Benefits of a vibro-acoustics-enhanced method for assessing the condition of high-voltage circuit breakers

Modern HVCBs are typically self-blast breakers filled with insulating and arc-quenching gas.

For condition assessment, they can be divided into three fault-prone areas: the control section, the operating mechanism, and the interruption chamber. This publication first identifies the root causes of failures in each area, which is fundamental for effective condition monitoring and assessment. Based on these causes, specific condition indicators are derived and evaluated for their relevance. For indicators with high diagnostic value, we examine whether established online or offline measurement methods exist. Where such methods are lacking or only available offline, the potential of vibroacoustic measurements is assessed.

This evaluation is not purely theoretical but supported by practical measurements on a gangoperated 110 kV SF6 self-blast HVCB with spring drive. Several sensors were positioned at different points on the breaker, and their signals were recorded using laboratory equipment. In addition, a monitoring prototype suitable for field application was developed and successfully tested. Furthermore, a method for labelling vibroacoustic signals was designed and applied.

Previous approaches to vibroacoustic analysis of HVCBs have focused solely on the mechanical domain and often only detect anomalies. In contrast, the method developed here provides deeper insights. Vibroacoustics enables the identification of distinct events during a switching operation, such as the start of plunger movement, the spring charging time, and the moment the main contact reaches the damper. The latter is particularly promising for approximating the switching time, which in standard practice is often only available through offline measurements.

Finally, the advantages and limitations of the proposed vibroacoustic diagnostics are discussed.

The results show that online vibroacoustic signals recorded during switching operations are fundamentally suitable for assessing the overall condition of HVCBs.