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The PDExpert is PMDT's third level of Partial Discharge (PD) Expert Diagnostic and Location System. It is a powerful, portable, multi-channel system of impeccable design used to analyze and pinpoint PD signals coming from a power asset within centimeters while the power system is energized. The system consists of UHF, AE, HFCT and ultrasonic sensors, one advanced UHF/PD signal processing unit, one oscilloscope, filters and other accessories.

The system employs ultra-high speed data acquisition and advanced digital signal processing technologies, compares the UHF, AE and HFCT signals of different frequency ranges to determine if it is PD or noise, and locates the source in power assets accurately by utilizing Acoustic-Electromagnetic Combination Location Technique, time Difference of Signals' Arrivals (TDOA), and 3D Positioning Technology.


The PDExpert is an ideal trouble-shooting tool for your PD programs. Location of PD, which phase has PD, PD types, and severity are determined and maintenance suggestions are provided accordingly.  

System Configurations

The PDExpert consist of the following components:

•  3 UHF Sensors                

•  3 HFCT Sensors

•  2 AE Sensor w/Amplifiers

•  Oscilloscope

•  Advanced UHF/AE PD Signal Processing Unit

•  Filters

•  Signal Cables 

Main Features 

  • Employs a combination of UHF, AE, HFCT, and Ultrasonic sensors to comprehensively analyze the PD signal and provides the most reliable condition evaluation of the operational status for the power asset

  • Utilizes a high-speed digital oscilloscope to analyze the waveform details and the time domain characteristics of the UHF/AE/HFCT signals

  • Utilizes Acoustic-Electromagnetic signal detection and UHF 3D location techniques to analyze, diagnose, and locate the PD signals source within centimeters

  • Determines the PD types based on the signal's time-domain and frequency domain characteristics, even when the background noise is strong

  • Determines PD or noise using Time Difference of Signals' Arrival (TDOA) location method and locates the external noise source acurately

  • Utilizes multi-source location technology to prevent signals fro interfering with each other and locates the signal sources individually

  • Various combinations of sensors are used to locate the PD signal source accurately by using TDOA location method. For example: AE-AE, UHF-UHFm HFCT-HFCT, AE-HFCT, and AE-UHF sensors

Advanced UHF/AE PD
Signal Processing Unit

The Advanced UHF/AE PD Signal Processing Unit is designed to amplify and process the UHF and AE signals.


The high-speed digital oscilloscope with 4GS/s sampling rate and 1G bandwidth is ideal to collect the details of the UHF/AE/HFCT signal waveforms, analyze the initial edge and characteristics of the signal waveform and locate the PD signal source accurately. 

System Sensors

UHF Grey
HFCT Sensor Grey Blackground
AE Contact Sensor for PDExpert
Ultrasonic sensor for PDMonitor.png

PMDT's Typical Diagnostic Spectrums 

Multi-Period Spectrum

Determining the PD signal type.

PDExpert Multi-Period Spectrum
TDOA Location Spectrum

Determining the location of the PD signal source.

PDExpert TDOA Location Spectrum

PD Signal Sources Comparison Spectrum 

Acoustic-Electromagnetic Location Spectrum 

Determining the distance between the PD signal source and the AE sensor. 

PDExpert Acoustic-Electromagnetic Locati
Phase Determination Spectrum 

Determining which phase the PD signals are coming from.

PDExpert Phase Determination Spectrum


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PDExpert for GIS.png
PDExpert for Power Cables
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