a particular frequency) is seen by the sensor (for example a proximity probe) after the slot has passed by the keyphazor probe. '''The frequency considered here is the rotating speed (1X). | First, we<nowiki>'</nowiki>ll go through the parameters influencing a phase measurement. A phase result is obtained as displayed in figure 1: '''It represents how late the signal (for a particular frequency) is seen by the sensor (for example a proximity probe) after the slot has passed by the keyphazor probe. '''The frequency considered here is the rotating speed (1X). | ||
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Phase is used to compare the timing of two events in different signals. If an event occurs later in time than a reference event, then it lags the reference event. Similarly, if an event occurs before the reference event, then it leads the reference event. | Phase is used to compare the timing of two events in different signals. If an event occurs later in time than a reference event, then it lags the reference event. Similarly, if an event occurs before the reference event, then it leads the reference event. | ||
The convention used in most vibration measurement is to measure phase LAG with a '''positive number''', sometimes called ''positive phase lag''. On the opposite a usual mathematical definition would give a negative sign to a LAG and a positive sign to a LEAD. We<nowiki>'</nowiki>ll stay focus on the usual mechanical convention showing a LAG with a positive number. '''ORBIGATE uses the phase lag convention and gives a positive value for the phase lag.''' | |||
For example, let<nowiki>'</nowiki>s take the vibration signal shown in the figure below. The spike in the Keyphasor provides the timing reference. The event of interest is the first positive peak of the vibration signal that occurs '''after (to the right of)''' the Keyphasor event. Because the first positive peak occurs after the Keyphasor event, the time delay between the two events is referred to as the phase LAG. | For example, let<nowiki>'</nowiki>s take the vibration signal shown in the figure below. The spike in the Keyphasor provides the timing reference. The event of interest is the first positive peak of the vibration signal that occurs '''after (to the right of)''' the Keyphasor event. Because the first positive peak occurs after the Keyphasor event, the time delay between the two events is referred to as the phase LAG. | ||
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===Trigger Slope=== | ===Trigger Slope=== | ||
The phase value may slightly depend on the fall/rise trigerring condition. In ORBIGate this value can be selected as shown in figure 8. In some other system on the market this value is sometimes fixed. In the ADRE system it is fixed to "fall". | The phase value may vary slightly depend on the fall/rise trigerring condition. In ORBIGate this value can be selected as shown in figure 8. In some other system on the market this value is sometimes fixed. In the ADRE system it is fixed to "fall". | ||
[[Image:ORBIGatePhasePolar_17.png|framed|none]] | [[Image:ORBIGatePhasePolar_17.png|framed|none]] | ||
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==Phase display== | ==Phase display== | ||
===Overview grid=== | ===Overview grid=== | ||
The phase value of | The phase value of order one is shown in the grid in the column (1X Ph) | ||
[[Image:ORBIGatePhasePolar_19.png|framed|none]] | [[Image:ORBIGatePhasePolar_19.png|framed|none]] | ||
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===Bode Diagram=== | ===Bode Diagram=== | ||
* In the Bode diagram, it is possible to show the phase on several phase | * In the Bode diagram, it is possible to show the phase on several phase rotations: For that, a right click should be done on the Bode diagram and choose the number of rotations. By default it is 1, giving 0/360°. | ||
[[Image:ORBIGatePhasePolar_20.png|framed|none]] | [[Image:ORBIGatePhasePolar_20.png|framed|none]] | ||
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* The phase can be shown in several types of diagrams: Overview grid, Vumeter, Bode and Polar. | * The phase can be shown in several types of diagrams: Overview grid, Vumeter, Bode and Polar. | ||
* ORBIGate uses the lag convention | * ORBIGate uses the lag convention. | ||
* The phase lag gives a positive value of the phase in ORBIGate | * The phase lag gives a positive value of the phase in ORBIGate. | ||
* It is possible to choose (in the preferences) the convention between -180°/180° and 0/360°. By default it is 0/360°. | * It is possible to choose (in the preferences) the convention between -180°/180° and 0/360°. By default it is 0/360°. | ||
* In the Bode diagram, it is possible to show the phase on several phase rotation: for that it is necessary to right click on the Bode diagram and choose the number of rotations. | * In the Bode diagram, it is possible to show the phase on several phase rotation: for that it is necessary to right click on the Bode diagram and choose the number of rotations. | ||
* It is possible to choose to trigger the phase count on the rise or the fall of the keyphazor pulse. By default it is Fall. | * It is possible to choose to trigger the phase count on the rise or the fall of the keyphazor pulse. By default it is Fall. | ||
* In the polar diagram, the phase rotates in the opposite direction of the machine rotation. | * In the polar diagram, the phase rotates in the opposite direction of the machine rotation. | ||
* In the polar diagram, the 0° is shown as the position of the sensor (proximity probe, velocity probe or accelerometer) | * In the polar diagram, the 0° is shown as the position of the sensor (proximity probe, velocity probe or accelerometer). | ||
* In the polar diagram, the keyphazor position is shown as setup in the interface. | * In the polar diagram, the keyphazor position is shown as setup in the interface. | ||