Past experience and future developments toward the safeguarding of power transformers

Transformer in a substation fails due to ageing and/or incipient faults. Many diagnostic methods have been developed based on chemical and electrical techniques. However, most of these methods require specialist knowledge for accurate interpretation of measurement data before reaching any diagnostic conclusions. This paper outlines the key issues involved in power transformer monitoring and diagnosis and presents two cases studies to demonstrate the importance of interpretation techniques for the accurate condition assessment of transformers. This paper briefly discusses the characteristics and requirements of an intelligent on-line monitoring, diagnosis and management system for safeguarding in-service transformers.