Capacitor Oil Crystallization Prevention at -50°C
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Solution Overview
Problem
Capacitor oils face challenges in maintaining high breakdown voltage across a wide temperature range of -50°C to 30°C while preventing crystallization and addressing toxicity concerns, as existing solutions like dibenzyltoluene increase viscosity and have high biological accumulation properties.
Innovation Solution
A mixture of 1,1-diphenylethane and benzyltoluene with a specific mass ratio, combined with an epoxy compound to reduce chlorine content, is used to create a capacitor oil with a kinematic viscosity of 3.00 mm²/s or lower, ensuring the oil remains fluid at -50°C and maintains high breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If dibenzyltoluene is added to lower the melting point, then the crystallization temperature decreases, but the viscosity increases and mobility decreases
Solution Approach 1:
The patent changes the chemical composition parameters by using 1,1-diphenylethane instead of dibenzyltoluene, and controls the isomer ratio of benzyltoluene (ortho-isomer ≤ 10%, para-isomer ≤ 10%, meta-isomer ≥ 80%) to achieve the desired balance between low crystallization temperature and low viscosity
Solution Approach 2:
The patent creates a composite mixture of 1,1-diphenylethane and benzyltoluene with specific composition ratios (1,1-diphenylethane: 20-40 mass%, benzyltoluene: 60-80 mass%) to combine the advantages of low melting point and low viscosity while avoiding the disadvantages of individual components
2Reliability
If dibenzyltoluene is added to prevent crystallization, then the oil remains fluid at low temperatures, but the biological accumulation properties worsen
Solution Approach 1:
The patent extracts dibenzyltoluene from the composition and replaces it with 1,1-diphenylethane and controlled benzyltoluene isomers, eliminating the harmful substance while maintaining the desired low-temperature fluidity performance
Solution Approach 2:
The patent substitutes the environmentally problematic dibenzyltoluene with more environmentally friendly alternatives (1,1-diphenylethane and controlled benzyltoluene isomers) that have lower biological accumulation properties while achieving the same functional effect
3Reliability
If benzyltoluene is used to achieve high breakdown voltage, then the insulation properties improve, but the melting point increases
Solution Approach 1:
The patent changes the melting point parameter by controlling the isomer composition of benzyltoluene (using predominantly meta-isomer with ≥80%) and adding 1,1-diphenylethane, while maintaining the high breakdown voltage property inherent to benzyltoluene
Solution Approach 2:
The patent creates a composite system combining 1,1-diphenylethane and benzyltoluene with controlled isomer ratios, where the mixture exhibits lower melting point than pure benzyltoluene while maintaining high breakdown voltage characteristics
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
The resulting capacitor oil effectively prevents crystallization at -50°C and maintains excellent insulation properties up to 30°C, with components that are non-toxic and suitable for practical use, enhancing the operational range and safety of oil-impregnated capacitors.
Implementation Method 1
even though the freezing point depression could be expected by addition of dibenzyltoluene, it is not decreased as much as the mass of the addition of dibenzyltoluene due to the high molecular weight thereof
Implementation Method 2
low viscosity and low melting point
Implementation Method 3
high hydrogen gas absorbability
Implementation Method 4
high breakdown voltage
Data Source
AI summary
The present invention provides a capacitor oil that can maintain breakdown voltage at a high level in a wide temperature range of -50°C to 30°C, extremely unlikely precipitates as crystals in particular at -50°C and thus has excellent properties both at normal temperature and a lower temperature. The capacitor oil of the present invention comprises 1,1-diphenylethane and benzyltoluene, wherein the mass ratio of 1, 1-diphenylethane to benzyltoluene is 0.8 to 2.0, the total amount of the ortho-isomer and para-isomer in the benzyltoluene is 90 percent by mass or less, and the composition has a 40°C kinematic viscosity of 3.00 mm2/s or lower.