The iron core in a transformer is a crucial component, playing multiple roles. Here is an introduction to the transformer core:

　　The core is the main magnetic circuit of the transformer, its primary function being to conduct magnetism. It converts electrical energy from the primary circuit into magnetic energy, and then magnetic energy back into electrical energy for the secondary circuit. The core is usually made of stacked silicon steel sheets with a high silicon content. These silicon steel sheets are coated with insulating paint to reduce eddy current losses. The core structure typically includes core columns and yokes; the windings are placed on the core columns, and the yokes connect the core columns to form a closed magnetic circuit.

　　In addition to being part of the transformer’s magnetic circuit, the core also serves as the mechanical framework of the transformer. It supports the windings and secures other internal components. The weight of the core accounts for a significant proportion of the transformer’s total weight. For large transformers, the weight and volume of the core are considerable.

　　During transformer operation, the core generates a certain amount of heat, so heat dissipation measures are necessary. For oil-immersed transformers, oil channels are often provided between the core laminations to enhance heat dissipation; in dry-type transformers, air ducts are often installed in the core columns and yokes for heat dissipation.

　　It is important to note that the core must be reliably grounded to prevent sparking due to potential differences, which can damage the transformer’s insulation. At the same time, the core grounding must be a single-point ground to avoid forming a circulating current, which can cause local overheating and damage.

　　In summary, the iron core in a transformer is a complex and critical component, and its design and manufacture are crucial to the performance and reliability of the transformer.