Partial discharge diagnostics for mixed-technology switchgear (MTS) in outdoor substations

The application of the UHF method to PD measurements in MTS substations presents technical challenges due to the much higher external noise in outdoor substations. To adapt the UHF technique to handle these challenges, a series of tests was performed in the laboratory and at selected substations. Different PD sources were inserted in a test rig, and the proposed UHF detection system was evaluated. On-site measurements using this system showed that the spectra of external and internal PD sources differed considerably, suggesting that the system is capable of yielding reliable indications of the presence of PD in MTS.