What could be the reason for reading 0 V across the secondary winding of a transformer when 110 V AC is applied to the primary winding?

Reading 0 V across the secondary winding of a transformer when 110 V AC is applied to the primary winding typically indicates that the primary winding is not complete or connected, which would cause no magnetic flux to be induced in the secondary. In a transformer, the primary winding generates a magnetic field when an AC voltage is applied. This magnetic field is then coupled to the secondary winding, inducing a voltage proportional to the turns ratio between the two windings.

If the primary winding is open, it means that the circuit is broken, preventing any current from flowing through the primary. Consequently, there would be no magnetic field generated, and as a result, no voltage would be induced in the secondary winding. This leads to the observation of 0 V at the secondary.

In contrast, if the secondary winding were grounded, you would still expect to see some voltage depending on the grounding method and load applied. Similarly, an overloaded transformer would usually still produce some output voltage unless extreme conditions led to failure. Therefore, the situation where 0 V is detected directly correlates with an open primary winding, confirming the reasoning behind the observed measurement.