Sonic & Thermal Technology

Sonic and Thermal technologies are a perfect match when conducting inspections of electrical equipment.  At any voltage, thermal anomalies and sources of Sonic such as arcing can occur. Corona can also occur at 1000 volts and greater. Any of these conditions threaten the reliability of the equipment being inspected. When it comes to electrical inspection, Sonic instrumentation can be used on almost any energised electrical equipment  including metal-clad switchgear, transformers, substations, relays, and motor control centres just to name a few.  

Sonic test instruments can be used to inspect energised electrical components that are on low, medium, and high voltage systems. Typical electrical components that can be inspected with Sonic and Thermal  include: 

Switch gears, Load interrupter switches, Breakers, Transformers, Motor control centres, Terminal transition cabinets.  As a further complement to Thermal inspections and to aid in the proper diagnosis of the condition, recorded Sonic can be seen in Time Wave Form from spectrum-analysis software – this will show how to properly diagnose electrical anomalies. This form of analysis is referred to as Sonic imaging.

When it comes to electrical inspection, Sonic instrumentation can be used on almost any energised electrical equipment including metal-clad switchgear, transformers, substations, relays, and motor control centres just to name a few.  

Traditional inspection of energised electrical equipment has been performed by non-contact Thermal cameras. However, in recent years, Sonic Test instruments have been added to these inspections for various reasons. One of the main reasons  has been safety. A Sonic inspection of electrical equipment can be performed without opening the cabinet or enclosure. 

Sonic and Thermal Imaging Technologies: Examples 

2500-amp main breaker (Figure 1) 

Figure 1 represents a 2500-amp main breaker. Arcing was detected on the Brown Phase side. The arcing heard was worse when the load increased. The arcing has severely deteriorated the internal contacts, and eventually will become so deteriorated that the voltage and wave form will be unable to reach the load. The main switch was identified and made a priority for shutdown/service to avoid a major incident occurring.

The Time Waveform from the recorded Sonic test shows characteristic patterns of arcing. Changes in amplitude and a loss of well-defined 60Hz harmonics. 

2000 KVA 11KV-415v cast resin transformer 

This shows an example of a 2000 KVA 11KV-415v cast resin transformer. An inspection on this equipment was requested after audible noise in the area increased, so the operators knew something has changed for the area to become louder. The inspection was done during the winter months, and for this facility, this transformer typically sees a reduction in load as it supplies chillers and associated other plant equipment that normally does not work as hard during the winter months. During the inspection it was noted that the load was around 450 Amps per phase.

Time Waveform view of the Sonic test of this contractor shows distinct signs of severe tracking and early stages of arcing. A planned shutdown and a full service was completed to rectify this dangerous situation.

Contactor 

Example of a contactor on a piece of equipment called an orbit motor. A routine Sonic inspection was done, and distinct sounds of tracking were heard. A follow up inspection with Thermal imaging was performed, and the diagnosis was severe tracking. 

 Measures up to 650°C, offers 3 spot meters and displays the max/min temperature within an area live, on-screen 

• Spot-size ratio allows you to take the most accurate temperature readings on smaller targets, at farther distances

• Built-in voice annotation and customisable work folders makes finding and documenting problems easier and more efficient

• Report problems in electrical panels and buildings for insurance claims, preventative maintenance and routine