The selection of a partial discharge detector should be based on standard requirements and on-site interference characteristics. The pulse current method specified in IEC 60270 is the benchmark method for quantitative detection, with sensitivity up to 0.02 pC, and is suitable for laboratory and offline calibration scenarios. For equipment in operation, the ultra-high frequency (UHF) method covers the 300 MHz–3 GHz band, has strong anti-interference capability, and can penetrate metal enclosures, making it the preferred detection means for GIS combined apparatus; the acoustic emission (AE) method responds to mechanical vibration sound waves of 20 kHz–300 kHz, is immune to electromagnetic field interference, and is suitable for precise localization of discharge sources; the transient earth voltage (TEV) method captures transient earth voltages of 3 MHz–100 MHz in a non-intrusive manner, facilitating rapid screening of switchgear; and the high-frequency current transformer (HFCT) method targets pulse currents of 100 kHz–100 MHz on grounding lines, suitable for online monitoring of cables and accessories. During design selection, it should be confirmed according to the type of equipment under test and the interference environment whether the instrument supports the combined configuration of the above methods.
A single detection method is often limited by on-site conditions, and multi-sensor fusion has become an effective path to improve defect detection rates. The PD-3700 partial discharge detector supports the connection of four types of sensors—UHF, AE, TEV, and HFCT—and raises the defect detection rate to over 95% through cross-verification of data. During selection, attention should be paid to the synchronous sampling capability of each channel and the data fusion logic: the UHF channel is used for rapid capture of internal discharges in GIS, the AE channel is responsible for localization and pattern recognition, and the TEV and HFCT channels cover online monitoring of switchgear and cables, respectively. For substations dominated by GIS, the UHF+AE combination can be prioritized; for scenarios with dense switchgear, emphasis should be placed on TEV+AE; and for cable lines, the HFCT+AE scheme is preferable. The instrument should have plug-and-play sensor identification capability to reduce on-site configuration workload.
Design and selection personnel need to verify the instrument's measurement range, sensitivity, and real-time monitoring capability. The PD-3700 has a pulse current method measurement range of 0.1 pC–10000 pC, a UHF band of 300 MHz–1.5 GHz, an AE band of 20 kHz–300 kHz, a TEV band of 3 MHz–100 MHz, and an HFCT band of 100 kHz–100 MHz. The instrument features real-time monitoring, capable of synchronously displaying and controlling various set parameters, including the voltage of the entire battery pack, individual battery voltage, current, capacity, duration, and internal temperature, facilitating the grasp of equipment status during long-term live detection. In addition, the acoustic imaging function can superimpose the sound source acquired by the ultrasonic array onto the optical image to achieve visual localization and reduce dependence on operator experience. During selection, it should be confirmed whether the instrument provides an interface for the pulse current method per the IEC 60270 standard, so as to compare with laboratory calibration results.
The PD-3700 partial discharge detector is suitable for live detection and online monitoring of GIS combined apparatus, switchgear, power cables, transformers, and other equipment. In data center power supply systems, it can be used together with rack-mounted load banks for on-load stability testing to verify the coordinated operating status between the power supply system and the data service system. During selection, it is recommended to prioritize models with multi-physics coupling detection capability and to confirm the sensor configuration list according to the type of equipment under test. For sites requiring long-term monitoring, attention should be paid to the instrument's data storage capacity and communication interfaces; for mobile inspection scenarios, the overall weight and battery endurance need to be evaluated. Finally, it is recommended to require suppliers to provide third-party test reports to verify whether the sensitivity indicators of each detection method meet on-site requirements.
