LIVE HV frequently provides On-Line Partial Discharge testing at Windfarms to diagnose and locate cable faults prior to failure.
In this case an Australian windfarm with over 50 turbines had recently been commissioned. LIVE HV was requested to verify the integrity of the newly energised 33 kV Cable network. In particular the client was interested in the quality of the associated cable Joints and Terminations.
To measure Partial Discharge in cables LIVE HV uses the Longshot testing unit and High Frequency Current Transformers (HFCT’s). The HFCT’s will detect discharge along the entire length of a cable while it remains energised. Advanced filtering hardware and software is critical to remove unwanted noise and get an accurate signal.
The testing for this site showed several separate discharge sites
The Next Step…
Because Partial Discharge had been detected on the cables the client was keen to find out where the offending sites were to allow for repair.
For this LIVE HV uses On-Line Cable Mapping. This technique can pinpoint the location of cable discharges while the cable remains energised.
An example of two of the cable mapping graphs is shown above. All of the discharge locations were found to be either at a Cable Joint or a Ring Main Termination.
PD Testing provided an assessment of the cable condition and pinpointed the location of all insulation concerns. The asset owner was then able to request repair from the contractor.