A lower than normal output voltage in a transformer might indicate what issue?

A lower than normal output voltage in a transformer is often indicative of a partial short in the secondary winding. When there is a partial short, it effectively reduces the voltage output because some of the electrical energy is bypassed instead of being delivered to the load as intended. This condition can create a scenario where only a portion of the winding contributes to the overall output, leading to a decrease in voltage.

It's important to understand how transformer windings function. In a properly operating transformer, energy is transferred efficiently between the primary and secondary windings via magnetic coupling. Any issue that disrupts this coupling or causes a portion of the winding to become ineffective will alter the expected output voltage.

While other issues like an open circuit in the primary winding or an incorrect voltage supply can also cause problems with transformer performance, they typically lead to complete loss of output or other symptoms rather than merely reducing the voltage. An overloaded transformer can cause overheating and may lead to other effects, but it often does not solely result in lower output voltage unless combined with other issues. Thus, the scenario of a partial short directly correlates to the symptom of a lower than normal output voltage, making it the most fitting explanation.