How Do I Connect an Ultraprobe 2000 to a vbX Instrument?
QUESTION
How do I connect a UE Systems Ultraprobe 2000 to a vbX instrument and analyze data from it?
ANSWER
The intention of this application note is to explain and assist with the use, set-up, and analysis of data that is available from the UE Systems Ultraprobe 2000 instrument.
The UE Systems Ultraprobe is an ultrasonic inspection tool that can be used in predictive maintenance. It is capable of detecting frequencies between 20 kHz and 100kHz. This makes it an excellent tool to be used in conjunction with the Commtest vbTM instrument. The most likely use of this technology would be as an additional analysis tool with the data collector when ultrasonic or bearing frequencies need to be detected and analyzed.
It must be emphasized that the values obtained from the output jack of this device are not scalable; and therefore at this time cannot be trended. However using the powerful analysis capabilities of the vb data collector, both the time waveform and the spectrum can be analyzed; thereby determining the cause of the machine problem.
The output of the Ultraprobe is a heterodyned output, which gives it a similar capability to acceleration high frequency energy spikes that are detected with enveloping. However, there would be little point in using these capabilities as a measurement parameter, as the fault frequency signal has already been processed by the Ultraprobe. The most likely parameter setup would be acceleration, and scaling may have to be log or dB scale if signal levels are extremely low.
1. Hardware requirements.
• Commtest vb instrument
• Ultraprobe 2000
• Cable UE-MP-BNC-2 from UE Systems.
2. Hardware setup.
• Turn on the vb and go to the Main Menu screen.
• Press "0" for Options.
• Press "5" for Sensor Setup.
• Press "6" for Change Sensor.
• Press "4" for Create New Sensor.
• Choose settings in the Sensor Screen as shown in Figure 1.
• Be sure that Drive Current is switched to OFF.
Figure 1. Sensor Setup
Store these settings so that Ultrasonics is a choice in your Sensors screen, as shown in Figure 2.
Figure 2. Sensors Available
3. Analyzing the Signal.
As mentioned earlier, the output of the Ultraprobe is a heterodyned output and is scaled by the user turning a potentiometer; thus, there will not be true output sensitivity from this device. However, we are only using it as a high frequency detection tool. Simply think of it as a different sensor and another ‘tool'.
The best way to analyze the output of the Ultraprobe is to use the Off-Route (Measure) capability of the vb instrument.
At the vb Main Menu, press "2" for Measure and then choose "6" for Spectrum/Waveform. Now set up a measurement as shown by Figure 3.
Figure 3. Measurement Setup
Note that we have 3200 lines of resolution, with an Fmax of 60 kCPM and an Fmin at 180 CPM. Linear averaging is set at 4, with a Hanning window.
It must be emphasized that we are now expecting to see bearing related frequencies without the influence of the lower rotational frequencies.
This is particularly important in situations that exist when a large amount of energy may be created in low speed applications due to looseness, as this is often a characteristic of the machine or the process. This energy may have the effect of masking the side-band information that allows us to analyze and determine bearing and gear related problems.
Remember that Bearing Fault Frequencies are not pure integer multiples of the rotational frequency, but are mathematically calculated from bearing specification data sheets and software.
Some advantages of using this method of detection and analysis are stated below:
1. Use the Ultraprobe for a quick look tool for bearing detection and then confirmation using the vb instrument.
2. Very effective on slow speed machines.
3. Unlike accelerometers when you use longer probes or stingers you do not lose the signal.
4. Extremely sensitive.
For more information about UE Systems contact:
UE Systems Inc., 14 Hayes Street, Elmsford, New York 10523 USA.
Toll Free: (800) 223-1325, Telephone (914) 592 1220 Fax (914) 347 2181.
Email: ue@att.net
Internet: http://www.uesystems.com
Practical use of the vb Series instrument and the Ultraprobe 2000
Here is an example a bearing condition on a machine having 2 identical bearings on a shaft running at approximately 1000 RPM. (Note: Actual screen captures presented here are for illustration purposes only; they are not from a vb instrument.)
Let's first take a look at the good bearing on the right side.
Right side bearing spectrum
Figure 4. Spectra From Good Bearing
Note the low amplitudes, with maximum of 0.065 gPk. The units are arbitrary. There is some evidence of harmonics at 9000 CPM which probably relates to speed control.
Now, let's turn our attention to the other side.
Left side bearing spectrum
Figure 5. Spectra From Defective Bearing
Here we see maximum amplitude at 2.5gPk with the same gain setting on the Ultraprobe. The Non Harmonic Bearing frequencies are all evident throughout the spectrum.
Summary
The use of this system does not replace any other bearing detection system; it is yet another diagnostic tool that gives positive information about bearing deterioration and failure. Quantitative measurements are possible as long as the gain setting is stored with the data to ensure that comparisons can be made.
Commtest Ascent® software can store the data collected either in the form of screen shots from the vbScreenCapture utility program or in a dynamic format that is either route data or unscheduled data.