Electrical Inspection with Ultrasound

Ultrasound inspection can be performed at all voltage levels (low, medium and high) and is used to detect:

– Corona
– Partial discharge or tracking
– Arcing
– Mechanical vibrations (transformers)

When electrical systems such as switchgear, transformers, insulators or disconnects and splices fail, the results can be catastrophic. This is just as true in industrial plants as it is in the power transmission and distribution side. If left undetected, these conditions can become a source of an arc flash incident, which can result in a major safety hazard & production fall out.

How ultrasonic electrical inspection works:

Partial discharge/tracking, arcing and corona all produce ionization which disturbs the surrounding air molecules. An Ultraprobe detects high frequency sounds produced by these emissions and translates them (via heterodyning) down into the audible ranges. The specific sound quality of each type of emission is heard in headphones while the intensity of the signal is observed on a display panel. These sounds can be recorded and analyzed through ultrasound spectrum analysis software for diagnosis & reporting.

Normally, electrical equipment should be silent, although some equipment such as transformers may produce a constant 50 cycle hum, or some steady mechanical noises. These should not be confused with the erratic, sizzling frying, uneven and popping sound of an electrical discharge.

Before beginning any inspection of electric equipment, be sure to review your plant or company’s safety procedures. We scan the equipment with the Ultraprobe and because of the characteristics of Ultrasound we can pinpoint the location of discharge quite fast & easy.

When it is not possible to get close to the test equipment, such as for safety reasons or while inspecting over-head power lines, use a parabolic microphone. UE Systems has two models, a parabolic dish – the Ultrasonic Waveform Concentrator (UWC) and the Long Range Module (LRM). These highly sensitive, directional sensors double the detection distance of a standard scanning module and provide pinpoint accuracy.

For more accurate diagnosis, ultrasound spectral analysis software helps identify sound patterns related to electrical emissions through spectral (FFT) and Time Series screens. Some of the more advanced instruments have on-board sound recording while others have on-board spectral analysis screens to help provide a diagnosis on the spot.