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Views: 0 Author: Site Editor Publish Time: 2026-06-25 Origin: Site
With the continuous expansion of power transmission networks to support renewable energy grid integration, industrial development, and inter-regional power distribution, 230kV oil-immersed power transformers, as the core hub of the power transmission and distribution system, directly affect the safety of the entire power grid through their operational stability and efficiency. To meet stringent power transmission requirements, transformers must possess extremely high electrical strength, mechanical strength, and thermal stability. This article will focus on the advanced manufacturing processes of high-voltage power transformers and analyze in depth the key technical specifications and manufacturing requirements of 230kV oil-immersed power transformers from the aspects of core, winding, and insulation structure.
The transformer core is responsible for transmitting magnetic flux. Its design and materials directly determine the transformer's no-load loss and noise level, while minimizing energy loss. Since core losses are continuous during operation, optimizing core performance directly improves transformer efficiency and reduces operating costs.
For 230kV high-voltage transformers, the core design must meet extremely high process standards:
The core must use high-permeability, low-loss, high-quality cold-rolled grain-oriented silicon steel sheets (CRGO), and undergo precise longitudinal and transverse shearing processes to ensure burr-free edges, reducing local eddy current losses.
To minimize magnetic resistance at the joint, 230kV transformer cores commonly employ a step-laminated lamination process. This structure significantly optimizes magnetic flux distribution, reducing the transformer's no-load current and no-load loss by 10% to 15%, while effectively suppressing electromagnetic noise.
The core columns and yoke are secured using high-strength straps, clamps, and non-magnetic steel strips. The core surface is coated with an oil-resistant and heat-resistant insulating varnish, which not only prevents short circuits between laminations but also effectively secures the structure, preventing loosening or vibration caused by electromagnetic forces during transportation and long-term operation.
The winding system is the core of every power transformer. Its ability to withstand rated current and potential short-circuit current impacts over long periods determines its electrical performance and its capacity to withstand mechanical stresses caused by fault currents.
The winding design of a 230kV transformer requires a perfect balance between conductivity, heat dissipation efficiency, and mechanical resistance to alternating stress.
Winding Structure Type: Depending on the voltage level and capacity, 230kV high-voltage windings typically employ either a continuous or interleaved structure. Interleaved windings, by altering the electrical connection sequence of the conductors, significantly increase the longitudinal capacitance of the winding, resulting in a more uniform distribution of lightning impulse voltage within the winding and greatly enhancing the transformer's surge resistance.
Conductor Material and Transposition Technology: High-purity oxygen-free copper conductors are selected. To reduce surface current effects and eddy current losses caused by high currents, combined conductors or continuously transposed conductors (CTC) are typically used. CTC technology not only reduces circulating current losses but also improves winding space utilization and optimizes heat dissipation.
Enhanced Short-Circuit Resistance: During a sudden short circuit, the windings are subjected to enormous axial and radial electromagnetic forces.
Pearl Electric employs rigorous pre-compression and constant-pressure drying processes during manufacturing, combined with high-density compression pads and integral end insulation, to ensure "zero displacement" of the windings when subjected to external short-circuit impacts.
For 230kV transformers, insulation performance is paramount. It must withstand high operating voltages, transient overvoltages, and lightning strikes. Under ultra-high voltage conditions, the electric field strength is extremely high, and any minor insulation defect can trigger partial discharge or even insulation breakdown.
Therefore, the structural design of the main insulation and longitudinal insulation is crucial:
Oil-Paper Insulation System: The 230kV transformer uses an internationally standard oil-paper insulation combination. High-quality transformer oil not only provides insulation but also serves as a heat transfer medium; while insulating paper, cardboard, and insulating tubing provide a robust solid insulation barrier.
Electrostatic Field Optimization and Shielding Design: In areas with concentrated electric fields, such as winding ends and lead connections, precise electrostatic shielding rings must be designed. By optimizing the radius of curvature of the metal surface, the electric field distribution is made more gradual, thereby strictly controlling the partial discharge within industry-leading standards (e.g., ≤ 10 ext{ pC).
Main Insulation and Longitudinal Insulation Construction:
Main Insulation: Employs a multi-layered interphase barrier and oil-gap mesh structure, meticulously calculating safe distances between windings, and between windings and the core and tank walls.
Longitudinal Insulation: Addressing voltage differences between turns and layers of the same winding, reinforced insulating paper is used for wrapping. After forming, high-vacuum drying and vacuum oil impregnation are performed to thoroughly remove air and trace moisture, ensuring the purity of the insulating medium.
As a core hub in the power grid transmission and distribution system, the reliability of 230kV oil-immersed power transformers directly determines the operational safety and power quality of the entire power network.
Basing its solutions on a three-pronged technical architecture of "low-loss core—high-stability winding—long-life insulation." This architecture integrates cutting-edge technologies such as high-permeability silicon steel materials, all-copper transposed conductors, oil-paper composite insulation, and intelligent oil monitoring. Coupled with rigorous verification through the full range of IEC 60076 type tests and factory tests, Pearl Electric has created a 230kV-class solution that combines high energy efficiency, high short-circuit withstand capability, and high insulation margin.
In the current context of the accelerated construction of new power systems, Pearl Electric is committed to providing time-tested transformer products for transmission upgrades, large-scale grid integration of new energy sources, and critical industrial loads, contributing to global energy transition and high-quality power grid development.
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