MOEORW-5085B Online Partial Discharge Monitoring Device for Transformers Send email to us

         Partial discharge in power transformers primarily occurs in the internal insulation of high-voltage electrical equipment under high-voltage conditions. This type of discharge is confined to localized areas of the insulation and does not immediately result in a complete insulation breakdown or flashover; hence, it is called partial discharge. Partial discharge is extremely weak and cannot be detected by human senses, such as sight or hearing; it can only be detected using highly sensitive partial discharge measuring instruments. 　　

       During operation, a transformer’s internal insulation is continuously subjected to the operating voltage. Particularly as the voltage rating increases, the electric field strength within the insulation becomes very high, making it highly susceptible to partial discharge in areas of weakened insulation. The causes of partial discharge include: an electric field that is overly concentrated at a single point, or an excessively high electric field strength at a specific point—such as when solid media contain bubbles or impurities that have not been removed; when oil contains water, gas, or suspended particles; or when severe electric field distortions exist at the interfaces between different media. Traces of partial discharge typically appear as a small spot or tree-like burn marks on solid insulation. In oil, small decomposition bubbles may form. Although partial discharges are brief and low in energy, they pose significant risks. Their prolonged occurrence can cause substantial damage to insulation materials. First, the insulation material adjacent to the partial discharge is directly bombarded by discharge particles. Second, the chemical effects of heat, ozone, nitrogen oxides, and other reactive gases generated by the discharge cause localized insulation corrosion and aging, increasing electrical conductivity and ultimately leading to thermal breakdown. In operating transformers, the aging and damage of internal insulation mostly begin with partial discharge. Therefore, partial discharge detection is a critical component of the daily operation and maintenance of power transformers.

Transformer high-frequency pulse current partial discharge detection technology holds a very important position among numerous detection methods due to its superior resistance to interference. High-frequency partial discharge detection offers strong resistance to electromagnetic interference. By filtering out noise through hardware circuits and extracting characteristic discharge signals, it presents partial discharge signals to maintenance personnel, enabling them to determine the intensity and location of partial discharges. This not only provides effective data for diagnosing equipment defects but also reduces maintenance time.

       This detection instrument employs multiple pulse current partial discharge sensors installed at the transformer’s grounded core. Through multiple acquisition channels, it performs lateral and longitudinal comparative testing, waveform display, characteristic analysis, and spectral extraction to conduct a multidimensional analysis of partial discharges during the operation of power transformers. This enables a comprehensive assessment of insulation issues and provides guidance for subsequent operation and maintenance.

       The transformer partial discharge online monitoring system primarily consists of front-end external pulse current sensors (FIPD-1000), a partial discharge acquisition unit, a computer server, and a partial discharge online monitoring software platform. The front-end sensors detect analog partial discharge signals from different locations and transmit them via coaxial cable to the partial discharge monitoring unit. The monitoring unit features signal filtering, amplification, and analog-to-digital conversion capabilities. It filters and amplifies the sensor-coupled signals to reduce noise and bring them within the AD conversion range. The partial discharge acquisition unit operates at a sampling rate of 100 MS/s with 14-bit resolution, simultaneously acquiring high-frequency discharge pulse signals from four channels via the synchronous control unit to maintain phase alignment with the power supply. It also employs a triggered acquisition mode: when the trigger signal reaches the trigger threshold, the partial discharge acquisition unit immediately acquires partial discharge signals for a specified duration. Since the system uses the same trigger signal to trigger all partial discharge acquisition units simultaneously, each acquisition unit achieves a high degree of synchronization, with a synchronization time difference of less than 100 ns.

      The system connects the various partial discharge monitoring units via fiber optics. The online monitoring platform software can adjust the data acquisition interval and data transmission interval of the acquisition units, while simultaneously receiving partial discharge waveforms returned by each acquisition unit, displaying and storing them in real time. Based on the discharge magnitude, polarity, and time difference of the partial discharges measured by each acquisition unit, and based on the statistical characteristics of the partial discharge waveforms, the system compares them with corresponding parameters in the expert database to identify partial discharge faults and further assess the severity of the partial discharge.