110kV Oil-Immersed Transformer Technical Description A 110kV oil-immersed transformer is a critical component in high-voltage power transmission and distribution systems, designed to efficiently step up or step down voltages while ensuring reliable performance and longevity. These transformers are widely used in substations, industrial plants, and utility networks due to their robust construction, high efficiency, and ability to handle large power capacities. Design and Construction The transformer consists of a magnetic core made of high-grade silicon steel laminations to minimize hysteresis and eddy current losses. The core supports primary and secondary windings, which are typically constructed from copper or aluminum conductors insulated with high-temperature-resistant materials. The entire active part is immersed in insulating oil, which serves multiple purposes: 1. Insulation: The oil provides dielectric strength, preventing electrical breakdown between windings and the grounded tank. 2. Cooling: Oil circulates naturally or via forced circulation (with radiators or pumps) to dissipate heat generated during operation. 3. Protection: The oil inhibits oxidation of internal components and helps detect faults through dissolved gas analysis (DGA). The tank is hermetically sealed or equipped with a conservator (expansion tank) to accommodate oil volume changes due to temperature fluctuations. Key Features and Performance - Voltage Rating: Designed for 110kV primary voltage, with secondary voltages tailored to application requirements (e.g., 11kV, 33kV). - Power Capacity: Ranges from several MVA to over 100MVA, depending on load demands. - Efficiency: High efficiency (typically > 99%) achieved through low-loss core materials and optimized winding design. - Cooling Methods: Common classifications include ONAN (Oil Natural Air Natural) or ONAF (Oil Natural Air Forced) for larger units. - Protection: Equipped with Buchholz relays, pressure relief devices, and temperature monitors to safeguard against internal faults. Applications 110kV oil-immersed transformers are deployed in: - Grid Substations: Interconnecting transmission networks. - Renewable Energy Plants: Integrating wind or solar farms into the grid. - Industrial Facilities: Powering heavy machinery or large-scale processes. Maintenance and Safety Routine maintenance includes oil testing, insulation resistance checks, and thermal imaging to detect hotspots. Fire safety measures (e.g., bund walls, fire-resistant oil) are critical due to the flammable nature of mineral oil. Advantages - Durability: Long service life (25+ years) with proper maintenance. - Load Handling: Superior performance under continuous and peak loads. - Cost-Effectiveness: Lower lifetime costs compared to dry-type transformers for high-voltage applications. Environmental Considerations While mineral oil is common, biodegradable alternatives (e.g., ester-based oils) are gaining traction to reduce environmental risks. In summary, the 110kV oil-immersed transformer remains a cornerstone of modern power systems, balancing performance, reliability, and scalability for diverse electrical infrastructure needs.