What happens if the applied primary voltage is below the rated voltage on a transformer?

When the primary voltage applied to a transformer is below the rated voltage, the transformer experiences a decrease in its output power. This occurs because the turns ratio of the transformer is fixed, and a lower primary voltage results in a proportionately lower secondary voltage. As the voltage decreases, the ability of the transformer to deliver power effectively diminishes, which can lead to a situation where the load cannot be adequately supplied.

In addition, while the transformer can still operate when the input voltage is lower than the rated value, it may not be able to maintain its designed output voltage or current. The result can be insufficient power supply to the connected load, causing it to perform poorly or not at all.

Operationally, transformers are designed to function within a specific range of voltages. Operating under lower voltages may lead to increased winding losses and efficiency reductions, but it does not lead to an immediate shutdown of the transformer, nor does it overload the transformer. Thus, the most accurate consequence of applying a primary voltage below the rated voltage is that it may produce lower output power.