Worldwide standardization process of sweep frequency response analysis (SFRA) and case studies

SFRA (Sweep Frequency Response Analysis) is a recognized method of detecting winding displacement in power transformers. In the case of SFRA, the focus is on investigating the mechanical and electrical integrity of the active component.

This paper describes the efforts to standardize the modern diagnostic procedures of SFRA and making the transition from the developmental stage to an documented procedure stage in SFRA. In the case of SFRA, the focus is on investigating the mechanical and electrical integrity of the active component. In 2002, the IEEE set up a task force for FRA, with a working group following in 2004, aiming to create FRA user guidelines. The IEEE Guide for SFRA is likely to be published in 2009. In 2003, the CIGRÈ Study Committee A2 on Transformers decided to set up a working group for SFRA applications involving power transformers. This WG A2.26, entitled “Mechanical Condition Assessment of Transformer Windings using Frequency Response Analysis (FRA)”, finished its work in 2008. Based on their findings an IEC WG was set up in early 2009. Already in 2005, in China the first binding standard relating to FRA, called DL911/2004, came into force and comparative study of all these standards will be discussed in detail.

Also, in this paper, Guidance on recommended practices is provided along with practical limitation of SFRA measurements and how winding movement can be identified from measured responses.