EN
In today's power distribution systems, transformers are often overloaded. Conventional equipment can be quickly strained by unpredictable overload conditions, such as urban expansion, seasonal demand peaks and incorporation of renewable energy sources. The utility engineer, facility manager or facility developer knows that overload is a possibility, but not what will happen to their transformers. The solution is the cast resin transformer, a type of transformer designed to withstand harsh conditions. As a joint venture of Eaton (USA), Jiangsu Ryan Electric Co., Ltd. has produced a series of cast resin transformers that are easy to maintain and have high overload ability. Cast resin transformers are manufactured through the cooperation and participation of testing laboratories accredited by CNAS—and certified to standards such as IEEE, UL, CE, and ASTA, catering to the needs of clients from Microsoft to State Grid in more than 50 countries.
Superior Thermal Management and Heat Dissipation
This is where it all starts for a cast resin transformer, the ability to withstand overload. During overloads the internal temperature climbs fast and the copper losses (I²R) climb to the 2nd power. Cast resin transformers are cooled by direct heat transfer through solid epoxy encapsulation—unlike oil immersed designs, which become less efficient under sustained overload. Heat produced in the windings can be efficiently transferred to the outside surface of the windings by the high thermal conduct of the cast resin system, and the heat can be taken away from the windings by the natural air convection or forced air convection. To guarantee uniform resin distribution, avoid hot spots that would cause early insulation failure, Jiangsu Ryan Electric uses optimized winding geometry and precision casting technology in vacuum casting. This thermal efficiency provides the ability to operate our cast resin transformers continuously at 120-130% of rated capacity or higher, and to short term emergency overload conditions much higher without reaching critical temperature limits.
Robust Insulation System with High Thermal Class
All cast resin transformers have an insulation system, which is designed for durability. Our epoxy resin formulation has high thermal class ratings and has a significant margin over normal operating temperatures—usually Class F (155°C) or Class H (180°C). This high temperature endurance is very important in overload situations where windings temperatures may rise to or even exceed design limits. The superb dielectric properties of the resin hold true at high temperature, meaning that partial discharge is avoided and electrical integrity is maintained. Furthermore, the encapsulation process itself, which is performed with VPI (Vacuum Pressure Impregnation) technology—assures the complete multiplying of resin through all the layers of windings, thus eliminating the presence of voids where moisture may accumulate or where corona discharge may take place. Cast resin transformers undergo type testing at a dedicated test bay here at Jiangsu Ryan Electric, including temperature rise tests and short circuit withstand tests, to ensure that every cast resin transformer conforms to IEC 60076 and IEEE C57 standards, ensuring overload performance, providing engineers with peace of mind about the resilience of their system.
Elimination of Fluid-Related Failure Mechanisms
The maintenance-free nature of the cast resin transformer during overloads is one of the main reasons for using it. During an extended overload, oil-immersed transformers may experience a number of failure modes: oil decomposition reduces the cooling capacity, which results in the production of flammable gases; sludge formation insulates the internal components, causing a rise in temperature; and degradation of seals leads to leakage and moisture entering the transformer. These are completely eliminated with the cast resin transformer. Since there is no oil to degrade, no gaskets to fail and no breathing system to maintain, the chances of cascading failures during overload events are drastically reduced. The superior short circuit withstand capability is also due to the solid encapsulation, which will make windings resist the huge electromagnetic force generated under short circuit conditions. The cast resin transformer developed by Jiangsu Ryan Electric can withstand repeated overload and fault, and is optimized in the areas of axial and radial clamping, so that the winding is no longer prone to damage after repeated use and the lifetime is as long as several decades.
Smart Monitoring and Predictive Protection
The cast-resin transformer, after all, is a sturdy transformer but today, the grid needs intelligence, as well as strength. The cast resin transformer produced by Jiangsu Ryan Electric can be equipped with partial discharge monitoring system and embedded temperature sensor so as to have the monitoring ability of the transformer condition in real-time. These sensors continuously monitor the temperature of windings and conditions of the insulation, and alert to potential problems before they become failures. If an overload is detected, the monitoring system will be able to interact with upstream protection devices, enabling load shedding or dynamic ratings to be implemented to maximize transformer life. This intelligent solution will turn the cast resin transformer from a passive element into an active element in the grid stability. Our research and development team is constantly improving materials and monitoring algorithms and our solutions can withstand overloads and offer the information to manage them effectively. Whether in precision manufacturing or project overseas, our cast resin transformers are the ultimate in durability, intelligence, and efficiency, proving maintenance-free is not unprotected.