Ensuring Transformer Efficiency: Cooling Techniques and Short-Circuit Considerations

Power transformers play a crucial role in electrical systems, and their efficiency largely depends on effective cooling and robust design. Keeping the core and tank wall below specific temperature thresholds is vital to prevent oil gassing, a process that can degrade transformer performance. In larger transformers, engineers often incorporate vertical oil ducts alongside horizontal ducts within the winding sections to enhance cooling. This strategic placement ensures optimal oil flow, which is critical for maintaining safe operating temperatures.

To facilitate adequate oil circulation, the design of horizontal ducts is key. These ducts should be wide enough to allow for seamless oil movement, with a recommended thickness of at least 8% of the section width. This asymmetrical arrangement of ducts helps create a more efficient oil flow, thereby improving the overall heat dissipation from the windings. The effectiveness of these cooling techniques is further enhanced by directed forced oil flow, which improves surface heat transfer.

However, increasing oil velocity does not always equate to better cooling. Research indicates that while the surface heat transfer improves with higher oil velocities, there is a point of diminishing returns. Beyond a certain velocity, additional pumping can lead to unnecessary increases in energy consumption without significant gains in temperature reduction. Therefore, careful assessment of oil flow rates is essential for optimizing transformer design.

Transformers also face various electrical stresses throughout their operational life, including transient inrush currents, steady load currents, and transient short-circuit currents. During short-circuit events, the mechanical forces exerted on winding conductors can exceed their normal operating limits, potentially leading to physical deformation. This risk is heightened as the transformer ages and insulation materials become more brittle. A well-designed transformer must account for these stresses to ensure durability and reliability.

The design and maintenance practices surrounding cooling systems and mechanical structures are crucial in minimizing the likelihood of dielectric breakdown during short-circuit incidents. Implementing robust structural designs and effective cooling methods not only enhances the longevity of transformers but also reduces the risk of catastrophic failures, ensuring consistent performance in electrical networks.