If a transformer fails the Transformer Turns Ratio (TTR) test, several steps should be taken to identify the cause and correct the issue:

1. Retest the Transformer: Perform the TTR test again to rule out testing errors, such as improper connections, faulty test equipment, or incorrect test procedures.

2. Inspect the Transformer: Visually inspect the transformer for obvious signs of damage or deterioration, such as burnt insulation, corrosion, or oil leakage.

3. Check for Winding Problems: A failed TTR test may indicate issues with the transformer windings, such as:

• Shorted Turns: This occurs when insulation between turns fails, causing a short circuit.
• Open Circuit: A broken connection in the windings can lead to an open circuit, altering the turns ratio.
• Incorrect Tapping: Check if the tap changer is correctly positioned or functioning.

4. Core Problems: The transformer’s magnetic core may be damaged or malfunctioning, leading to an improper turns ratio.

5. Secondary Tests: Perform additional diagnostic tests, such as winding resistance tests or insulation resistance tests, to further investigate the issue.

6. Repair or Replace the Transformer: If a fault is confirmed, the transformer may need to be repaired or replaced, depending on the severity of the issue.

Addressing these steps helps to diagnose and rectify issues after a failed TTR test, ensuring the transformer operates reliably and efficiently.