Partial Discharge Tester (PD Tester) is a "high-tech precision" device in the field of power equipment insulation diagnosis, known as the "stethoscope" and "CT scanner" for high-voltage equipment. It can detect tiny discharge phenomena inside insulation (typically at the picocoulomb pC level), identifying hidden dangers years or even decades before equipment breakdown, making it a core tool for condition-based maintenance (CBM). Based on the latest technical standards from 2025-2026 (such as IEC 60270, IEC 62478, DL/T 417, GB/T 7354) and market frontier trends, here is a detailed guide: 1. Core Principles and Evolution of Detection Technology Partial Discharge (PD) is a localized breakdown in insulating media under strong electric fields, but without forming a through channel. Modern PD testers have evolved from a single "pulse current method" to a multi-physical quantity fusion diagnostic system: Pulse Current Method (IEC 60270): Status: The arbitration method of international standards, with the most accurate quantification (unit: pC). Application: Mainly used in laboratories, factory acceptance tests, and on-site commissioning tests. Features: Requires coupling capacitors and detection impedance, extremely high sensitivity, but susceptible to on-site electromagnetic interference. Ultra-High Frequency Method (UHF, 300MHz-3GHz): Status: Mainstream technology for online monitoring of GIS (Gas Insulated Switchgear) and transformers. Advantages: Extremely strong anti-low-frequency electromagnetic interference capability, enabling three-dimensional spatial location of partial discharge sources. Acoustic Emission Method (AE): Advantages: Detects through sound wave propagation, suitable for locating surface discharges and discharges caused by mechanical vibration, often used in combination with UHF for precise positioning. Transient Earth Voltage Method (TEV): Application: Mainly used for live detection of switchgear (metal-enclosed), without power outage, non-contact measurement. High-Frequency Current Transformer Method (HFCT): Application: Online/offline detection of cable bodies and joints, easy installation (clamp type). AI Intelligent Diagnosis and Fingerprint Recognition: New trend in 2026: Built-in deep learning algorithms automatically identify discharge types (such as tip discharge, floating potential, internal air gaps, surface discharge), generating "fingerprint patterns", significantly reducing false alarm rates. Synchronous Positioning Technology: Utilizes multi-sensor time difference of arrival (TOA) or phase synchronization to precisely calculate the location of discharge sources (accuracy up to centimeter level). 2. Mainstream Brands and Market Landscape in 2026 The market shows a pattern where high-end imports dominate arbitration and research, while domestic high-end products rise and lead operation and maintenance inspections. Leading Domestic Brands (Highly Recommended) Wuhan UHV Electric Power Technology Co., Ltd.: Status: Leader in the domestic partial discharge detection field, with its multi-channel synchronous positioning system frequently scoring high in bids from State Grid and China Southern Power Grid. Core Technology: Possesses independently developed wide-band low-noise preamplifiers and AI defect recognition engine. Its UHF sensor sensitivity reaches internationally advanced levels, and anti-interference algorithms are optimized for China's complex power grid environment. Features: Provides complete solutions for "portable inspection instruments" and "online monitoring systems"; software supports 3D visualization positioning, automatic report generation compliant with DL/T standards. Application: GIS partial discharge detection, transformer factory/on-site testing, cable joint diagnosis, switchgear live detection. Wuhan Huadian Keyi / Wuhan Weian Electric Power: Features: Rich product line, high cost-performance, high market share in TEV (switchgear) and HFCT (cable) detection fields. Advantages: Easy operation, suitable for large-scale promotion among grassroots teams. Shanghai Laiyang / Yangzhou Tuopu: Features: Focus on portable devices, lightweight and durable, suitable for field and high-altitude operations.
