Section 11 Advanced Sampling

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Advanced Sampling Page 1

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I. nX Vector

A) nX Vector Configuration

In addition to 1X and 2X tracking filters, you can use nX Vector to track auser configured third component. N can have nonintegral values between

0.100 and 1.0 (in intervals of 0.025) or integral values between 1 and 15.

One nX Vector is configurable for each DAIU. Typical applications of the

nX vector are to track a particular frequency such as 0.5X from a rub, or a

higher order of running speed like 5X from vane passage frequency on a

pump. Differential Phase also uses the nX vector (see below).

Note: In order to acquire nX values below 0.200, a 208 firmware version of

1.02 is required.

You must set n in nX before you begin data acquisition. Configuration of

the nX Vector is done from the main Configuration dialog box.

Figure 1. Configuring the nX Vector


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B) Using nX With Plots

The nX Vector can be selected as the main variable in many plot

configurations. The example below shows an nX Trend. If the nX Vector

is an integer order of running speed (5X for example), nX phase angle willbe available for plotting along with amplitude.

Figure 2. nX Trend of 5X Component

Figure 3. Selecting nX Slow Roll Vector Compensation


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C) nX Vector Slow Roll Compensation

You can select Slow Roll compensation on most plots that have nX as a

main variable option. Be sure that you have selected nX Vectors from the

Edit Reference - Slow Roll Vector dialog box (see Section 6, EditingReference Data). Keep in mind that nX Slow Roll vector subtraction can be

performed only if the nX vector is an integer order of running speed.

II. Differential Phase

A) Using Differential Phase

Differential Phase allows relative phase measurement of nX vectors when

one of the channels is chosen as a reference. The system subtracts the

absolute nX phase lag angle of the reference from the absolute nX phase lag

angles of all the channels and then displays the difference in tabular list and

current values plots on a sample-by-sample basis. The reference has no

effect on other frequency components of real-time or saved data.

Though the nX Vector must be selected prior to sampling, Differential

Phase can be invoked either before or after sampling. Differential Phase is

configured from the main Configuration dialog box.

Figure 4. Configuring Differential Phase


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B) Differential Phase Configuration

To configure differential phase:

1) Choose DAIU 1 from the DAIU group box. The "n" value of thenX vector will be displayed in the text boxes of this group, as

specified in nX Vector Configuration.

2) Choose a Reference channel from channels 1 through 8.

3) Repeat Steps 1 and 2 for DAIU 2 and Channels 9 through 16 if you

are using a second DAIU.

4) Click Enable.

5) Press OK to confirm your settings and return to Configuration

dialog box. Or if you prefer, use one of the Go To push buttons

to exit; they will also confirm your differential phase configuration.

! T a b u l a r L i s t - D i f fe r e n t ia l P h a s e D is a b le d

! T a b u l a r L i s t - D if fe r e n t ia l P h a s e E n a b le d

n X V e c to r

n X V e c to r

R e fe r e n ce C h a n n e l

Figure 5. Differential Phase Example in Tabular List


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Three rules apply to Differential Phase channels:

1. The reference channel must be an active channel. (See Channel

Configuration.)

2. Select only one reference channel from each active DAIU.

3. The transducer for the selected channel cannot be a process

variable transducer.

Note: You can choose a channel that is associated with a Simulated

Keyphasor as a reference even though phase lag angle data from a

Simulated Keyphasor is unreliable. This is true because relative and not

absolute phase lag angles are subtracted from the data.

Use Disable to temporarily disable your Differential Phase setup. By

disabling the setup you can view data without using a reference channel.

III. Zoom Channels

A Using Zoom Channels

When enabled, Zoom Channels configures up to two channels per DAIU for

high resolution (3200 line) spectrums. Zoom Channels must be configured

prior to sampling.

The system takes longer to collect data for Zoom Channels than for

channels receiving data at normal resolutions. Use this formula to determine

the time it will take to collect data:

Time (sec) = 8192 / (FS X 2.56)

where FS is the frequency span. For example, if you set a frequency span of

50 Hz, the DAIU will take more than a minute to collect data in zoom mode.


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Figure 6. Half Spectrum Plot with Zoom Channel Enabled

B) Zoom Channels Configuration

Any channel can be configured as a zoom channel. The Zoom Channels

configuration is accessed through the main Configuration dialog box. Toconfigure zoom channels:

1) Find the channel you want to configure as a zoom channel using

the scrollbar if necessary.

2) Pick the checkbox of the channel(s) you want to configure as a

zoom channel.

!High Resolution 3200-Line Spectrums

!(2) Zoom Channels / DAIU

!(1) Zoom Channel / Channel Pair


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Figure 7. Zoom Channels Configuration

Zoom channel configuration must conform to these three rules:

1) Only active channels can be zoom channels.

2) Each DAIU can have two channels configured as zoom channels,

so you can have up to four zoom channels if you are using two

DAIUs.

3) Only one of the two channels in a channel pair can be configured

as a zoom channel. So if channel 3 is a zoom channel, channel 4

cannot be.

Caution: When zoom channels are enabled, spectrum plots can only be

displayed for the channels configured as zoom channels. Also,synchronous waveform plots cannot display direct data for zoom

channels. And, if only one zoom channel is configured with the

first keyphasor association, the second keyphasor association will

not collect any direct waveform data.


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C) Enabling and Disabling Zoom Channels

Use Disable to deactivate all zoom settings without deleting them. With

zoom channels deactivated, the system collects data at the standard

resolution set in Spectrum Sample Rate Configuration. You can reactivatezoom settings by pressing Enable Zoom.

IV. Trigger Event Sampling

A) Trigger Event Options

Use this dialog box to choose a trigger source and trigger threshold. A

trigger source is the type of event that starts data collection. A trigger

threshold is the level of the trigger source that starts the data collection.

Once a trigger event threshold requirement has been met, data acquisitionwill start and will continue according to the sampling scheme set in Sample

Mode configuration. There are five options which can be configured as a

trigger event. Only one trigger event can be configured at a time to

automatically start the data collection process in Store Enable. There is the

option to manually trigger (start) the data collection when you are in the

Store Enable menu.

Figure 8. The Trigger Event Configuration Dialog Box


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The most often used trigger source is Speed. The default setting of Over

100 and Under 60,000 initiates sampling as soon as the rpm of

Keyphasor 1 is between 100 rpm and 60,000 rpm after entering Store

Enable.

Over and Under setpoints of any trigger event can be configured and

saved with a database configuration for later use even if they are not

enabled.

B) Trigger On Speed Configuration

Select Speed as the trigger source and select Over Setpoint, Under

Setpoint, or both. Press the Configure button to bring up the Trigger

On Speed Configuration dialog box. Enter a level as an integer between

100 and 60,000 (rpm) in the Over edit box, the Under edit box, or both.

Sampling will begin when machine speed moves above or below the

enabled setpoints.

Figure 9. Configuration Example for Trigger on Speed


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C) Trigger on Time Configuration

To start collecting data at a preset date and time, select Time as the trigger

source and press the Configure button to bring up the Trigger on Time

Configuration dialog box. Enter the date and time you wish to start dataacquisition in these six edit boxes. The time must be a future event. You

will receive an error message if the start time you select is earlier than the

computer clock time.

Figure 10. Trigger On Time Configuration Example

The settings for Trigger on Time must be within these ranges:

Hour: 0-23

Minute: 0-59

Second: 0-59

Day: 1-31

Month: 1-12

Year: 1980-2037


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D) Trigger On Amplitude Configuration

Use this dialog box to start collecting data when the amplitude of a trigger

moves above or below a set amplitude. Each active channel can have one or

two trigger thresholds or setpoints. Over specifies an amplitude abovewhich data acquisition will begin and Under specifies an amplitude below

which data acquisition will begin. "Over" and Under" edit boxes are

available for each of the 16 channels. The second group of eight channels is

accessible by using the scrollbar.

Select Amplitude as the trigger source, then select "Under setpoint"

and/or "Over setpoint" check boxes in the Trigger On group. Press the

Configure push button to bring up the Trigger on Amplitude

Configuration dialog box.

Figure 11.Trigger On Amplitude Configuration Example


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To configure trigger on amplitude:

1) Select the type of amplitude from the Amplitude Trigger Source

group: Direct, 1X, 2X, nX, or DC Gap/Process

Variable. The n in nX was specified in nX VectorConfiguration.

2) Check the Trigger checkbox for the channels desired and enter

over and under setpoints in the selected channel edit boxes.

The following rules apply to trigger on amplitude:

a) TorXimitor and Process Variable transducers cannot trigger

on Direct, 1X, 2X, or nX.

b) Acceptable transducer types for DC Gap/Process Variable in

the Amplitude Trigger Source group are displacement,

TorXimitor, or Process Variable.

c) The Under and Over set points must lie within

configured Full Scale Ranges for each channel and variable.


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E) Trigger On Phase Configuration

Use this dialog box to start collecting data when the phase lag angle moves

outside the Over and Under setpoints. Each active channel can use

either or both phase lag angle setpoints. Over specifies a phase abovewhich data acquisition will begin and Under specifies a phase below

which data acquisition will begin. "Over" and "Under" values are available

for each of the 16 channels. The second group of eight channels is

accessible by using the scrollbar.

Figure 12. Trigger On Phase Configuration Example


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To configure trigger on phase:

1) Select Phase as the trigger source.

2) Check either or both of the Over Setpoint and Under Setpointcheckboxes.

3) Press the Configure push button to bring up the Trigger On

Phase Configuration dialog box. Choose 1X, 2X, or nX

from the Trigger Source group. Note: Specify the "n" in nX Vector

configuration; n must be an integer multiple of running speed to

have an absolute phase angle.

4) Check the Trigger checkbox for one or more channels and

specify a range in degrees for each selected channel. Sampling will

begin when the phase angle for a particular channel goes outside its

range. Minimum and maximum values for setpoint edit boxes are

0 and 359.

A channel may not be available if the channel associated with the checkbox

is not active (see Channel Configuration), or the channel associated with

the checkbox was one you assigned a Simulated Keyphasor during Channel

Configuration (an external Keyphasor is required for absolute phase

measurements).


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F) Trigger On Contact Configuration

Figure 13. Trigger On Contact Configuration

Use this dialog box to use remote relays connected to the DAIU to start

collecting data. Each DAIU has a terminal block with four connections that

can be connected to a remote relay: Earth Gnd, Lo Volt, Return, and Hi

Volt. The Lo Volt handles 5V to 30V. The Hi Volt handles 90V to 240V.

WARNING: Do not put high voltage in the low voltage circuit.

To use a remote relay to signal data collection:

1) Select Contact as the trigger source, then press the Configure

command button to bring up the Trigger On Contact

Configuration dialog box.

2) Select Normally Closed if you want data acquisition to startwhen the relay is open, or:

Select Normally Open if you want data acquisition to start when the

relay is closed.


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V. Sample Management

A) Manual Samples

Although you have a buffer of 2560 vector samples (256 waveformsamples) to work with, it is good practice to have extra samples available

for manual sampling if needed. You never know when a sudden upset

might occur which you will want to document. If you are sampling at

regular delta time intervals, a few manual samples may be needed to ensure

such an intermittent event gets captured.

Note: Versions of ADRE for Windows before 4.60 have a maximum of

1280 vector samples (128 waveform samples) to work with instead of 2560.

Make sure you know which version you are using before assuming your

limit. Click Help from the main menu bar, then About Adre to

double check which version you are using.

Though each manual sample uses only one vector sample for each

waveform sample, the number of samples you set aside should still be based

on a 10:1 ratio of vector to waveform samples:

Manual Samples (Vectors) = Number of Waveform Samples x 10

Example:You want to set aside 30 manual samples for direct waveforms and

spectrums.

Solution:

Manual Samples = 30 Waveform Samples x 10

= 300 Vector Samples

2560 - 300 = 2260

Set Sample Mode parameters to use no more than 2260 Vector Samplesduring normal programmed (delta time/delta rpm) data acquisition.


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Note: Normally you will not need to use more than 400 samples or so for a

typical data acquisition exercise (see Data Acquisition Configuration

in Section 5). If Sample Mode parameters are set conservatively to

acquire data with a reasonable sample density (approximately 400

samples for a startup or shutdown), there will be plenty of unusedsamples available for manual samples if needed.

B) Vector / Waveform Sample Ratio

Manual samples will skew the normal 10:1 ratio of vector samples to

waveform samples to a smaller ratio. When this happens, care must be

taken to make sure there are enough samples remaining to capture the data

you need. Though the DAIU Control Panel displays the number of samples

both used and remaining, the actual number of usable vector samples

remaining may be significantly less than the displayed value because

sampling will stop when all waveform samples have been used. See

example below. If you have turned on Continuous Data Collection in the

Preferences, the data will be saved to disk when a sample limit is reached

and then ADRE!for Windows will recommence acquiring data. However,

the computer is not acquiring data while it is saving the run to disk so you

will have a hole in your data base and the data run will be split between

different databases.

Two good rules of thumb to remember when using Manual Samples are:

1) Usable Vector Samples Remaining = Waveform Samples

Remaining x 10

2) Set Sample Mode Parameters Conservatively to start with!!


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Figure 14. Sample Limits Dialog Box Showing Depleted Waveform Samples and

End of Sampling

C) Sample Mode Adjustments During Data Acquisition

Sometimes you may need to make adjustments to your sample mode

parameters during sampling to conserve remaining samples. You can make

the following changes from the DAIU Control Panel:

Delta Time

1) Enable/Disable

2) Adjust Delta Time interval

Delta RPM

1) Enable/Disable2) Turn On or Off Increasing or Decreasing

3) Adjust Delta RPM interval

Keep in mind that sampling will be paused while you are making these

changes.

!!!!DONT LET THIS HAPPEN TO YOU!!

!!!!Set Sample Mode Parameters CONSERVATIVELY


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VI. Non-Standard Data Acquisition

A) Steady State Trending + Trip / Coastdown Coverage

The following example is one possible scenario where you may employboth Delta RPM and Delta Time simultaneously.

Example:

Lets say you need to automatically collect trend data overnight (7:00

PM to 7:00 AM) on a 12,000 rpm compressor. You want to

automatically capture a coastdown if the machine train is somehow

tripped any time during the night. Assume no manual samples.

Solution:

In Sample Mode:

- Enable Delta Time andDelta RPM

- 600 Sample records dedicated to potential shutdown

- 1960 Sample records dedicated to steady state trend

Delta RPM =(12,000rpm-100rpm) / 600 =19.8 rpm

Monitoring Time = 12 hours x 60 minutes/hour = 720 minutes

Delta Time = 720 minutes / 1960 records = 0.37 minutes/record =23 seconds

Be conservative:

- Set Delta RPM 25 rpm Decreasing only

- Set Delta Time 30 seconds


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B) Speed Oscillations

For startups on machine trains where speed fluctuations are common, it is

easy to use up all 2560 samples prematurely because of the total Delta Rpm

that takes place. There are several different strategies to use to avoid usingup your samples this way:

1) Set Delta Rpm for Increasing only.

- or -

2) Set a large Delta Rpm interval and use both Increasing and

Decreasing.

- or -

3) Set Delta Rpm for Increasing only with a conservative Delta

Rpm interval. Set Delta Time with a conservative (long) interval

so that occasional data will be taken during hold points.

C) Fast Startups/Shutdowns

The most frequent sampling problems when taking data during rapid

machine speed changes are tracking filter response time and spectrum

sampling speed. A slow tracking filter may miss the full extent of amplitude

and phase changes if the changes occur quickly. A high resolution spectrum

may not have enough time at a particular speed to accurately sample a

spectrum. Sampling speed can usually be improved, but the tradeoff ispoorer resolution. Still, a poorer resolution spectrum is better than no

spectrum at all. To speed up tracking filter response time and spectrum

sampling:

1) Use the 120 rpm bandwidth filter (set in Channel Configuration).

This is a much faster tracking filter than 12 rpm bandwidth.

2) Use Delta RPM only. Delta RPM sampling is potentially much

faster than even the smallest Delta Time interval (0.1 seconds).

3) Do not use Zoom Channels.

4) Set Spectral Lines to 200 or even 100 to speed up spectrum

sampling.

5) Increase the Spectrum Frequency Span setting.


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D) Repeating Data Collection

You can configure ADRE to continue collecting data even after a database

fills up. From the File menu, select Preferences to bring up the

Preferences dialog box.

Figure 15. Preferences dialog box

Select the Repeating Data Collection checkbox to configure the system to

continue collecting data after the first database fills up and is saved to disk.

If you select the Reset Trigger checkbox, after a database is filled and

saved to disk, the system will reset the data acquisition trigger. If the

machine conditions meet the triggered criteria that you set, data collection

will resume automatically. If the machine conditions do not meet the

triggered criteria, ADRE will wait until data acquisition is triggered before

collecting any more data.

For example, if you configured your system to trigger when the machinegoes above 350 rpm, to sample with delta time every second, and you

selected Repeating Data Collection and Reset Trigger, the system will

begin collecting data when the machine increases above 350 rpm. The

database will then take a vector sample every second until the database is

full with 2560 vectors. At this point, ADRE will automatically save the

database and prepare to continue collecting data. Because you selected


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Reset Trigger, the system will see if the machine is still operating above

350 rpm. If the machine is above 350 rpm, data acquisition will be

triggered and ADRE will fill another database and save it. This process will

repeat over and over until the free space on the hard disk drops below 28.2

MB or the machine is below 350 rpm at the moment the system resets thetrigger.

Note: If you select Repeating Data Collection but do not check Reset

Trigger, once data acquisition is triggered the first time, it will

continuously collect and save databases (according to the sampling mode

parameters) until you manually stop it or until the free space on the hard

drive drops below 28.2 MB. This will occur even if the machine no longer

meets the triggered criteria.

Section 11 Advanced Sampling

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