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The Doble SFRA Resource CenterWelcome to the Doble SFRA Resource Center. FRA is the general term for Frequency Response Analysis; SFRA is specific to Sweep measurements which are more repeatable and reliable for decision making. A page of FAQ's is also available. Contents Introduction Introduction We hope this site provides useful information to allow you to:
SFRA Role, Value and Benefits SFRA is an electrical test which gives information about transformer mechanical integrity. When making decisions about transformers, there is a degree of caution as mistakes may be catastrophic and costly. SFRA helps with decision making, and by removing uncertainty, has a value in its own right. Problems it can pick up include: shorted turns, hoop buckling, axial collapse, clamping structure failure and related problems. Case studies are available for each situation. There is value in the identification of problems, but there is also great value in being able to say that there is unlikely to be a problem: where SFRA results show no change with a baseline, this is very strong evidence that there has been no significant winding movement and/or distortion within the transformer. This is without the requirement of an internal inspection which entails costly outages, maintenance personnel intrusion and oil handling, all of which may reveal nothing. Testimonials as to the value of SFRA have been collected. Summary: value/benefit is identifying where a problem exists; however, a null result is very useful in identifying an 'all systems go' situation, particularly after a fault. SFRA Basics - what is it and how is it done The Technical Paper gives a good introduction to SFRA overall; in addition we have two documents used for CSE training which look at the basics of SFRA:
Connections for SFRA tests on different transformer designs are given in a connection guide. this is not exhaustive, but has the bulk of transformer designs. Key to Useful Measurements A good measurement is one which can be repeated in the future. This requires that the result be independent of:
The M5100 provides good repeatable measurements which may be relied on for decision making. Case Studies Cases listed here cover common failures and show the value of SFRA and good repeatable measurements. Axial collapse - seven years after original SFRA measurements SFRA Support Material and FAQ's Short documents are available which include: Doble's input to standards development,
such as our paper to the IEEE Standards development is based on the technical requirements of the measurement and is
non-commercial. Contact Doble for the latest revisions. A results library is available to clients at http://www.doble.com/sfra_data/ which may be accessed via a username and password The Doble FRA User Group and Web Discussion Forum The Doble FRA user group meets twice a year to discuss applications, results and experiences. The Web Discussion Forum is available for discussion of results, procedures etc. If as a result of using this RSM and Reps Center you have any questions, comments or feedback we would appreciate hearing from you. Please contact the SFRA Product Manager at: SFRA_UG@doble.com SFRA Product Manager Office phone: ++1
(617) 926 4900 |
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