In medium to high voltage electrical systems, disturbances such as arc flash and partial discharge (PD) can cause serious damage if not detected early. Both are signs of insulation degradation or gaps between conductors that can trigger fires, explosions, or damage to electrical equipment. Unfortunately, these disturbances often occur in forms that are not directly visible and inaudible to the human ear.
However, with the help of Video Acoustic Imagers (VAI), early detection of these electrical disturbances has become easier, faster, and safer.
What Are Arc Flash and Partial Discharge?
Arc flash is a large electrical surge that occurs when current passes through an air gap between conductors, usually caused by damaged insulation, dust, moisture, or loose connections.
Partial Discharge (PD) is a small electrical discharge that occurs in or around electrical insulating materials. Although small, PD is gradually destructive and serves as an early signal of potential system damage.
How Does a Video Acoustic Imager Work?
A Video Acoustic Imager is a device that combines an ultrasonic sensor and a visual camera to detect and map high-frequency sound sources into images.
Detection Process:
- An ultrasonic microphone captures high-frequency sound (ultrasound) generated by a PD or arc flash.
- This sound is visualized as an acoustic hotspot on the camera screen.
- Operators can see the exact location of the fault even from a distance, without having to open the electrical panel or approach high-voltage equipment.
Why is a VAI Effective for Electrical Fault Detection?
- Sensitive to Ultrasound Frequencies
Partial discharges and arc flashes produce high-frequency sounds above 20 kHz. A Video Acoustic Imager can capture these sounds, even though they are inaudible to humans.
- Real-Time Visualization
Unlike conventional listening devices or thermal cameras, a VAI displays a live acoustic map in video. The sound source can be quickly identified and approached cautiously if necessary.
- Remote Security
Technicians can conduct inspections from outside the panel or room, avoiding direct exposure to electrical hazards. Suitable for facilities with high voltages and limited access.
- Early Detection & Predictive Maintenance
PD often appears months before major damage occurs. With VAI, early signs can be quickly recognized and acted upon, preventing downtime and major damage.
Field Applications
This technology is very useful in:
- Inspection of high-voltage substations and panels
- Monitoring of electric motors, transformers, switchgear, and busbars
- Inspection of cable and connector insulation
- Electrical audits in production and industrial facilities
Brief Case Study
A large manufacturing plant uses a Video Acoustic Imager to routinely inspect medium-voltage electrical panels.
A small spot of partial discharge was discovered inside one of the panel cubicles. Without VAI, the spot would have gone undetected because it showed no excessive heat or other physical signs. After manual inspection, cracks in the insulation were discovered due to moisture.
Arc flash and partial discharge are hidden threats in electrical systems that can have significant impacts if left unchecked. Video Acoustic Imager technology makes detecting these faults more accurate, faster, and safer.
This technology is not just an inspection tool, but a vital part of modern predictive maintenance and electrical risk management strategies.
