Transformer Testing

GD700A Automatic Turns Ratio Tester

Three-phase transformer turns ratio and voltage ratio tester with a range of 0.9 to 6000. Completes a full three-phase measurement in 15 seconds, with automatic vector group testing and support for Z-connected windings.

GD700A Automatic Turns Ratio Tester

Overview

Three-phase transformer turns ratio and voltage ratio tester with a range of 0.9 to 6000. Completes a full three-phase measurement in 15 seconds, with automatic vector group testing and support for Z-connected windings.

Application Scenarios

Turns ratio testing of transformers during semi-finished and finished productionRatio verification before a newly installed transformer is energisedPeriodic preventive ratio testing of transformers in serviceTap-changer condition checks and parallel-operation suitability checks

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Detailed Description

Overview: during the production of semi-finished and finished power transformers, before a newly installed transformer is put into operation, and in accordance with the preventive test code of the Ministry of Electric Power for transformers already in service, the turns ratio or voltage ratio has to be tested. The test checks the correctness of the transformer turns ratio, the condition of the tap changer, whether the transformer has an inter-turn short circuit and whether transformers can be operated in parallel.

A traditional ratio bridge gives readings that are not intuitive, requires conversion and can only measure phase by phase. The GD700A overcomes these shortcomings: operation is simple and intuitive, a three-phase ratio or turns ratio test is completed in one operation, and testing is fast and highly accurate.

Performance: the test range is wide, reaching 6000. Testing is fast, with a three-phase test completed in 15 seconds. Z-connected transformers can be tested, and the vector group test function is completed automatically. Protection is provided against high-voltage and low-voltage reverse connection and against transformer short circuit and inter-turn short circuit. Measurement results are output on the printer and the display uses a Chinese menu.

Technical parameters: the range is 0.9 to 6000. Accuracy is plus or minus 0.1% plus 2 digits from 0.9 to 500, plus or minus 0.2% plus 2 digits from 501 to 2000, and plus or minus 0.3% plus 2 digits from 2001 to 6000. The minimum resolution is 0.0001.

Technical Specifications

Measuring range0.9 – 6000
Accuracy±0.1% + 2 digits (0.9 – 500); ±0.2% + 2 digits (501 – 2000); ±0.3% + 2 digits (2001 – 6000)
ResolutionMinimum 0.0001
Three-phase test time15 seconds
Applicable windingsThree-phase ratio and turns ratio, including Z-connected transformers
Automatic functionsVector group test
ProtectionHigh-voltage and low-voltage reverse-connection protection; transformer short-circuit and inter-turn short-circuit protection
OutputPrinter output of measurement results with a Chinese menu display

Frequently Asked Questions

When is turns ratio testing required?
During the production of semi-finished and finished power transformers, before a newly installed transformer is put into operation, and in accordance with the preventive test code of the Ministry of Electric Power for transformers already in service. The test checks the correctness of the turns ratio, the condition of the tap changer, whether the transformer has an inter-turn short circuit and whether transformers can be operated in parallel.
How does the GD700A differ from a traditional ratio bridge?
A traditional ratio bridge gives readings that are not intuitive, requires conversion and can only measure phase by phase. The GD700A overcomes these shortcomings: operation is simple and intuitive, a three-phase ratio or turns ratio test is completed in one operation, and testing is fast and highly accurate.
What protection does the instrument provide?
The instrument provides protection against high-voltage and low-voltage reverse connection, and protection against transformer short circuit and inter-turn short circuit. Measurement results are output on the printer and the display uses a Chinese menu.

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