What Can a Variable Ratio Tester Measure?

Many people think that a transformer ratio tester is just to measure the transformer ratio, and then put it away after use. Engineers who have truly used HZTTR80A know that the testing function of this instrument goes far beyond just one variable ratio value, covering almost the entire set of indicators for evaluating the state of transformer windings.

Transformation ratio and turns ratio

The most essential function. The instrument applies a test voltage to the high voltage side, collects the response of the low voltage side, obtains the voltage ratio, and can switch to display the turns ratio with one click. The measurement range of the variable ratio is 0.9-10000, and the accuracy of the 80V test range reaches ± 0.1% within the range of 0.9-500. The resolution is 0.0001, and it is also capable of performing PT calibration in situations where accuracy is required. Z-type transformers are an exception - due to their unique winding structure, they can only display voltage ratios and cannot be converted to turns ratios.

Linking groups and vector relationships

There is a phase difference between the high and low voltage sides of a three-phase transformer, which is the core content of the connection group. The instrument measures and calculates the vector relationship between the primary and secondary voltages, automatically gives the group number (0-11), and displays the vector diagram in a graphical way on the screen, which is much more intuitive.

Polarity

Mainly used for testing single-phase transformers and PT (voltage transformers). Polarity reversal of PT can lead to incorrect direction determination of relay protection, so polarity verification is an essential step that cannot be skipped before PT operation.

Tap position

The instrument automatically calculates the current gear position of the tap changer based on the input rated tap changer, tap spacing, and measured transformation ratio, without the need for manual comparison with a table. This function saves a lot of time for the step-by-step inspection of on load tap changers.

Excitation current

Measurement range: 0-2000mA, accuracy: ± (1%+0.5mA). This indicator has limited significance when viewed alone, but for situations where there are very few turns of inter turn short circuit and the change in transformation ratio is not significant, abnormal excitation current is often the earliest indicator to expose the problem and is an important auxiliary criterion for transformation ratio testing.

Six functions, one instrument, complete wiring in one go, this is its greatest practical value.