Detailed Explanation of Transformer Basic Structure

In power systems, transformers play a crucial role, acting as the “bridge” for electrical energy transmission and distribution by enabling voltage conversion. For electrical engineers, a thorough understanding of a transformer's basic structure is fundamental to grasping its operating principles, maintenance procedures, and troubleshooting. Below, we will dissect each component of a transformer in detail.

I. Core Magnetic Circuit—Iron Core   The iron core, as the magnetic path of the transformer, bears the responsibility of conducting alternating magnetic flux. It is constructed by laminating silicon steel sheets with thicknesses of 0.35mm or 0.5mm, a design aimed at minimizing eddy current losses and hysteresis losses. In terms of shape, small transformers typically employ square core columns, while larger capacity units often utilize multi-level trapezoidal structures to optimize magnetic field distribution and enhance magnetic permeability. Windings are precisely fitted around these core columns, forming the core framework for transformer operation.

II. Electrical Energy Transmission Pathway—Windings   Windings constitute the primary circuitry of a transformer, responsible for electrical energy input and output. They are generally wound with insulated copper wire and can be categorized into concentric and interleaved configurations based on their arrangement. Power transformers commonly employ concentric winding layouts, where the low-voltage winding is placed directly against the core, while the high-voltage winding is nested around it. The winding connected to the power source is termed the primary winding, and the one connected to the load is the secondary winding. Energy transfer between them is achieved through electromagnetic induction.

III. Safety Shield and Cooling Powerhouse—Oil Tank   The oil tank is fabricated using steel plate welding techniques, forming a tightly sealed container. It is filled with transformer oil, which serves a dual purpose: first, it effectively dissipates heat generated by losses, ensuring stable operation; second, its superior insulating properties prevent electrical breakdown accidents. The entire core and windings are immersed in this protective oil layer, ensuring both safety and efficiency.

IV. Efficient Cooling System — Cooling Devices   To address the specific needs of large-capacity transformers, designers incorporate cooling tubes into the tank walls, further enhancing natural convection heat dissipation. For higher-power equipment, forced-circulation coolers are additionally configured. These mechanically drive oil circulation to achieve rapid cooling, ensuring reliable operation under prolonged high loads.

V. Electrical Connection Hub—Insulating Bushings   To safely route winding leads to external circuits while ensuring secure fixation, transformers are equipped with specialized insulating bushings. These bushings not only provide excellent electrical insulation but also withstand mechanical stress, serving as critical components connecting internal windings to external circuits.

VI. Flexible Voltage Regulation Mechanism—Tap Changer   The tap changer is a vital device for voltage adjustment, typically connected to the taps of the high-voltage winding. Its adjustment range is approximately ±5% of the rated voltage, meeting voltage requirements under various operating conditions. Based on operating methods, tap changers are categorized into no-load tap changers and on-load tap changers. The former requires adjustment during power outages, while the latter enables smooth switching under load conditions.

VII. Oil Quality Protection System — Oil Expander and Related Components

1. Oil Expander (Oil Reservoir): A cylindrical container positioned above the tank, connected to it via piping. Its primary function is to slow the oxidation and aging process of transformer oil, extending its service life. When temperature changes cause oil volume expansion or contraction within the tank, the oil conservator acts as a buffer, maintaining stable system pressure.

2. Gas Relay: A sensitive device installed on the connecting pipeline between the oil conservator and the tank. It rapidly activates and issues an alarm signal upon detecting gas generated by internal transformer faults, providing critical protection.

3. Desiccant Breather: Located at the bottom of the oil conservator, it contains desiccants like calcium chloride or silica gel to absorb moisture from incoming air, preventing dampness from degrading oil quality.

4. Oil Purifier: A cylindrical tank made of welded steel plates, mounted on the oil tank side. Filled with silica gel particles, it adsorbs moisture and impurities from the oil during transformer operation, purifying the oil and extending its service life.

5. Oil Level Gauge: Installed on one side of the oil reservoir, it features red lines marking the minimum and maximum oil levels. Observing oil level changes provides a general indication of oil temperature and whether new oil needs to be added.