Comparison of the Four Core Partial Discharge Detection Technologies: In-Depth Analysis of Principles, Advantages, and Applications

In the field of safety maintenance for high-voltage electrical equipment, Partial Discharge Detection (PD Detection) plays a critical role as an early warning system. As global power grids demand higher reliability for key assets such as transformers and reactors, mastering accurate and efficient PD detection technologies has become an industry consensus. This guide provides a detailed analysis of the four mainstream international detection methods: the Pulse Current Method (IEC 60270 Standard), Ultrasonic Method (Acoustic Emission), Ultra-High Frequency (UHF) Method, and Transient Earth Voltage (TEV) Method, helping you develop a scientific equipment health management strategy.

Content

1. Pulse Current Method (IEC 60270 Standard Method) – The Gold Standard for Reference

●Core Principle: Electromagnetic Induction for Quantitative Capture
 The Pulse Current Method adheres to the IEC 60270                         international standard and is the benchmark for PD   quantification. This method detects transient current pulses  caused by partial discharges by connecting a precision detection impedance (Zm) in series with the equipment’s grounding wire or coupling capacitor (Ck). When a discharge occurs within the insulation, rapid charge migration generates a sudden current change (di/dt).●According to Faraday’s Law of Electromagnetic Induction:

V(t) = M × di/dt

Here, V(t) is the transient voltage across the detection impedance, and M is the mutual inductance coefficient of the measurement circuit.

Using a high-speed acquisition system to record the V(t) waveform, the Apparent Charge (Q) can be precisely calculated:

Q = ∫i(t)dt ≈ (1/R) × ∫V(t)dt

where R is the resistive component of the detection impedance

In-Depth Analysis of Advantages and Limitations

2. Ultrasonic Method (Acoustic Emission) – The Mechanical Wave Localization Expert

●Core Principle: Tracking Acoustic Wave Propagation Paths
Partial discharges generate micro-explosions, producing mechanical vibrations (20kHz-300kHz). Piezoelectric sensors placed on the equipment surface capture these signals. The system uses Time of Flight Difference (TOFD) for 3D localization:

∆t = (d1 - d2)/v

 Here, v is the wave speed in the medium (~1400m/s in oil, ~2400m/s in epoxy)

∆t is the arrival time difference between sensors.

In-Depth Analysis of Advantages and Limitations

3. Ultra-High Frequency (UHF) Method – The Electromagnetic Wave "X-ray"

●Core Principle: Capturing GHz-Band Electromagnetic Pulses

PD generates steep current pulses (rise time <1ns),                emitting 300MHz-3GHz electromagnetic waves. Built-in UHF sensors (e.g., Archimedean spiral antennas) inside equipment (e.g., transformer tanks, GIS chambers) detect these signals.

In-Depth Analysis of Advantages and Limitations

4. Transient Earth Voltage (TEV) Method – The Rapid External Diagnostic Solution

●Core Principle: Electromagnetic Coupling at Metal Interfaces
PD near grounded shields induces nanosecond transient voltages on metal surfaces. Capacitive probes detect these Transient Earth Voltages (typically <1V):

V_tev = k × (dQ/dt) × Z_c

      Here, k is the coupling coefficient

 Z_c is the surface wave impedance (80-150Ω).

In-Depth Analysis of Advantages and Limitations

Technology Decision Matrix: Key Factors for Application Matching

In Summary

Global best practices (e.g., CIGRE WG D1.37) show that single-method solutions struggle with complex scenarios. Leading systems now adopt multi-modal data fusion:

Pulse Current + UHF:Combines quantification and noise immunity (e.g., ABB Guardus).

Ultrasonic + TEV:Enables fast switchgear PD localization (e.g., Omron PD-TEV).

AI-Driven Diagnostics:Uses IEEE Std C57.104 and machine learning (e.g., PSO-SVM models).

PG&E (USA) reported that UHF-ultrasonic fusion extended transformer fault warnings by 37 days and cut costs by 52%.

With IEC 62478 (UHF) standardization and AI advancements in PD pattern recognition, the field is evolving toward higher precision and smarter diagnostics. Follow updates from IEEE Dielectrics and Electrical Insulation Society for cutting-edge trends.

Global grid stability begins with precise detection of microscopic discharges. When these four technologies form a diagnostic network, every captured pulse and analyzed sound wave rewrites the future of electrical reliability—leaving no room for unexpected failures.

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