Partial Discharge Tester (abbreviated as "PD Tester" or "PD Tester") is the "stethoscope" for insulation diagnosis of high-voltage electrical equipment. It can detect tiny, non-penetrating discharge phenomena (partial discharge) inside equipment, which are early signs of insulation deterioration. If not addressed promptly, partial discharge will gradually corrode insulating materials, ultimately leading to equipment breakdown and major power outages. Combining the latest technology trends of 2025-2026, here is an in-depth analysis of partial discharge testers: 1. Core Working Principles When partial discharge occurs, it is accompanied by various physical phenomena. The tester captures these signals through sensors for analysis: Electrical pulse signal (IEC 60270 standard method): Principle: Discharge generates transient pulse current, picked up via coupling capacitors or high-frequency current transformers (HFCT). Features: The only method that allows quantitative calibration (unit: picocoulomb pC), with high sensitivity, serving as the arbitration basis for factory tests and type tests. Ultra-high frequency signal (UHF method): Principle: Discharge radiates electromagnetic waves from 300MHz to 3GHz. Features: Extremely strong anti-interference capability, suitable for GIS (gas-insulated switchgear) and transformer internal detection, often used for online monitoring. Ultrasonic signal (AE method): Principle: Discharge produces mechanical vibrations, emitting ultrasonic waves from 20kHz to 200kHz. Features: Suitable for locating fault points (acoustic-imaging fusion technology), enabling non-contact detection on switchgear surfaces. Transient earth voltage (TEV method): Principle: Discharge electromagnetic waves induce transient voltages on the metal enclosure surface. Features: Mainly used for non-invasive inspection of switchgear without power outage. 2. Technology Trends for 2025-2026 According to the latest industry reports, current PD testers are undergoing a leap from "single detection" to "intelligent fusion": Multimodal fusion detection: Mainstream high-end instruments (such as new products from brands like Wuhan UHV, Guoke Dianyan, etc.) have integrated multiple sensors including UHF + TEV + ultrasonic + HFCT in one unit. Advantages: Simultaneously collects multiple physical quantities, cross-validates through algorithms, significantly reducing false alarm rates. For example, use TEV to detect anomalies, then use ultrasonic for precise location. AI intelligent diagnosis and pattern recognition: Built-in artificial intelligence algorithms automatically identify discharge types (e.g., corona discharge, floating discharge, surface discharge, internal void discharge). Automatically generates PRPD patterns (phase-resolved partial discharge patterns), compares with standard databases, and directly provides "health scores" and maintenance recommendations, reducing reliance on expert experience. Acoustic imaging fusion location: Handheld devices are equipped with microphone arrays and high-definition cameras. Effect: Directly overlays the discharge source location as a heatmap on the screen video, achieving "what you see is what you get" precise positioning, greatly improving inspection efficiency. Wireless connectivity and cloud management: Supports WiFi/5G transmission, with real-time data upload to cloud operation platforms. Enables full lifecycle insulation status trend analysis of equipment, promoting the shift from "periodic maintenance" to "predictive maintenance". 3. Main Application Scenarios Table Application Object Recommended Detection Method Typical Scenario High-voltage switchgear TEV + Ultrasonic Daily inspection of distribution stations, no power outage needed, rapid screening of insulation defects. GIS (Gas-insulated switchgear) UHF (internal/external) Factory factory tests, on-site commissioning tests, online monitoring during operation. Power transformers Pulse current method + UHF + Ultrasonic Factory routine tests, post-overhaul acceptance on site, fault diagnosis. High-voltage cables HFCT (High-frequency current transformer) Live detection of cable terminations and intermediate joints. Instrument transformers/bushings Pulse current method Laboratory precision measurement or on-site outage testing.
