In a major city’s main substation, engineers noticed unusual voltage fluctuations in a 110kV transformer. Suspecting a winding fault, they used a portable TTR tester to perform a comprehensive test. The results revealed a 2% deviation in the turns ratio on one phase, indicating a developing shorted turn. By identifying the issue early, the utility was able to schedule a controlled outage for repairs, avoiding a potential blackout that would have affected thousands of customers. The tester’s high accuracy and automatic testing features allowed the team to complete the assessment in under an hour, demonstrating how this tool is indispensable for proactive maintenance and preventing costly service disruptions.
How a Portable TTR Tester Helped Prevent a Substation Blackout
May 12, 2026
