What are unwanted heating currents in transformers known as?

Unwanted heating currents in transformers, known as eddy currents, arise due to the alternating magnetic field within the transformer core. When a magnetic field changes, it induces circulating currents within conductive materials, such as the metal core. These currents flow in loops, perpendicular to the direction of the magnetic field, and generate heat due to the resistance of the material. This heating effect can diminish the efficiency of the transformer and lead to energy losses.

Eddy currents are a critical consideration in the design of transformers and magnetic components. Engineers often take measures to minimize these currents—such as using laminated cores or materials with high electrical resistivity—to enhance performance and efficiency. The other options refer to different concepts; for instance, leakage currents relate to unintended current flow in non-ideal insulating systems, while friction currents do not directly pertain to electromagnetic phenomena in transformers. Type A currents is not a recognized term in this context. Thus, identifying eddy currents as the unwanted heating currents is accurate and reflects a foundational concept in electrical engineering related to transformer design and operation.