Acoustics replacing vibration analysis..???

[sasuan]

I am assigned to evaluate a new program at our plant. Use of Acoustics for detecting vibration, over/under lubrication and arcing in transformers. We have a sound vibration analysis program for all rotating equipments already set in. Does the acoustics /ultrasound technology help any better than the vibration analysis?? Also, how useful is this technology in detecting lubrication problems and arcing. Thanks in advance.

 

[electricpete]

First off - I think you would do better to post this in the Mechanical Acoustics/Vibration engineering forum.

On the rotating equipment end, if you use vibration effectively looking at some early-warning signals for rolling element bearing problems (peak time waveform, Entek's "spike energy", CSI's "peakvue", SKF's "enveloped acceleration"), than you already have the ability to detect rolling element defects even before they would show up as visible damage on the race. Usually we see them and watch them on vibratin for awhile before we decide to call them. Detecting them earlier doesn't buy anything. Likewise lubrication problems can show up if you know what you're looking for. Also note bearing housing temperature is an effective means to monitor greased lubrication of bearings. We are not a believer in listening while you lubricate... too many downsides.... a while 'nother discussion. We use OEM-type recommendations to add a specific quantity at a controlled interval.

Transformers - DGA is your best tool for internal faults. Vibration can watch the pump and fan bearings if accessible. Acoustic may have a slight benefit for large transformer where you can't get to all the fans, but let's be realistic... one or two transformer fans are not critical to operation of the transformer. You might be able to detect various corona on the exposed external surfaces (that wouldn't show up in DGA because they are external). Once again I don't see a big benefit. I can hear a lot of different buzzing walking through a switchyard without the benefit of enhanced acoustic detection... usually I ignore it... what good if I can identify 10x as many buzzing places. Also there is infrared... if corona tracking proceeds to the point that it causes noticeable temperature changes on insulators than it is probably a problem worthy of attention.

We use dga and doble testing and infrared for our transformers, vib and lube oil for our rotating equipment, no kind of acoustics. I haven't found them necessary for reasons I've identifed above. Just my opinion.

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