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Partial Discharge Monitoring on Transformers

Partial discharge testing is required in order to be able to assess the quality of the power transformers. In an electric system, the failure of the insulation may ultimately lead to a complete breakdown. It has been found out that high percentage of failures is related to insulation problems concerning the power
transformers. PD monitoring helps detecting insulation, bushing, and winding problems. Failures can be due to improper factory acceptance test (FAT), transportation as well as onsite commissioning. Random failures are caused by particular stress such as high load, lightning or switching impulses.

The most common causes of PD in transformers are:

  • Sharp points and particles
  • Surface and tracking discharge
  • Fiber bridges in oil
  • Gas inclusions
  • Humidity (indirect)

Online PD monitoring is important to assess the insulation condition of power transformers as well as transformer accessories. PD trending and changing PD patterns help to  indicate an incipient failure. Further analysis of the phase resolved PD pattern assists with failure investigation in order to find out the root cause. In addition, PD monitoring can be extended to DGA, voltage, tan delta, temperature and load monitoring.

Brochure for  Transformer PD Monitoring Download

Bushing accessories 

Bushing coupling units are for permanent installation on power transformers. Together with a matching bushing adapter they serve to make different signals available for measurement and monitoring. The bandwidth of the partial discharge signals extends to 20 MHz. Due to the many different versions of transformer bushings and, hence, bushing test tabs, individual adaptation and flexible installation of bushing accessories are required for testing. Adiradh Energy offers various bushing adapters fitting to many different models of bushing test tabs.

UHF Transformer Sensors

UHF transformer sensors can be used to detect internal PD on power transformers in a frequency range between 300 MHz and 1 GHz. Adiradh Energy provides the TFS1 for valve flanges and the TVS2 for oil valves. Both sensors can be modified and designed in accordance of special customer specifications.

Complete PD monitoring system package  for power transformers:

1 x ICMmonitor (incl. SPEC & gating function)
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,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