When does a transformer exhibit better efficiency?

A transformer exhibits better efficiency under high load conditions because it is designed to operate optimally when supplying power close to its rated capacity. At high loads, the losses associated with the transformer, such as copper losses (which happen due to resistance in the windings) and core losses (related to magnetic hysteresis and eddy currents), are more effectively outweighed by the output power being delivered.

Transformers are engineered for specific load scenarios; thus, when operating within their designed load range, they perform with maximum efficiency. Conversely, operating under low load conditions tends to increase relative losses, as fixed losses become more significant compared to the output power. Increased frequency currents can influence loss characteristics but primarily impact the design of transformers rather than directly translating to efficiency at specific load conditions. Similarly, while the quality and quantity of magnetic material enhance performance, it doesn't singularly determine efficiency as loading does.

Overall, maximizing the load up to the transformer's rated capacity is the most effective way to enhance efficiency, making high load conditions the ideal scenario.