TTR310E and TTR330A

TTR310E and TTR330A

Three-phase transformer turns ratio test set

This product is now obsolete and has been replaced by the TTRU3

  • Stand-alone or remote-control operation
  • Accurately measures ratio, phase deviation and excitation 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.

Technical Documents
Technical guide
A Guide to Transformer Ratio Measurements
Transformer Test Instrument Software Updates for TTR330A, MTO330A, MWA330A, DELTA4310A

The following components have been updated:

PowerDB ________________ V11.2.10 

MTOTestXP ______________ 2019.12.03.1

Delta Manual Control ______________   

Instrument Config ______ 1.0.20023.1919

Splash Screen __________ 1.0.21075.830

Factory Config _________ 1.0.21122.850

Megger Update Manager __ 1.0.21165.1032



- Megger recommends that you return your instrument annually for calibration verification.
- Any instrument returned for re-calibration will be updated with the latest firmware and software versions.
- Certified Factory Calibration is valid for one year.


Incorrect installation of updates or incomplete updates may cause the equipment to become unusable.

If damage occurs from improper updates, the customer may be responsible for repair costs.

Software updates for TTR330A, MTO330A, MWA330A and DELTA4310A

Download this zip file, extract, and run the executable.


256bit Hash:

763 MB | 02/08/2022
745.9 MB | 06/05/23
Update Instructions

Please download and read these instructions before performing the update.


623.9 KB | 06/05/23