Low-Viscosity Fluid Bushing for Higher Current and Cooling
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Solution Overview
Problem
Existing bushings in electrical facilities face challenges with thermal performance and current carrying capacity, leading to potential damage and reduced operational safety and life expectancy.
Innovation Solution
A bushing design incorporating a low-viscosity insulating fluid, such as NYTRO® BIO 300X, and a condenser body with enhanced fluid circulation features, including holes and duct spacing paper, to improve thermal performance and cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional insulating fluid with higher viscosity is used in the bushing, then the bushing provides adequate electrical insulation, but the thermal performance is poor and current carrying capacity is limited
Solution Approach 1:
The patent changes the viscosity parameter of the insulating fluid by selecting specific fluids (synthetic ester oils, natural ester oils, or silicone oils) with viscosity between 2-10 cSt at 40°C and 1-3 cSt at 100°C. This parameter change enables improved convective cooling and heat dissipation while maintaining electrical insulation properties, thereby improving thermal performance without compromising operational safety
2Productivity
If the bushing operates at higher current, then the current carrying capacity increases, but the hotspot temperature increases leading to potential damage
Solution Approach 1:
The patent changes the thermal conductivity and viscosity parameters of the insulating fluid to optimize heat transfer. The selected fluids have thermal conductivity of 0.12-0.18 W/(m·K) and low viscosity, enabling efficient heat removal from the conductor. This allows the bushing to operate at higher currents while maintaining hotspot temperatures within safe limits, thereby increasing current capacity without excessive temperature rise
3Reliability
If mineral oil is used as insulating fluid, then the bushing provides good electrical insulation, but the fluid has high viscosity leading to poor circulation and cooling
Solution Approach 1:
The patent changes the viscosity parameter from conventional mineral oil (typically 15-20 cSt at 40°C) to low-viscosity synthetic esters, natural esters, or silicone oils (2-10 cSt at 40°C, 1-3 cSt at 100°C). This parameter change significantly improves fluid circulation speed and convective cooling efficiency while the chemical composition changes maintain or enhance electrical insulation properties
Solution Approach 2:
The patent employs composite material strategies by selecting insulating fluids that combine multiple desirable properties: low viscosity for circulation, adequate thermal conductivity for heat transfer, and high dielectric strength for electrical insulation. The specific fluid compositions (synthetic esters, natural esters, silicone oils) represent optimized composite molecular structures that balance these competing requirements
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
Enhances thermal performance, increases current capacity, reduces hotspot temperatures, and extends operational safety and life expectancy while being environmentally friendly.
Implementation Method 1
the low viscosity of the insulating fluid enables an improved circulation of the insulating fluid in the bushing. Thereby, the thermal performance of the bushing can be enhanced and cooling by convection can be improved
Implementation Method 2
The first and second holes enable circulation of the insulating fluid between the inside and the outside of the electrical conductor. Thereby, a cooling of the hotspot of the electrical conductor is improved
Data Source
AI summary
A bushing includes an insulating housing, an electrical conductor, extending through the housing and an insulating fluid in the housing, wherein the insulating fluid has a viscosity at a temperature of 100° C. of equal or less than 2 mm2/s. The bushing includes a condenser body surrounding the electrical conductor, wherein the condenser body includes electrically insulating layers and electrically conductive layers, wherein the electrically insulating layers are formed from a paper impregnated with the insulating fluid.