The Turns Ratio Test (TTR Test) is a diagnostic test performed on transformers to verify the accuracy of the turns ratio between the primary and secondary windings. This test ensures that the transformer is functioning correctly and meets design specifications.

Purpose of the TTR Test:

1. Verify Winding Ratio: Confirms the proper voltage transformation.

2. Detect Issues: Identifies winding short circuits, open circuits, incorrect connections, or core problems.

3. Ensure Proper Functioning: Helps maintain efficiency and prevent failures.

Procedure of the TTR Test:

1. Test Setup:

A specialized TTR meter is used.

The transformer must be de-energized and isolated.

The test is performed phase by phase.

2. Measurement:

A low-voltage AC signal is applied to the primary winding.

The induced voltage in the secondary winding is measured.

The ratio of primary to secondary voltage is calculated.

3. Comparison with Nameplate Ratio:

The measured turns ratio should match the nameplate ratio within an acceptable tolerance (usually ±0.5% to ±1%).

Interpretation of Results:

Pass: If the measured ratio is within tolerance, the transformer is functioning properly.

Fail: A deviation beyond tolerance indicates potential issues such as:

Shorted turns

Incorrect winding connections

Open circuits

Core damage