Off-Axis Lead Exit Arrangement for High Voltage Transformers
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Solution Overview
Problem
The existing lead exit arrangements for high voltage transformers or reactors require disassembly and reassembly during transportation, which exposes the hygroscopic insulation to the environment, increasing the risk of contamination and complicating the reassembly process due to the need for a turret and stress shield positioning.
Innovation Solution
A lead exit arrangement with a stress shield configured to receive winding leads off-axis with respect to the bushing axis, allowing for a compact design that eliminates the need for a turret and enables the stress shield to be mounted within the tank, thus simplifying transportation and assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a turret structure is used to support the bushing externally, then the bushing can be mounted outside the tank, but the turret must be disassembled during transportation which exposes the insulation to contamination risk
Solution Approach 1:
The stress shield is merged with the tank structure by being mounted inside the tank rather than externally. The stress shield serves dual functions: providing electrical stress management and housing the connection between winding leads and bushing. This integration eliminates the separate turret structure that would require disassembly, thereby preventing insulation exposure to environmental contamination during transportation.
Solution Approach 2:
The stress shield acts as an intermediary structure that provides both electrical field management and mechanical housing for the lead connection. By positioning the stress shield inside the tank and using it to house the connection, the design eliminates the need for an external turret while maintaining proper electrical stress distribution and connection integrity.
2Ease of manufacture
If the stress shield receives winding leads along the bushing axis, then the alignment is simplified, but the overall design becomes less compact and requires more space
Solution Approach 1:
The stress shield is designed to receive winding leads from directions other than along the bushing axis, utilizing off-axis orientations. This dimensional flexibility allows the leads to enter the stress shield from the side or at angles, enabling a more compact three-dimensional arrangement within the tank while maintaining proper electrical connections and stress management.
3Productivity
If the turret and bushing are detached for transportation, then transportation logistics are simplified, but the reassembly process becomes complex and time-consuming
Solution Approach 1:
The stress shield and tank are integrated as a single assembly with the stress shield mounted inside the tank. This merged structure eliminates the need for separate turret assembly and disassembly operations during transportation and installation, significantly simplifying the reassembly process while maintaining transportation flexibility.
Solution Approach 2:
The stress shield is pre-mounted within the tank during factory assembly, creating a integrated unit that requires no field assembly of the turret-bushing-stress shield subsystem. This preliminary integration eliminates complex reassembly operations at the installation site, reducing both time and potential for errors.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces the risk of contamination and simplifies the assembly process by maintaining the insulating integrity and eliminating the need for turret disassembly, while allowing for a more compact and efficient design that can accommodate multiple winding leads within the tank.
Implementation Method 1
Shielding and insulation, referred to as a stress shield, surrounds the connection between the bushing and the winding lead in the turret
Implementation Method 2
The turret is also typically filled with an insulating fluid, such as an oil, and the insulation is conditioned accordingly
Data Source
Figure 1
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Figure 4
AI summary
A lead exit arrangement (1) for a high voltage transformer/reactor (20) comprising an elongate bushing (2) having a bushing axis (B), a stress shield (5) located at a base (6) of the bushing (2) for receiving a winding lead (7) from a transformer (20) and housing a connection between the winding lead (7) and the base (6) of the bushing (2), the stress shield (5) configured to receive said winding lead (7) in a direction off-axis with respect to the bushing axis (B).