A Collective Condition Monitoring Algorithm for On-Load Tap-Changers

Transformer units are widely utilized to transfer the electric power over transmission and distribution networks efficiently. These units can be equipped with an on-load tap- changer (OLTC) to regulate the voltage level of power grids by tap changing operations between different steps of transformer winding to compensate unpredicted fluctuations of voltage. An OLTC is the solely moving and switching component of power transformers, thus it is highly prone to electrical, mechanical, and dielectric defects. Some international surveys indicate that the majority of the failures and outages with respect to power transformers are originated from malfunctions of OLTCs. This paper contains an analytical review of the existing methods for condition monitoring (CM) of OLTCs and proposes a collective CM algorithm, which considers the mechanical, electrical, and dielectric defects and degradations of OLTCs. The algorithm is designed to provide a comprehensive CM output for OLTCs by collecting different types of measurements from certain sensors used by different CM methods.