Motor-driven on-load tap changer within power transformers is extensively applied in the voltage regulation of power systems

in which principal malfunctions or failures are of mechanical type.Hence

the monitoring of mechanical characteristics of OLTC is of utmost significance for a safe

stable and reliable operation in power systems.Based on a rotating angular transducer as well as digital signal processing techniques

an on-line monitoring methodology is established to measure

analyse and evaluate the dynamic or transient changes in the rotating angle of the drive motor operational in an OLTC

which can effectively indicate the underlying deficiency or even potential fault of the mechanical drive system connected to the motor.An application system is developed together with practical installation method incorporated.Computer simulations and experiments are carried out respectively

both show that the proposed on-line monitoring scheme is feasible and applicable.