Online partial discharge monitoring system for transformer

Online Partial Discharge Monitoring System for Transformer

What is partial discharge in transformer?

Partial discharge in a transformer, also called transformer partial discharge, is a phenomenon where repeated localized breakdowns occur in the insulation due to defects (like air gaps, impurities, or cracks) or excessive electric fields. While it typically doesn’t cause complete insulation breakdown, it can damage the insulation and lead to various hazards. Partial discharges in power transformers are classified into five types: internal, surface, corona, electric tree, and barrier PD discharge. To know more about partial discharge, read our blog post on what is partial discharge.

What causes partial discharge in a transformer?

Due to different transformer partial discharge types, there are different factors leading to transformer partial discharge.

During the manufacturing process or aging of a transformer, cavities may form within the insulation, creating higher voltage stresses that can lead to transformer partial discharge.

The dielectric strength at the insulation interface of the cable terminal, bushing, and line insulator is often lower than that of the bulk insulation, increasing the likelihood of transformer partial discharge.

In transformers, sharp conductive points, bare conductors, and even ground potential points in air or oil can initiate transformer partial discharge.

Within the transformer’s dielectric material, high electric fields can cause transformer partial discharge due to pollution, gaseous voids, or other defects.

The presence of an insulator (like silicon dioxide, quartz glass, or ceramics) between electrode pairs can also contribute to partial discharge in transformer.

What are the most critical locations for PD monitoring in a transformer?

To prevent transformer failures, a partial discharge monitoring system for transformers is necessary. Various types of transformers need to partial discharge monitoring system, including reactors, vault transformers, distribution transformers, dry transformers, and power transformers. What specific parts of a transformer require PD monitoring? In the transformer, the transformer tank, transformer winding, transformer ground wire, transformer drain valve, transformer plate, transformer bushings, and transformer OLTC need to monitor partial discharge.

Implementation An Online partial discharge monitoring system for transformers

Partial discharges in transformers can damage their insulation and may lead to transformer failure. Therefore, using a partial discharge monitoring system, you can detect partial discharges at an early stage and take corrective measures. Nowadays, there are many types of online partial discharge monitoring system for transformer, including partial discharge testing device, portable partial discharge monitor, Box type partial discharge monitor, integrated type partial discharge monitor, and general partial discharge monitor.

As for the online partial discharge monitoring system for transformer, the most common partial discharge monitoring tools are the following:

Rogowski coils are commonly used as sensors in partial discharge (PD) detection systems for transformers. They effectively monitor the high-frequency current pulses generated by PD activity, particularly those within the transformer’s insulation. Some people also employ a combination of a BAU (Bushing Adapter Unit) and Rogowski coil sensor, along with a coupling capacitor sensor, for enhanced PD monitoring.

PD3000 online partial discharge monitoring system for transformer is integrated with TEV,UHF,and AE(Ultrasoic/Acuostic) PD monitoring techniques, which is suitable to continuously assess the performance of insulation in different transformers. In traditional PD monitoring solution, you need to use UHF PD sensor to monitor partial discharge in the transformer tank, transformer winding, etc. As for PD monitoring in transformer ground wire, HFCT PD sensor are used. Now, no matter which condition, only one PD3000 can monitor PD in transformer accurately.

PD3000 PD Monitoring for Transformer

Suitable for various transformers

Combined TEV, UHF, and AE PD monitoring techniques

High accuracy and reliable safety for PD monitoring