Advanced Transformer Diagnostics – SFRA, DFR

The latest session in our Testing Tactics series of webinars

Power transformers are critical components of power systems that play a vital role in the distribution and transmission of electrical energy. The failure of a transformer can result in significant disruption to power supply and can be expensive to repair or replace. Therefore, the maintenance and testing of transformers are crucial to ensure their safe and reliable operation. Advanced transformer diagnostic techniques have been developed to provide more detailed information about the condition of transformers and troubleshoot beyond typical transformer field testing. This webinar will focus on two such techniques: Sweep Frequency Response Analysis (SFRA) and Dielectric Frequency Response (DFR). 

The SFRA test is performed on a de-energized and demagnetized transformer and can detect a range of problems related to the core, winding, mechanical issues, such as internal faults, contact misalignment, and wear and tear. SFRA can detect changes in the frequency response of the transformer's complex network of resistance, inductance, capacitance, resulting from the overall winding geometry, core, and electrical connections. This also serves as a unique fingerprint of the transformer's mechanical structure. These changes can then be compared to previous baseline measurements to help field operators identify any internal movement and evaluate the mechanical integrity of the transformer system. 

The DFR test is performed on a De-energized transformer and is the measurement of capacitance and losses over multiple frequencies. By analyzing the dielectric response, DFR can detect insulation deterioration and moisture ingress within the transformer. Moisture that accumulates in the insulating system of a power transformer affects it in many ways such as limiting the loading capability, lowering the dielectric strength of the oil, and aging the cellulose which results in a reduced transformer life. DFR is a highly sensitive technique that can detect potential issues before they become catastrophic failures. 

The online seminar will provide an in-depth discussion on when, why, and how to perform the two tests. There will be best practice recommendations for each test and case studies will be presented over SFRA and DFR, along with an interpretation of the results. Together, these diagnostic techniques provide a comprehensive approach to transformer maintenance and testing, allowing for the early detection of faults and the implementation of appropriate maintenance strategies. The attendees to this online seminar will learn to utilize these advanced diagnostic techniques and how asset managers and technicians can gain valuable information about the condition of their transformers, identify potential issues before they lead to failures, and take proactive steps needed to maintain the reliability and safety of their power systems. 


This is a free webinar

All webinar attendees are eligible to receive 1 NETA CTD and 1 PDH or 0.1 CEU. 


Cade Patton

Applications Engineer

Cade Patton was born in Greenville, Texas. Following High School graduation in 2018, Cade went on to obtain his Bachelor of Science in Electrical Engineering from Texas A&M University at Commerce in 2022. During his senior year, Cade worked for Megger as an intern in the Technical Support Group. Once obtaining his Electrical Engineering degree, Cade transitioned into a role with Megger as an Application Engineer in the Substation Technical Support Group. Cade is well-versed in both site and laboratory conditions and is always eager to apply advanced math, physics, and hands on abilities. In his free time, Cade enjoys traveling and trying new foods, building computers, collecting sports memorabilia, and modifying sports cars.