On-line testing of on-load tap changers with a portable acoustic system

Vibro-acoustic diagnostic of on-load tap changers (OLTC) offer numerous advantages: applicable online, sensitive to mechanical as well as electrical malfunctions, retrofitable to old equipment, simple and low-cost. Over the last few years, Hydro-Quebec has spent considerable efforts in the development of a reliable acoustic methods for both monitoring and diagnostics, this paper describes the methodology proposed for periodic testing via a portable acoustic system. First, the process to extract the OLTC signatures from acoustic recordings is briefly discussed. Then, the measurement approach is described along with the diagnostic procedure. Finally, actual field cases of diagnostic are presented to demonstrate the capabilities and the sensitivity of the acoustic method.