PD Applications - Power, Distribution and Instrument Transformers

Online Monitoring

Partial discharge (PD) monitoring has become increasingly important in the past few years as PD trending information completes a full set of monitoring data for a transformer in the field, alongside other parameters like gas in oil analysis, temperature, vibrations, and load conditions.

To help with this, Megger offers a series of standard bushing adapters (BA) to connect the measurement system to the test tap of condenser bushings, and special designs are available on request. Additionally, the standard setup using the bushing test tap could be extended with UHF drain valve sensors or embedded antennas in flanges. For continuous monitoring, an instrument such as the ICMmonitor can be considered as its acoustic sensors can be used to locate a PD fault more precisely.

Aside from the preferred high frequency PD decoupling from the capacitive test taps of the transformer bushings (BA and BCU2C), you can optionally use the UHF signal as an alternative or in addition. Suitable UHF PD sensors are available from Megger for the oil drain valve (TVS2) or for flanges of inspection holes (TFS1). 

Using UHF sensors reduces external noise signals but has lower detection sensitivity for PD activity within the winding. High-frequency PD decoupling offers better sensitivity for internal failures but is more susceptible to noise. Combining both techniques provides a balanced approach.

Connection diagram for PD monitoring systems
Connection diagram for PD monitoring systems

 

 

 

 

Typical Packages:

Complete PD monitoring system for power transformers:

  • 1 x ICMmonitor (incl. SPEC & gating)
  • 1 x ICMmonitor software
  • 1 x Industrial monitoring cabinet (sheet metal or stainless steel)
  • 1 x Analog input card for parallel recording of misc. sensor signals like temperatures, vibrations, load conditions, etc.
  • 1 x Preamplifier RPA2B
  • 1 x Preamplifier RPA1H
  • 1 x High frequency current transformer CT1
  • 1 x Impulse calibrator CAL1B
  • 1 x Set of cables
  • 1 x Set of three bushing coupling units BCU2D
  • 1 x Set of bushing adapters BAxy (BA1–BA30)
  • 1 x Mounting kit for PD decoupling units