Advanced Series

Advanced Series

TRT Advanced Series

The TRT is based on state-of-the-art technology and uses the most advanced technique available today. The test equipment can be used to test both single-phase and three-phase transformers, both with and without tap changer in accordance with the requirements of IEC 60076-1.

For a three-phase measurement, the test set is connected to all three phases of a transformer. If specific vector diagrams are selected for different types of transformers, the TRT will perform a specific test for each type of transformer (i.e. single phase delta to star, star to delta, delta to delta, star to star, delta to zigzag, etc.) without the need to change the test connection cables. In addition, you can test with the three-phase test voltage, allowing you to test any type of transformer. After the test, the instrument displays a ratio of turns, phase shift and excitation current obtained with single and / or three phase test voltages.

The TRT allows users to enter the voltages from the nameplate for calculation of the turn ratio deviation. This function eliminates any error caused by the operator's manual calculation. The TRT also compares the test result to the nameplate ratio and prints the percentage (%) of error for each test.

Operating condition or error messages identify incorrect test conditions, abnormal operating problems, or transformer problems. The TRT has a very high capacity to cancel electrostatic and electromagnetic interference in HV electrical fields. This is achieved through very efficient filtration. The filtration is done using the proprietary hardware and software design solutions.


The list of applications of the instrument includes:

Transformer ratio measurement

Calculation of the gear ratio deviation

Measurement of the excitation current

Phase angle measurement

Automatic vector group detection

Verification of the demagnetization process

Magnetic balance test

Connecting the TRT to the test object

Three-phase transformer

The TRT is programmed to automatically test the loop ratio, phase shift and excitation current of power and distribution transformer types defined by IEC/IEC, IEEE and ANSI standards. Using two sets of four wires, all primary and secondary side bushings are connected only once.

The TRT is also programmed to automatically test the loop ratio, phase shift and excitation current of autotransformer types defined by IEC/IEC, IEEE and ANSI standards. Using two sets of four wires, all primary and secondary side bushings are connected only once.

Single-phase transformer

Although it is a three-phase device, the TRT is capable of testing single-phase transformers. A part of the three-phase transformer / autotransformer cable set can be used for this purpose.

Single-phase autotransformer

Although it is a three-phase device, the TRT is capable of testing single-phase autotransformers. A part of the three-phase transformer / autotransformer cable set can be used for this purpose.

Phase shifting transformers

The presence of the three-phase voltage allows the TRT to test any type of transformer, even those with irregular vector groups, including phase shifting transformers.

Current Transformer

The TRT can also be used to check the ratio of the loops and the polarity of current transformers (CTs). CTs are specially constructed transformers - instruments with only one, or occasionally, two primary windings. Most turns are on the "X" (secondary) side of the CTs. Therefore, when checking CTs, the test leads "X" should be connected to the primary side of a CT. If there are no primary terminals, the cables "X" should be slid through the CT core and short-circuited.

Advantages and features

The TRT can generate the single-phase test voltage using the maximum value of 500 V AC. This provides more accurate measurements on large power transformers and autotransformers used in power generation and transmission.

True three-phase test voltage

The TRT is a three-phase transformer ratio meter. Unlike other so-called "three-phase" testers that allow only three transformer phases to be connected at a time, the TRT also has the ability to produce a three-phase test voltage, without the use of other devices or additional modules. This allows for testing any type of transformer, including special designs such as phase shifting, arc furnace, rectifier transformers, etc. In addition to measuring a transformer ratio, it can also measure a voltage ratio of three-phase transformers. By applying a three-phase test voltage and by measuring the induced three-phase voltage, the TRT is able to determine the actual phase changes between the HV and LV sides (and not just the 0 or 180 degree change that is obtained by testing transformers with the single-phase transformer ratio test).


The highest accuracy on the market for all three measured parameters - ratio, excitation current and phase angle - makes potential transformer irregularities and defects more visible.

Vector group detection

The TRT is able to automatically detect the vector group of three-phase transformers and auto-transformers. This is possible with and without PC software.

Tap changer control unit

The TRT has a built-in tap changer control unit, which allows remote operation of the on-load tap changer. A single operator can perform complete tests very quickly.

Large touch screen

The TRT comes equipped with a large 10.1" (TRT500 model) or 7" (TRT400, TRT250 and TRT100 models) graphic touch screen. This makes test preparation, test execution and analysis of test results as easy as possible. The test template can be prepared and saved in the office, making it possible to run the test in the field with just a few clicks. All test results are presented both numerically and graphically, for easy and convenient analysis.

Interchangeable cables with TWA

The TRT uses the same cable set as the TWA Three-Phase Winding Analyzer. This allows a unique cable configuration to perform 8 tests: turn ratio, excitation current, phase angle, vector group detection, magnetic balancing, winding resistance, tap changer analysis on load - DVtest, and demagnetization, thus making the TRT and TWA a measurement system.

Connecting the TRT500 and TWA500 to a three-phase transformer

Connecting the TRT400 and TWA400 to a three-phase transformer

Automated testing at multiple OLTC positions

The built-in tap changer control unit allows fully automatic turn ratio testing at multiple OLTC positions. The TRT is able to control the entire measurement process and change taps automatically.


The measurement of the excitation current is important for determining problems in the magnetic transformer core. The high measurement resolution allows better monitoring of the current trend across all tap changer positions.

The magnetic balance test

This test helps to detect possible problems in the magnetic transformer core. The test is fully automatic and does not require changes in the cable configuration compared to the winding ratio test. The results are presented both numerically and graphically.


The TRT has an internal SD card with 8 GB of memory space. This allows you to save tens of thousands of test results and templates.

USB Flash Drive

The results can also be exported to a USB stick via an integrated USB flash drive for further analysis and processing with the powerful Amperis-Win software. Test templates created in the Amperis-Win software can be imported from a USB stick via this integrated USB flash drive. Built-in printer A built-in 112 mm thermal printer is an optional accessory.

Amperis-Win Software

The Amperis-Win software is included in the purchase price, and all updates are free of charge. The software allows full control of the TRT functions from a PC, as well as the creation and recording of test templates. All results are presented numerically and graphically, for easy and convenient analysis. Test results can be exported directly to an Excel sheet. The customized test report can be generated, edited, and saved in various file formats.

Download the catalogue: Advanced Series.

Download the catalogue of Advanced Series.

If you want to acquire Transformer ratio meters with quality, you can also consult prices of Transformer ratio meters.

If you have any doubts or need advice from our engineers, don't hesitate to contact us and we will be pleased to help you. You can also call us at (+34) 982 20 99 20.