PD measurement technique for after-laying test of large-scale 110–500kV cable circuit

It is discussed firstly the correct way to install PD sensor HFCT to pick up PD current from cable joint based on a equivalent high frequency circuit of cable joint with a PD in it. PD measurement system for cable circuit under withstand high voltage test is different from that for regular PD periodical inspection on cable without outage to some extent. Especially for those long length circuit with many joints, it is required that the power supply system should be PD free and anti-corona, and the local signal processing unit distributed on each joint bay should obtain variable voltage frequency different from the 50/60Hz operating frequency, for PD recognition and judgment based on phase resolved partial discharge analysis. For PD detection and location it is also required that each signal processing unit should be in synchronization. It is shown that with on-site examples of the cable circuit of more than twenty joint bays passed through withstand test, how the PD sensor like HFCT was installed in the link box for cable sheath cross-bonding or grounding connection, how the test voltage was raised up step by step to cooperate with PD detection, and how to determine the configuration and specification of the multi-sites distributed PD measuring system.