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Test Sensor Cable for Faults


You can conduct a quick check onsite to ensure your cables are working. This in turn saves you diagnosing poor quality readings that result from a faulty cable. You can even avoid sending your instrument in for repair when it is actually the cable that is at fault.

QUESTION

My recordings have started showing lots of low frequency noise (ski slope) and few normal vibration peaks. Could my sensor cable be at fault?

ANSWER

Cables suffer a lot of abuse and do wear out. You can run a simple test on your instrument to detect whether a cable is faulty.

Test Cable — vbSeries Instrument

If you have upgraded to the latest release, you can display a live bias voltage graph of all connected channels and determine whether your sensors and cables are working correctly. To do this:


1. Secure your sensor so that it does not move — You could attach it to a machine that is not running or hold it with a clamp.
2. Press 2 or 7 Measure.
3. Use the navigation keys provided to scroll down and select Cable Test.
4. Press ✓ — The current voltage displays in real time.
5. Move the cable joints to determine whether there is an intermittent short:

• Consistent data (e.g. a straight line) indicates the cable is working correctly.
• Varying data (e.g. an irregular line) indicates there is a problem with the cable.

TIP: You can view the data that displays for a particular channel in more detail. To do this, press 9 to toggle and select the channel you wish to view > Press 0 to access an enlarged view of the data.

NOTE: You can run a cable test for any standard sensor that is supported by your instrument, including accelerometers, velocity sensors, and proximity probes.



Functioning cable connected to vbSeries Instrument



Faulty cable connected to vbSeries Instrument

Test Cable — vbX000 Instrument

To test a cable on a vbX000 instrument:

1. Place the accelerometer in a low-vibration location.
2. Select the Waveform Quick Setup option > Press 0 — Custom Setup.
3. Set the following parameters. 

• Mode — Acceleration.
• Duration — 1000 ms.
4. Press 0 — Display Options.
5. Press 7 > Set the Acceleration Max to 10 m/s2 (1 g).
6. Press ENTER to continue.7. Press ^ to save your custom settings.
8. Tap the end of the accelerometer with your finger — The instrument screen should display a trace to verify that the sensor is working.
9. Gently flex the cable, particularly at the end connectors and around the break-free connector. You should see small signals from the movements of the sensor. If you see dramatic swings, your cable has an intermittent contact and should be replaced.



Functional cable connected to vbX000



Faulty cable connected to vbX000