TRT Standard Series True Three-Phase Transformer Turns Ratio Tester

TRT Standard Series

True Three-Phase Transformer Turns Ratio Tester

Test voltages from 1 to 250 V AC

Single-phase test voltage

True three-phase test voltage

The best turns ratio accuracy of 0.03%

Automatic vector group detection

Built-in tap changer control unit

Detailed analysis of test results using DV-Win software

• Interchangeable test leads with Three-phase Winding Ohmmeters & Tap Changer Analyzers TWA

Description

TRT Standard Series instruments are true three-phase, fully automatic test set specially designed for turns ratio, phase shift, and excitation current measurements of power, distribution and instrument transformers. TRT determines the transformer turns ratio by applying voltages across high voltage windings, accurately measuring voltages across the unloaded transformer windings, and then displaying the ratio of these voltages.

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

For a three-phase measurement, the test set is connected to all the three phases of a transformer to be tested. If specific vector diagrams are selected for different types of transformers, the TRT will run a specific test for each transformer type (i.e., single phase, Delta to wye/ star, Wye/Star to delta, Delta to delta, Wye/Star to wye/ star, Delta to zig-zag, etc.) without a need to switch the test hookup cables. In addition, it can perform the test with true three-phase test voltage, allowing testing any transformer type. Following the test, it displays a turns ratio, phase shift, and excitation current obtained with single-phase and/or true three-phase tests.

TRT lets users enter a transformer’s nameplate voltages for the turns ratio deviation calculation. This feature eliminates any error otherwise caused by an operator’s manual calculation. The TRT also compares the test result with the nameplate ratio and prints out the % of error for each test.

Operating conditions messages or error messages identify incorrect test conditions, abnormal operating condition or transformer problems. TRT has a very high ability to cancel electrostatic and electromagnetic interference in HV electric fields. It is achieved by a very efÏcient filtration. The filtration is made utilizing the proprietary hardware and software design solutions.

Application

The list of the instrument application includes:

• Turns ratio measurement
• Turns ratio deviation calculation
• Excitation current measurement
• Phase angle measurement
• Automatic vector group detection
• Verification of demagnetization process
• Magnetic balance test

Connecting TRT to Test Object

Three-Phase Transformer

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

Three-Phase Autotransformer

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

Single-Phase Transformer

Although a three-phase device, TRT is able to test singlephase transformers. Either a special cable set or a threephase cable set can be used for this purpose.

Single-Phase Autotransformer

Although a three-phase device, TRT is able to test singlephase autotransformers. Either a special cable set or a three-phase cable set can be used for this purpose.

Connecting TRT to a three-phase autotransformer

Phase-Shifting Transformer

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

Current Transformer

TRT can also be used for verifying turns ratio and polarity of current transformers (CTs). CTs are specially constructed transformers – they are instrument transformers with only one, or occasionally two primary turns. Larger number of turns is on the “X” (secondary) side of CTs. For that reason, when verifying CTs, the “X” test cables must be connected to the primary of a CT. If there are no primary terminals, the “X” cables should be slid through the CT core and short-circuited.

Benefits and Features

True Three-Phase Test Voltage

TRT (except TRT03) is a true three-phase turns ratio tester. Unlike other so-called “three-phase” testers that allow only connecting to three transformer phases at once, TRT also has the ability to output true three-phase test voltage, without any additional devices or modules. This allows testing any transformer type, including special designs such as phase shifting, arc furnace, rectifier transformers, etc. Besides measuring a turns ratio, it can also measure a voltage ratio of three-phase transformers, simulating real transformer working condition. By applying true three-phase test voltage, and by measuring induced three-phase voltage, TRT is able to determine actual phase shifts between HV and LV side voltages, and not just 0 or 180 degrees shift that is obtained by testing transformers with single-phase test voltage in turns.

Resolution

Excitation current measurement is important for determining problems in the transformer magnetic core. High measurement resolution enables better tracking of the current trend through all tap positions.

Interchangeable cables with TWA

TRT uses the same cable set as Three-phase Winding Ohmmeter & Tap Changer Analyzer TWA. This enables one-time cable setup for performing six tests: turns ratio, excitation current, phase angle, winding resistance, on-load tap changer DVtest, and demagnetization, thus making TRT and TWA one measurement system.

Automatic Vector Group Detection

Accuracy

The highest accuracy in the market, for all three parameters measured – turns ratio, excitation current, and phase angle – makes potential transformer irregularities and faults more visible.

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

DV-Win Software

The DV-Win software is included in the purchase price, and all its updates are free of charge. The software allows full control of TRT functions from a PC, creating and storing test plans, and downloading test results from the instrument’s internal memory. All results are presented both numerically and graphically, for an easy and convenient analysis. Test results can be directly exported to excel document. Customized test report can be generated, edited, saved in several file formats including pdf, and printed.

Magnetic Balance Test

This test helps in detecting possible problems in the transformer magnetic core. The test is completely automatic and requires no changes in cable setup comparing to turns ratio test. Results are presented both numerically and graphically.

Memory

There is enough memory in the TRT to store 200 test records. Each record consists of 50 test readings.

USB Flash Drive

Results can also be exported to a USB memory through integrated USB flash drive.

Tap Changer Control Unit

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

Built-in Printer

Built-in thermal printer, 112 mm (4.4 in) wide, is an optional accessory. Winding Resistance Measurement

Technical Data

Mains Power Supply

• Connection: according to IEC/EN60320-1; UL498, CSA 22.2
• Mains supply: 90 – 264 V AC, 50/60 Hz

Display

• LCD screen 20 characters by 4 lines;
• LCD display with backlight, visible in bright sunlight
• Input power: 200 VA (for TRT03 and TRT33) 250 VA (for TRT63)
• Fuse: 2 A / 250 V, type F, not user replaceable

Interface

• USB (standard)

Turns Ratio Measurement

• RS232 (optional)
• Range: 0.8 – 50 000
• Resolution: 5 digits
• Typical accuracy:

Data Storage

• TRT can store up to 10 000 test results

Dimensions and Weight

• Dimensions (W x H x D): 478 x 194 x 390 mm / 18.82 x 7.64 x 15.35 in
• Weight: 8 kg / 17.6 lbs (TRT03 and TRT33) 9 kg / 19.8 lbs (TRT63)

Environmental Conditions

• Operating temperature:
• 10 ºC – +55 ºC / +14 ºF – +131 ºF
• Storage & transportation temperature:
• 40 ºC – +70ºC / -40 ºF – +158 ºF

Excitation Current Measurement

• Range: 0 – 2 A
• Resolution: 0.0000 – 9.9999 mA 0.1 μA 10.000 – 99.999 mA 1 μA 100.00 – 999.99 mA 10 μA 1.0000 – 2.0000 A 100 μA
• Typical accuracy: ±(0.25% rdg + 0.5 mA)
• Humidity: 5% – 95% relative humidity, noncondensing

Warranty

• 3 years

Printer (optional)

• Built-in thermal printer

Phase Angle Measurement

• Range: 0 – 360º
• Resolution: 0.01º
• Typical accuracy: ±0.05º
• Paper width 112 mm / 4.4 in
• Printer operating temperature: 0 ºC – +50 ºC / +32 ºF – +122 ºF
• Printer density is guaranteed in this range: +5 ºC – +40 ºC / +41 ºF – +104 ºF 20 – 85% relative humidity, non-condensing

Test Voltages

• TRT63A: 1, 8, 40, 100, 250 V AC
• TRT63B: 1, 10, 40, 100, 250 V AC
• TRT63C: 1, 8, 40, 80, 250 V AC
• TRT33A: 1, 8, 40, 100 V AC
• TRT33B: 1, 10, 40, 100 V AC

Applicable Standards

• Installation/Overvoltage category: II
• Pollution degree: 2
• Safety: LVD 2014/35/EU (CE Conform) Standard EN 61010-1:2001
• EMC: Directive 2014/30/EU (CE Conform) Standard EN 61326-1:2006
• TRT33C: 1, 8, 40, 80 V AC
• TRT03A: 8, 40, 100 V AC
• TRT03B: 10, 40, 100 V AC

All specifications herein are valid at ambient temperature of + 25 °C and recommended accessories. Specifications are subject to change without notice.

• TRT03C: 8, 40, 80 V AC

Accessories

TRT Standard Series - Models

TRT63 (TRT63A, TRT63B, TRT63C)

TRT33 (TRT33A, TRT33B, TRT33C)

TRT03 (TRT03A, TRT03B, TRT03C)

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