Many problems associated with electrical inspections are often related to connections, such as with crimping, stripping or improper torque. Loose connections can manifest as sources of vibration or resistance. For this reason, it is often advisable to utilize both Infrared and Ultrasound technologies when inspecting electrical equipment.

While these problems can be spotted with an infrared camera, (SEE OUR WEBSITE FOR EXAMPLES) there are many instances in which they can be overlooked, such as when a connection is beyond line of sight, or if there is no detectable temperature differential. A loose connector will often have an associated vibratory motion, which can be heard with an ultrasound detector.

The sound of looseness often resembles that of corona or tracking. While a little experience will enable an inspector to determine which sound is looseness versus those that are not, a spectral analysis will quickly clarify any confusion. This can be performed with a vibration analyzer connected to an Ultraprobe or by recording the sound and downloading it into spectral analysis software. We have more details if you're interested.

Corona and tracking will have distinct harmonics of heterodyned 50 Hz, with some low-level frequency information between spikes. Looseness typically will reflect harmonics other than the heterodyned 50 Hz, usually 25 Hz with very little frequency information between spikes. The key to action is simple. If you hear a sound when none should exist, it requires further investigation. Whether that means opening up an enclosure to inspect visually or with an infrared camera, or to analyze the sound pattern, a diagnosis must be made to determine a course of action.

Caution should always be taken before opening any electrical equipment. Always think of your own safety. Standard procedures usually require de-energizing equipment before opening. However, there are times when it may be necessary to open electrical equipment while it is energized. The potential for injury lurks behind anything that is closed. For this reason, it is a good idea to listen with your Ultraprobe before you attempt to open anything live. Should there be any activity going on such as arcing or tracking, you will hear it.

Using the scanning module with a rubber focusing probe, scan all the seams and vents. If it is totally closed with no air path to carry the sound, use the contact probe at 25 kHz and probe around the surface.

Should you need to perform a "Peak Hold" inspection but do not want to change from the Real Time inspection mode, all you have to do is use the bargraph display. There is a vertical line that acts as a Peak Hold indicator. While the bar graph is intended to provide a visual indication of intensity swings in a manner similar to the analog display on the analog models, the vertical line will freeze in the highest sound level location until another "higher" sound comes along.

Arvin Meritor Heavy Vehicle Braking Systems' plant in Cwmbran is a fair size. It is divided into four areas and engineers have been very successful in detecting compressed air leaks in each of the areas using their Ultraprobe 550.

Stephen Phillips (Production Engineer) writes, "We have completed a survey of the site and identified potential savings of £40,750 and carried out repairs to an estimated value of £13,250. We have agreed that each area will have the instrument for one month to carry out a survey and repair any resultant leaks. This means that the site will be surveyed four times a year."

Stephen continues, "I have trained a number of tradesmen on the shop floor in the use of the instrument and after some initial scepticism, e.g. "I don't need an instrument to tell me there's an air leak", everyone has been impressed with how easy the Ultraprobe is to use. The main direction of the training has been in estimating the size of the leak and on the importance of filling in the report sheets, and of course on carrying out the repairs."

Incidentally the web site has charts detailing the cost of steam, compressed air and nitrogen leaks.

It's always good to receive your feedback, on any product we have sold or rented. If you have a success story that you would like to share with others in a future newsletter, please get in touch. Maybe see you at Maintec (12-14th March). We're on stand A16.

It is always good to receive your feedback on any product we have sold or rented. If you have a success story that you would like to share with others in a future newsletter, then please do get in touch.

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