Which of the following methods can be used to determine if a transformer winding has some of its turns shorted together?

• A. Check if the transformer core is made of silicon steel.
• B. Measure the voltage across the winding and expect it to be $0$ if turns are shorted.
• C. Measure the winding resistance and compare it to the expected value; a significantly lower resistance may indicate shorted turns.
• D. Observe if the transformer produces a humming sound during operation.

Answer: (C)

Verified step by step guidance

1. Understand that shorted turns in a transformer winding create a low-resistance path, which affects the winding's electrical characteristics.
2. Recall that measuring the voltage across the winding alone is not reliable for detecting shorted turns because voltage depends on the applied input and load conditions.
3. Recognize that the core material (such as silicon steel) does not directly indicate the presence of shorted turns; it mainly affects magnetic properties and losses.
4. Focus on measuring the winding resistance using an ohmmeter or similar device; compare the measured resistance to the expected resistance value for the winding.
5. Interpret the results: if the measured resistance is significantly lower than the expected value, it suggests that some turns are shorted together, creating a shorter electrical path.