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A Comparison of Vanguard’s ATRT Series of Transformer Turns-Ratio Testers

Vanguard ATRT-03 Automatic Three Phase TTRWhen the windings of a transformer develop shorts, opens or other defects, the effective number of turns may change. This may result in the change of the ratio of the windings and affect the power conversion of the transformer. Ratio changes can cause severe power losses and instability in the electrical system. It is a good idea to regularly test the ratio of transformers to ensure efficient power conversion. Regular preventive maintenance also allows technicians to spot developing faults and stop them before they get out of hand.

To help you diagnose winding problems, consider getting a turns-ratio meter. This device can accurately measure turns ratio to help you determine any deviation from the baseline data. If you are looking for the most suitable tester for your electrical facility, consider Vanguard testers. The Vangaurd ATRT-03, ATRT-03A and ATRT-03A Series 2 are some of the popular models. Here is a comparison of the testers to help you decide which suits you best.

Vanguard ATRT-03 Automatic Three Phase TTR

The ATRT-03 is a three-phase, transformer turns-ratio tester. The ATRT-03 is lightweight, rugged, and portable, and is designed for transformer testing at utility power substations. The ATRT-03/03A determines the transformer turns ratio by accurately measuring the voltages across the unloaded transformer windings and then displaying the ratio of these voltages (ratios range from 0.8 to 15,000). The ATRT-03A calibrates each measurement to ensure the turns-ratio accuracy.

Vanguard ATRT-03 S2 Automatic Three Phase TTR

The ATRT-03 S2 Automatic, Three-phase Transformer Turns Ratio Tester determines the transformer turns ratio using the IEEE C57.12.90 measurement method. The ATRT-03 S2 Automatic Three Phase Transformer Turns Ratio Tester outputs an excitation test voltage to the transformer primary windings. The induced secondary voltage is sensed and the transformer turns ratio is calculated. 

Vanguard ATRT-01B Battery Powered Single Phase TTR

The transformer turns-ratio is determined by precisely measuring the voltages across the unloaded transformer windings. The ATRT-01B Battery Powered Single Phase TTR measures circuitry, and self-adjusts before each measurement to ensure turns-ratio accuracy.


  • Single Phase TTR 
  • Measure turns-ratios from 0.8 to 15,000 
  • Calculate turn-ratio in percentage 
  • Measure and displays winding excitation current and polarity 
  • Stand alone or computer controlled 
  • ATRT-01 – line powered unit / ATRT-01B battery powered unit


Protec Equipment Resources is ready to provide you with the electrical test equipment you need for preventive maintenance. We offer various options to help you acquire test equipment that suits your budget and needs. Please call us at 1-866-352-5550 to learn more about our services.

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