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Handheld TTR

  • » Fully automatic; fast; easy-to-use; robust; lightweight
  • » Battery powered
  • » Tests turns ratio, excitation current, and polarity
  • » Simple, one-button operation
  • » Quick-start guide on front panel
  • » Operator-selectable languages


The Megger TTR25 is an automatic hand-held battery operated transformer turns ratio test set. It is used to measure the turns ratio, excitation current and polarity of windings in single- and three-phase distribution and power transformers (tested phase by phase), potential & current transformers, and tapped transformers.

The unique design of the TTR25 allows the user to operate the test set while holding it in one hand. It effectively eliminates the user from having to kneel or bend down to operate the instrument and speeds up testing time. Realizing the extreme environments in which the TTR25 must operate, special attention has been paid to making it extra rugged, with a high impact, shock resistant case, yet incredibly lightweight at a mere 870 g (1.9 lbs).

Its design makes this instrument well suited for use in a variety of harsh environments. The TTR25 is particularly suited for testing in substations, transformer-manufacturing environments, and meter shops. It features a high-contrast, backlit LCD screen which can be seen in bright or ambient light.

This unit measures a high turns ratio of 20,000:1 accurately with the lowest excitation voltage. The excellent repeatability of the TTR25 helps the users to determine the condition of transformers under test. It is designed for simple, one button operation with the measured results displayed directly on the easy to read LCD or printed to the optional printer. The TTR25 needs no additional software and comes ready to use complete out of the box.

TTR®300 Series

3-Phase Transformer Turns Ratio Test Sets

  • » Stand-alone or remote-control operation
  • » Accurately measures ratio, phase deviation and exciting current
  • » Field upgradeable without compromise to calibration
  • » Built-in capability for storing and downloading test results in an XML format, via RS-232, Ethernet or USB ports (depending on model)
  • » Works in the presence of high interference/high voltage
  • » Highest ratio measurement (45,000:1); highest accuracy (0.1%)
  • » Displays % error vs. name plate with pass/fail limits


The TTR300 Series of three-phase transformer turns ratio test sets are designed to measure the turns ratio of power, instrument, and distribution transformers in a substation or manufacturing environment. A rugged and robust design makes these instruments well suited for use in a variety of harsh environments. Our leads are specially designed to provide the necessary flexibility needed in cold weather.

The TTR300 Series are ideal for use by power transformer manufacturers. Their unique testing procedures and storage capability allows an operator to set up and test difficult three-phase transformers (with multiple tap changers and bushing CTs) in a fraction of the time than it used to take with other TTRs. This test also includes a pass/fail limit of individual ratios.

The TTR300 Series also measure the phase deviation of the transformer primary versus secondary. This quickly indicates problems in the transformer such as partial shorted turns and core faults. This measurement is also useful in verifying phase errors in all types of PTs and CTs.

Each unit comes equipped with a remote-control switch for single person testing. This allows the operator to test transformers with LTCs very quickly.

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