Explanation of the Function of Transformer Pressure Ring

Explanation of the Function of Transformer Pressure Ring

I. Installation Position
The pressure ring is installed at the top of the transformer high-voltage bushing (at the root of the outlet rod) or at the flange connection in the middle of the bushing. It is an accessory fitting of the bushing assembly.
(Image suggestion: A clear diagram or photo of a transformer high-voltage bushing with the pressure ring highlighted, showing its location at the top or flange.)

II. Core Functions

1. Uniform Electric Field Distribution
A potential gradient exists at the lead-out position of the transformer high-voltage bushing. The pressure ring uses its smooth annular structure to forcibly distribute the electric field evenly at high-potential points, eliminating the edge effect of metal components and preventing electric field concentration. This function effectively suppresses corona discharge, avoids accelerated aging of insulation materials due to partial discharge, and ensures the insulation strength of the bushing under power frequency voltage and lightning impulse voltage.
(Image suggestion: An illustration comparing electric field distribution with and without a pressure ring, showing smooth lines with the ring versus concentrated lines at edges without it.)

2. Mechanical Fixing and Sealing
The pressure ring is tightened onto the bushing conductor via threads, applying downward pressure to compress the sealing gasket at the top of the bushing, preventing transformer oil from leaking along the conductor. At the same time, it fixes the position of the outlet terminal, preventing connection loosening caused by vibration during equipment operation.
(Image suggestion: A cross-sectional view of the bushing top showing the pressure ring, conductor, and sealing gasket, with arrows indicating the pressing force.)

3. Current-Carrying Assistance
In some structures, the pressure ring acts as part of the conductive path, participating in the conduction of working current and ensuring stable and reliable contact surfaces for current-carrying.
(Image suggestion: A diagram showing the current flow path through the pressure ring as part of the circuit.)

III. Engineering Significance
In transformers with voltage levels of 110 kV and above, if no pressure ring is used for voltage equalization, strong corona discharge will occur at the root of the bushing, leading to radio interference, energy loss, and possibly insulation breakdown accidents after long-term operation. Therefore, the pressure ring is an essential component for ensuring the safe operation of high-voltage transformers.
(Image suggestion: A photo of a high-voltage transformer in operation, with a close-up of the bushing area, or a before-and-after comparison showing corona effects without a pressure ring vs. normal operation with one.)