Shorting the primary winding of a transformer has different effects depending on its connection to a power source. If not connected, there is no impact on the transformer. When connected, the power source will be shorted, triggering circuit breakers or fuses to cut off power. A complete short circuit across the primary winding leaves the transformer unaffected but requires repair before reuse. In cases of partial short circuits, the unshorted winding may suffer damage, and even a few turns shorted can lead to overheating.