Which of the following describes the result of applying a DC voltage to a single primary bushing transformer?

Applying a DC voltage to a single primary bushing transformer can lead to a condition known as a dead short. This occurs because transformers are designed to operate with alternating current (AC), which allows the magnetic field within the transformer to constantly change. The AC input creates a varying magnetic field that is essential for the operation of the transformer, allowing it to induce a voltage in the secondary winding.

When a direct current (DC) voltage is applied, it does not create a changing magnetic field. Instead, the transformer will initially attempt to draw current, but as the magnetic core saturates quickly (since a constant DC voltage cannot induce a varying field), it results in a very high level of current flowing through the windings, which typically exceeds the transformer’s capacity. This overwhelming flow can cause overheating, damage to the windings, or even a complete failure of the transformer, simulating a dead short condition.

In contrast, the other options do not accurately reflect the behavior of the transformer under DC voltage application. There would be no neutral or safe energization, and maximum output cannot be achieved because the required alternating characteristics for output are not present. Therefore, the result of using DC on such a transformer leads to the dangerous condition of a dead short.