Pillar 4 of 8 · SDT Ultrasound Solutions methodology
Ultrasonic Detection of Corona Discharge and Electrical Arcing
📸 Photo: an inspector in PPE using an ultrasonic detector with a parabolic reflector to inspect insulators on an open switchyard or substation transformer
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Ultrasonic electrical fault detection is aimed at identifying corona discharge, electrical arcing, and insulation defects on high-voltage equipment. According to insurance and utility industry statistics, up to 80% of electrical failures can be predicted and prevented with regular monitoring. Ultrasound is the only method that allows inspection without de-energizing equipment and without approaching live parts.
Corona discharge, arcing, and insulation defects generate ultrasonic waves in the 20–100 kHz range, picked up by airborne sensors. A parabolic reflector enables detecting discharges from up to 10 meters away — on switchyard insulators, overhead line couplings, and transformer bushings.
KEG TRK supplies SDT Ultrasound Solutions detectors for electrical diagnostics across Almaty, Astana, Atyrau, Aktobe, and the whole of Kazakhstan. Training in the ultrasonic electrical diagnostics methodology is included with every delivery.
Types of Electrical Faults Detected by Ultrasound
One instrument — full control of a plant's electrical equipment.
Corona Discharge on Insulators and Cables
Corona discharge occurs on insulation surfaces under local overvoltage. It gradually degrades insulation and can lead to breakdown. Ultrasound detects corona from 5–10 m away from the sensor — with no contact with the equipment.
Electrical Arcing and Tracking
Arc discharges between conductors generate a strong ultrasonic signal. The detector instantly responds to arcing defects in switchgear, transformers, and cable connections.
Connection Point Defects
Loose bolted connections and oxidized contacts create localized heating and a characteristic ultrasonic signal long before visible signs of a defect appear. Detection without opening cabinets.
Substation and Overhead Line Insulators
Contaminated and damaged insulators on open switchyards and overhead lines create surface discharges. Ultrasonic scanning from a safe distance without approaching live parts.
How to Perform Ultrasonic Electrical Fault Diagnostics
Three steps from scanning to trend monitoring.
Point the Sensor at the Equipment
Use an airborne sensor with a parabolic reflector (for substations, switchyards) or a flexible waveguide (for cabinets). Scan from a safe distance — no need to open cabinets.
Listen To and Measure the Signal
Corona discharge creates a characteristic "hissing" sound when heterodyned, while arcing produces "crackling." The instrument displays the level in dBµV for objective assessment and comparison.
Log the Data and Track the Trend
Save the measurement, audio recording, and point coordinates. With regular measurements, the instrument builds trends — a rising signal indicates defect progression and replacement timing.
Benefits of Ultrasonic Electrical Fault Diagnostics
Safety, early detection, and documentation for power utilities and plants across Kazakhstan.
Safe Inspection Under Voltage
Ultrasonic diagnostics are performed remotely — without contact with live parts. There is no need to de-energize equipment to carry out the inspection.
Early Detection Months Before Failure
Corona discharge develops gradually. Ultrasonic monitoring identifies emerging defects months before insulation breakdown and an emergency shutdown.
Diagnostics in Noisy Environments
The 20–100 kHz range does not overlap with industrial noise. Corona and arcing are detected amid the noise of running transformers, motors, and ventilation equipment.
Reduced Fire and Explosion Risk
Electrical arcing and insulation defects are a leading cause of electrical fires. Timely detection prevents catastrophic consequences.
Documentation and Trending
Modern detectors record the signal and allow tracking defect progression over time. A rising amplitude is a signal for unscheduled maintenance.
Revealing Invisible Defects
A thermal camera only shows overheating. Ultrasound detects active discharges at their earliest stage — before the temperature has risen to the thermal camera's threshold.
Want to Detect Hidden Electrical Equipment Defects?
KEG TRK specialists will select the optimal kit for your voltage class and equipment type.
Get a ConsultationInstruments for Electrical Fault Diagnostics
From the entry-level ULTRAChecker to the professional SDT340 with parabolic reflector.
SDT340
ProfessionalA multi-sensor platform with Bluetooth HD, an airborne sensor, and a parabolic reflector for remote diagnostics.
Suited for: Critical high-voltage equipment
SDT270
Data and TrendsAn advanced detector with FFT spectrum, data logging, and trend analysis for monitoring defect progression.
Suited for: Electrical equipment monitoring program
ULTRAChecker
Easy StartA specialized detector for basic electrical fault diagnostics with no training required.
Suited for: First step, basic inspection
SDT200
For BeginnersA basic detector with an immediate audible indicator to start an electrical diagnostics program.
Suited for: Onboarding a monitoring program
Explore the Other Pillars of Ultrasonic Testing
The SDT methodology covers 8 areas — one instrument solves every task.
Frequently Asked Questions About Ultrasonic Electrical Fault Diagnostics
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