Buyers evaluating partial discharge detectors ask a consistent set of questions. This FAQ answers them in plain language – from what PD actually is, to which technique fits which asset, to how live testing works without shutting equipment down.
What is partial discharge and why does it matter?
Partial discharge (PD) is a localised electrical breakdown of insulation that does not completely bridge the electrodes. It is a leading indicator of insulation degradation in high-voltage equipment – finding it early lets you repair before failure.
What are the main PD detection methods?
The four main methods: UHF sensors (electromagnetic pulses, ideal for GIS), TEV sensors (transient earth voltages, for switchgear and panels), ultrasonic sensors (acoustic waves, for surface discharge and internal PD), and HFCT clamps (high-frequency current pulses, for cables and transformer grounding). Many instruments combine two or more techniques.
How do I choose the right PD sensor?
Match the sensor to the asset and discharge mode: UHF for GIS; TEV combined with ultrasonic for switchgear and RMU; HFCT for power cables; and acoustic or combined methods for transformers. A sensor selection guide with the full comparison is available on this site (see the sensor selection article).
Can PD testing be done on live equipment?
Yes. TEV, ultrasonic and HFCT measurements are non-invasive and performed on energised equipment – the standard practice for switchgear surveys and transformer checks. UHF sensors on GIS can be fitted or applied live in many designs. Always follow the equipment owner’s live-working procedures.
What is the difference between a handheld detector and an online monitoring system?
A handheld detector is carried to assets and measures periodically – the right tool for surveys and patrols. An online monitoring system watches continuously, detects fast-developing defects between patrols and feeds alarms to the control room. Many utilities use both: handheld for coverage, online for critical assets.
Do you support OEM and ODM?
Yes. HUWOR is a manufacturer with in-house R&D, offering OEM and ODM for PD detectors, sensors and monitoring products, with R&D centres in Zhuhai and Xi’an. Buyers can private-label instruments and customise configurations.
How much does a PD detector cost?
Cost depends on technique coverage, channels and configuration – from handheld multi-function detectors to multi-channel online systems. A price guide with budget ranges is published on this site (see the price guide article).
What should I check when choosing a supplier?
Check manufacturing substance (own R&D and patents), technique coverage, documentation quality, training and application support, and total cost including calibration and spares. An eight-point supplier checklist is published on this site.
Is the company involved in standards?
Yes. HUWOR co-drafted three power-industry standards, including Q/GDW 12082-2021 (State Grid wireless sensor standard), the power industry standard for high-voltage ceramic capacitance sensors up to 35 kV, and T/EPTC 002-2022 for intelligent distribution transformers.
About HUWOR
Zhuhai Huawang Technology Co., Ltd. (HUWOR) manufactures handheld PD detectors, PD sensors, online monitoring systems, SF6 leak detectors and cable test sets for utilities and industry worldwide. Contact the HUWOR sales team with your specific questions – asset types, application and budget – for a direct answer.