Partial discharge is an early sign of insulation degradation in high-voltage electrical equipment. If not detected in a timely manner, it may gradually develop into insulation breakdown and cause power outages. With the deepening promotion of the concept of condition based maintenance in the power industry, portable partial discharge testing equipment has become a standard tool for the operation and maintenance of substations, distribution rooms, and cable lines. However, facing various products in the market ranging from thousands to tens of thousands of yuan, how to scientifically select has become a practical problem faced by many operation and maintenance units.

Technology matching comes first, clarify the detection object

The first step in selection is not to look at the parameter table, but to clarify the detection object. The partial discharge signal characteristics of different high-voltage equipment vary significantly, and the required sensing technologies are also completely different. For metal enclosed equipment such as GIS and oil immersed transformers, ultra-high frequency (UHF) method is the preferred solution, with a detection frequency range covering 300MHz to 3GHz, which can effectively avoid conventional interference such as on-site corona discharge and has extremely high sensitivity. The combination of transient ground voltage method and ultrasonic method is more suitable for switchgear inspection. This dual technical solution combines rapid screening and preliminary positioning capabilities, and is recognized as the golden configuration for switchgear inspection in the industry. The detection of high-voltage cable terminals and intermediate joints relies on high-frequency current sensors (HFCT), which can achieve relative quantitative evaluation of discharge capacity by coupling discharge pulse current on the grounding wire through clamping.

Wuhan UHV follows this logic in equipment configuration when serving customers. The electrical testing team of a certain oil field in Henan needs to conduct partial discharge inspections of transformers, switchgear, cables, and GIS simultaneously. The company recommends the UHV-8003 partial discharge inspection instrument, which is equipped with multiple sensors such as ultrasonic and ultra-high frequency. One device can cover the detection needs of the above four types of equipment.

Core indicators: sensitivity, frequency band, and anti-interference ability

After determining the technical roadmap, the consideration of performance indicators is particularly crucial. The detection sensitivity directly determines the ability of the device to detect early weak defects, usually expressed in pC units, with lower values indicating higher sensitivity. For factory level precision testing scenarios, a sensitivity level of 0.1pC has become the basic threshold for high-end equipment.

The coverage range of the detection frequency band cannot be ignored. The testing bandwidth range of UHV-8003 is 30kHz to 2.0GHz, and this wideband design enables it to adapt to various detection principles ultrasound to ultra-high frequency, achieving multi technology fusion on a single platform.

The anti-interference ability is the most easily underestimated indicator. The electromagnetic environment at the substation site is complex, and equipment with excellent laboratory performance may frequently report false alarms on site. An excellent partial discharge detector should have the ability to filter signals and identify noise, and be able to extract real discharge information complex background signals. The partial discharge testing system of Wuhan ultra-high voltage adopts ultra-high frequency sensors and digital filtering technology, with a detection sensitivity of 0.1pC, providing users with high-precision detection data.

The ability of graph analysis determines the depth of diagnosis

If sensors determine whether they can measure, then the ability to analyze spectra determines whether they can understand. PRPD and PRPS maps are internationally recognized tools for identifying discharge types, which can effectively distinguish between tip discharge, suspended discharge, and internal air gap discharge in insulation. They are important indicators for distinguishing professional equipment entry-level equipment.

UHV-8003 supports the output of various discharge spectra such as time-domain waveform, PRPD, PRPS, etc. It can identify the frequency of discharge and determine the fault type through multiple mode analysis. For the operations team, this ability means a leap "discovering anomalies" to "determining the nature of anomalies".

Portability and battery life: practical constraints for on-site operations

The inspection work of partial discharge often requires continuous operation between multiple devices, and sometimes dozens of switchgear need to be inspected in a day. The weight and battery life of the equipment directly affect work efficiency. The UHV-8003 host weighs only 0.4kg and is equipped with a 10000mAh lithium battery. It has a battery life of about 12 hours and a working temperature range of -20 ℃ to 50 ℃, which can meet the needs of all-weather outdoor inspections.

Establish a three-dimensional evaluation system of "technology matching performance verification service guarantee"

Overall, the selection of portable partial discharge testing equipment should not be solely price driven. Before procurement, it is recommended that the operation and maintenance unit establish an evaluation system three dimensions: first, confirm whether the equipment covers its own detection object types to avoid problems such as functional redundancy or insufficient scene adaptation; Secondly, the focus is on verifying whether the sensitivity, frequency band range, and anti-interference ability meet the actual working conditions on site; Finally, the technical training support and after-sales service level of the manufacturer will be examined, as partial discharge testing not only involves equipment operation, but also tests data analysis experience. The technical support after equipment delivery often determines whether it can truly play its value.

The complete technical information and operation videos provided by Wuhan UHV in customer service, as well as the feedback and tracking of equipment usage after arrival, are the embodiment of this evaluation system in practice.

The core value of partial discharge detection lies in "early detection and early disposal". Choosing a portable testing device that is truly suitable for one's own operation and maintenance scenario is not only an investment in the safety of power assets, but also a guarantee for the efficiency of the operation and maintenance team.