Partial Discharge Tester (referred to as PD tester) is a key device used to detect internal insulation defects in high-voltage electrical equipment
(such as transformers, GIS, cables, switchgear, etc.). It captures weak discharge signals generated by equipment under operating voltage, identifying insulation aging, cracks, or impurities in advance to prevent sudden failures.
Combining the latest technology trends and market products from 2025-2026, here is a detailed analysis of partial discharge testers:
1. Core Detection Principles and Methods
Modern PD testers typically adopt multi-sensor fusion technology to meet the needs of different equipment and scenarios:
Pulse Current Method (IEC 60270 standard):
Principle: Detects pulse current generated by discharge through coupling capacitors.
Application: Precise quantitative measurement (unit: pC) during laboratory factory tests and outage maintenance.
Features: High sensitivity (up to 0.01pC), authoritative data, but requires outage and wiring.
Ultra-High Frequency Method (UHF):
Principle: Receives electromagnetic wave signals in the 300MHz-3GHz frequency band.
Application: GIS (Gas Insulated Switchgear), transformer internal detection.
Features: Strong anti-interference capability, suitable for online monitoring, and can perform positioning.
Ultrasonic Method (AE/Ultrasonic):
Principle: Captures acoustic signals generated by discharge (20kHz-200kHz).
Application: Switchgear, overhead lines, transformer external positioning.
Features: Non-contact, can be tested live, convenient for rapid inspection and precise fault location.
Transient Earth Voltage Method (TEV):
Principle: Detects transient voltages induced on the metal enclosure of switchgear due to internal discharge.
Application: Live inspection of medium and high voltage switchgear.
Features: No need to open the cabinet door, extremely simple operation, and is the mainstream method for distribution network maintenance.
2. Mainstream Technical Parameters and Functions in 2025-2026
According to the latest market products (such as new models from Wuhan Moen, Guoke Dianyan, Yangzhou Haiwo, etc.), high-end PD testers have the following features:
Table
Function Module Typical Technical Indicators (2026 Model) Description
Detection Sensitivity 0.01 pC - 0.1 pC Meets high-precision quantitative analysis requirements.
Sampling Rate 20 MS/s - 100 MS/s High sampling rate ensures waveform details are not lost.
Detection Frequency Band Broadband coverage:
Current method: 10k-500kHz
UHF: 300M-1500MHz
Ultrasonic: 20k-100kHz
TEV: 3M-100MHz Multi-function in one unit, covering full frequency band interference filtering.
Display and Analysis 10-inch or larger high-definition touch screen
Supports PRPD/PRPS patterns Real-time display of ellipse, sine, and straight-line modes; built-in AI algorithm automatically identifies discharge types (such as floating discharge, tip discharge, surface discharge).
Positioning Function Acoustic-electric joint positioning / array positioning Some high-end handheld devices are equipped with microphone arrays, generating "acoustic images" to visually display discharge point locations.
Connectivity and Intelligence WiFi/Bluetooth/5G Supports wireless control via mobile phones/tablets, cloud data upload, and automatic generation of standardized reports.
Anti-interference Capability Digital filtering + threshold setting Can extract effective signals in strong electromagnetic interference environments (such as operating substations).
3. Representative Models and Application Scenarios (2026 Reference)
A. Portable/Inspection Type (Main Force for Live Detection)
Applicable Scenarios: Daily maintenance, switchgear inspection, rapid fault location.
Representative Models:
HVJF9004 / HPD500 (Yangzhou Haiwo): Integrated TEV and ultrasonic sensors, handheld design, suitable for rapid screening of switchgear.
HZJF-SC128 (Wuhan Hezhong): Two-in-one earth wave and ultrasonic, built-in trend analysis, suitable for distribution network maintenance.
Guoke Dianyan handheld series: Uses microphone array technology, supports acoustic-image fusion positioning, high visualization.
Features: Lightweight, no outage required, foolproof operation (training <4 hours).
B. Precision Quantitative Type (Factory/Preventive Tests)
Applicable Scenarios: Factory tests of transformers, instrument transformers, cables, or acceptance tests after major repairs.
Representative Models:
MEJFD-1S (Wuhan Moen): Complies with IEC 60270 standard, 10.1-inch touch screen, supports one-click calibration, extremely high accuracy.
TLHG-2025 (Wuhan Tianligao): Dual-channel design, sampling rate 20M/S, supports ellipse/sine display, suitable for scientific research and high-precision testing.
Features: Requires coupling capacitors and corona-free test transformers, data has legal validity.
C. Online Monitoring Systems (Long-term Monitoring)
Applicable Scenarios: 24-hour monitoring of critical equipment in important hub substations, offshore wind power booster stations, etc.
Representative Models:
MOEORW online series: Supports multi-channel synchronous acquisition, with remote alarm and expert diagnostic systems.
Features: Fixed installation, real-time data upload to control room or cloud platform.
4. Purchasing Recommendations
Clarify the purpose:
For daily inspections (especially switchgear), prioritize handheld TEV+ultrasonic integrated devices, focusing on portability and positioning functions.
For handover tests or scientific research, must choose pulse current method instruments that comply with IEC 60270 standard, focusing on sensitivity (pC level) and calibration functions.
For GIS equipment, prioritize dedicated instruments with UHF sensors.
Anti-interference capability: The field environment is complex; ensure the instrument has digital filtering, frequency selection, and background noise suppression functions.
Pattern analysis capability: Excellent instruments should have built-in PRPD (Phase Resolved Partial Discharge) pattern libraries, automatically assisting in discharge type identification, reducing dependence on operator experience.
Compliance: Ensure the instrument complies with the latest national standards (GB/T 7354) and power industry standards (DL/T 417, DL/T 846.4, etc.).
5. Market Price Reference
Basic handheld inspection instruments (TEV/ultrasonic): approximately 15,000 - 35,000 RMB.
Multi-functional precision PD testers (including host, coupling unit, calibrator): approximately 40,000 - 80,000 RMB.
High-end online monitoring systems (multi-channel, including software platform): starting from 100,000 RMB, depending on the number of channels and equipment scale.
If you need test solutions for specific equipment (such as "110kV transformer" or "10kV switchgear"), or need to know the specific operation video/manual of a certain instrument, please let me know!
