NVGate Envelope analysis - Revision history

Lmagimel at 09:00, 26 November 2024

2024-11-26T09:00:03Z

← Older revision		Revision as of 11:00, 26 November 2024
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			[[category:WikiOros]]
	Using the envelope analysis for roller bearing defect detection.		Using the envelope analysis for roller bearing defect detection.

LDesmet: English edits

2020-06-18T21:10:43Z

English edits

Lmagimel at 13:07, 29 April 2020

2020-04-29T13:07:49Z

← Older revision		Revision as of 15:07, 29 April 2020
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	Using the envelope analysis for roller bearing defect detection.		Using the envelope analysis for roller bearing defect detection.

	~~'''~~Objective:~~'''~~		===Objective:===

	Abnormal vibrations were detected on a speed reducing gear box. We proceed to the diagnostic of the machine. A default in the roller bearing is suspected. An accelerometer is positioned close to the bearing and connected to the OR3X analyzer.		Abnormal vibrations were detected on a speed reducing gear box. We proceed to the diagnostic of the machine. A default in the roller bearing is suspected. An accelerometer is positioned close to the bearing and connected to the OR3X analyzer.
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	[[Image:Envelope_01.png\|framed\|none]]		[[Image:Envelope_01.png\|framed\|none]]

	~~'''~~Necessary equipment:~~'''~~		===Necessary equipment:===

	~~OROS analyzer~~

			OROS analyzer with NVgate Software
	In this example we are analysing the time signal file recorded with the analyzer. The office mode of NVGate is used.		In this example we are analysing the time signal file recorded with the analyzer. The office mode of NVGate is used.

	~~'''~~Description:~~'''~~		===Description:===

	The first step consists in the traditional FFT spectrum analysis of the signal in the complete frequency bandwith (0-20 kHz).		The first step consists in the traditional FFT spectrum analysis of the signal in the complete frequency bandwith (0-20 kHz).
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	----		----

	~~<font size~~ = ~~"4">'''~~Step 1: Traditional Spectrum Analysis~~'''</font>~~		===Step 1: Traditional Spectrum Analysis===

	In a first step, we determinate the spectrum obtained from the accelerometer signal. The signal is considered on a frequency band 0-20 kHz.		In a first step, we determinate the spectrum obtained from the accelerometer signal. The signal is considered on a frequency band 0-20 kHz.

	[[Image:Envelope_02.png\|framed\|none]]		[[Image:Envelope_02.png\|framed\|none\|Figure 1: Spectrum Analysis]]

	~~==- Spectrum Analysis==~~
	With the cursor we can detect two resonance domains. The first resonance is detected around 4.3 kHz and the second one around 13.3 kHz.		With the cursor we can detect two resonance domains. The first resonance is detected around 4.3 kHz and the second one around 13.3 kHz.

	----		----

	~~<font size~~ = ~~"4">'''~~Step 2: Zoom Analysis~~'''</font>~~		===Step 2: Zoom Analysis===

	The traditional approach is to use a zoom analysis around 4.3 and 13.3 kHz in our case. In the NVGate software define the settings of the FFT Zoom by:		The traditional approach is to use a zoom analysis around 4.3 and 13.3 kHz in our case. In the NVGate software define the settings of the FFT Zoom by:
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	* defining the center frequency of the zoom at 4.3 kHz in a first time. We can also use the drag and drop action to place the center frequency in the averaged spectrum window.		* defining the center frequency of the zoom at 4.3 kHz in a first time. We can also use the drag and drop action to place the center frequency in the averaged spectrum window.

	[[Image:Envelope_03.png\|framed\|none]]		[[Image:Envelope_03.png\|framed\|none\|Figure 2 - Zoom Analysis Settings]]


	~~''Figure 2 - Zoom Analysis Settings''~~

	Now the Zoomed averaged spectrum window can be displayed (Figure 3).		Now the Zoomed averaged spectrum window can be displayed (Figure 3).

	[[Image:Envelope_04.png\|framed\|none]]		[[Image:Envelope_04.png\|framed\|none\|Figure 3- Zoom Analysis]]


	~~==Figure 3- Zoom Analysis==~~
	The zoomed spectrum helps us to have a better resolution around the carrier frequency at which the signal is demodulated. For doing this kind of analysis we can use the side band markers. Actually a typical signal spectrum can be noticed as it usually has a central frequency line with lower amplitude side lines, as shown on the figure below:		The zoomed spectrum helps us to have a better resolution around the carrier frequency at which the signal is demodulated. For doing this kind of analysis we can use the side band markers. Actually a typical signal spectrum can be noticed as it usually has a central frequency line with lower amplitude side lines, as shown on the figure below:

	[[Image:Envelope_05.gif\|framed\|none]]		[[Image:Envelope_05.gif\|framed\|none\|Figure 4- Envelope Analysis]]


	~~==Figure 4- Envelope Analysis==~~

	If we see such a spectrum shape then it means we can start the envelope analysis.		If we see such a spectrum shape then it means we can start the envelope analysis.
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	In the NVGate software, we use the side band markers in the Zoomed averaged spectrum window to identify the modulation frequency (Figure 5).		In the NVGate software, we use the side band markers in the Zoomed averaged spectrum window to identify the modulation frequency (Figure 5).

	[[Image:Envelope_06.png\|framed\|none]]		[[Image:Envelope_06.png\|framed\|none\|figure 5: Side band markers in the Zoomed averaged spectrum window around 13.3 kHz]]


	~~==- Side band markers in the Zoomed averaged spectrum window around 13.3 kHz==~~

	We can suspect a modulation frequency of 148.4 Hz which exactly corresponds to the value of the inner bearing race defect frequency provided by the manufacturer of the ball bearing.		We can suspect a modulation frequency of 148.4 Hz which exactly corresponds to the value of the inner bearing race defect frequency provided by the manufacturer of the ball bearing.
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	----		----

	~~<font size~~ = ~~"4">'''~~Step 3: Envelope Analysis~~'''</font>~~		===Step 3: Envelope Analysis===

	The envelope mode is activated by choosing a zoom factor (already done in our example) and checking the box "Envelope" (Figure 6).		The envelope mode is activated by choosing a zoom factor (already done in our example) and checking the box "Envelope" (Figure 6).
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	The Envelop trigger and the Envelope spectrum windows can now be displayed (number 4 of the Figure 6).		The Envelop trigger and the Envelope spectrum windows can now be displayed (number 4 of the Figure 6).

	[[Image:Envelope_07.png\|framed\|none]]		[[Image:Envelope_07.png\|framed\|none\|Figure 6- Envelope and Zoom Analysis at 13.3 kHz]]

	''~~Figure 6- Envelope and Zoom Analysis at 13.3 kHz~~''		''''

	Five shocks per revolution are identified in the Envelope trigger window obtained after the signal demodulation (number 4 of the Figure 6).		Five shocks per revolution are identified in the Envelope trigger window obtained after the signal demodulation (number 4 of the Figure 6).
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	[[Image:Envelope_08.png\|framed\|none]]		[[Image:Envelope_08.png\|framed\|none]]
			===Step 4: Analysis of the demodulated signal===
	~~<font size~~ = "4~~">'''Step 3~~: Analysis of the demodulated signal~~'''</font>~~

	From the envelope signal window we can also detect the two characteristic frequencies previously found (Figure 8):		From the envelope signal window we can also detect the two characteristic frequencies previously found (Figure 8):

	[[Image:Envelope_09.png\|framed\|none]]		[[Image:Envelope_09.png\|framed\|none\|Figure 8 – Zoom display on the envelope trigger window]]

	''Figure 8 – Zoom display on the envelope trigger window''

Lmagimel at 13:02, 29 April 2020

2020-04-29T13:02:19Z

← Older revision		Revision as of 15:02, 29 April 2020
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	~~==SUBJET:~~ Using the envelope analysis for roller bearing defect detection~~<br>==~~		Using the envelope analysis for roller bearing defect detection.

	'''Objective:'''		'''Objective:'''

Lmagimel: Created page with "==SUBJET: Using the envelope analysis for roller bearing defect detection
== '''Objective:''' Abnormal vibrations were detected on a speed reducing gear box. We proceed t..."

2020-04-29T13:01:32Z

Created page with "==SUBJET: Using the envelope analysis for roller bearing defect detection == '''Objective:''' Abnormal vibrations were detected on a speed reducing gear box. We proceed t..."

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==SUBJET: Using the envelope analysis for roller bearing defect detection ==

'''Objective:'''

Abnormal vibrations were detected on a speed reducing gear box. We proceed to the diagnostic of the machine. A default in the roller bearing is suspected. An accelerometer is positioned close to the bearing and connected to the OR3X analyzer.

[[Image:Envelope_01.png|framed|none]]

'''Necessary equipment:'''

OROS analyzer

In this example we are analysing the time signal file recorded with the analyzer. The office mode of NVGate is used.

'''Description:'''

The first step consists in the traditional FFT spectrum analysis of the signal in the complete frequency bandwith (0-20 kHz).

The zoom analysis is used in the second step. The third step describes the envelope analysis.

Finally, we will also proceed to the analysis of the demodulated signal in the fourth step

----

'''Step 1: Traditional Spectrum Analysis'''

In a first step, we determinate the spectrum obtained from the accelerometer signal. The signal is considered on a frequency band 0-20 kHz.

[[Image:Envelope_02.png|framed|none]]

==- Spectrum Analysis==
With the cursor we can detect two resonance domains. The first resonance is detected around 4.3 kHz and the second one around 13.3 kHz.

----

'''Step 2: Zoom Analysis'''

The traditional approach is to use a zoom analysis around 4.3 and 13.3 kHz in our case. In the NVGate software define the settings of the FFT Zoom by:

* setting a zoom factor of 16.
* defining the center frequency of the zoom at 4.3 kHz in a first time. We can also use the drag and drop action to place the center frequency in the averaged spectrum window.

[[Image:Envelope_03.png|framed|none]]

''Figure 2 - Zoom Analysis Settings''

Now the Zoomed averaged spectrum window can be displayed (Figure 3).

[[Image:Envelope_04.png|framed|none]]

==Figure 3- Zoom Analysis==
The zoomed spectrum helps us to have a better resolution around the carrier frequency at which the signal is demodulated. For doing this kind of analysis we can use the side band markers. Actually a typical signal spectrum can be noticed as it usually has a central frequency line with lower amplitude side lines, as shown on the figure below:

[[Image:Envelope_05.gif|framed|none]]

==Figure 4- Envelope Analysis==

If we see such a spectrum shape then it means we can start the envelope analysis.

In the NVGate software, we use the side band markers in the Zoomed averaged spectrum window to identify the modulation frequency (Figure 5).

[[Image:Envelope_06.png|framed|none]]

==- Side band markers in the Zoomed averaged spectrum window around 13.3 kHz==

We can suspect a modulation frequency of 148.4 Hz which exactly corresponds to the value of the inner bearing race defect frequency provided by the manufacturer of the ball bearing.

From the shape of this spectrum we can also see there is a modulation phenomenon. This is why we are going to proceed to the envelop analysis to check the demodulated signal and its spectrum.

----

'''Step 3: Envelope Analysis'''

The envelope mode is activated by choosing a zoom factor (already done in our example) and checking the box "Envelope" (Figure 6).

The Envelop trigger and the Envelope spectrum windows can now be displayed (number 4 of the Figure 6).

[[Image:Envelope_07.png|framed|none]]

''Figure 6- Envelope and Zoom Analysis at 13.3 kHz''

Five shocks per revolution are identified in the Envelope trigger window obtained after the signal demodulation (number 4 of the Figure 6).

We are using the Harmonic markers in the Envelope spectrum window to detect the modulation frequency that is significant of the defect in the gear box. In our case we confirm that the frequency at 148.4 Hz is the modulation frequency (Figure 7).

[[Image:Envelope_08.png|framed|none]]

'''Step 3: Analysis of the demodulated signal'''

From the envelope signal window we can also detect the two characteristic frequencies previously found (Figure 8):

[[Image:Envelope_09.png|framed|none]]

''Figure 8 – Zoom display on the envelope trigger window''